Academic literature on the topic 'Exercise flow rates'
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Journal articles on the topic "Exercise flow rates"
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Villar, Rodrigo, and Richard L. Hughson. "Effect of altered arterial perfusion pressure on vascular conductance and muscle blood flow dynamic response during exercise in humans." Journal of Applied Physiology 114, no. 5 (2013): 620–27. http://dx.doi.org/10.1152/japplphysiol.01094.2012.
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Changes in vascular conductance (VC) are required to counter changes in muscle perfusion pressure (MPP) to maintain muscle blood flow (MBF) during exercise. We investigated the recruitment of VC as a function of peak VC measured in three body positions at two different work rates to test the hypothesis that adaptations in VC compensated changes in MPP at low-power output (LPO), but not at high-power output (HPO). Eleven healthy volunteers exercised at LPO and HPO (repeated plantar flexion contractions at 20–30% maximal voluntary contraction, respectively) in horizontal (HOR), 35° head-down tilt (HDT), and 45° head-up tilt (HUT). Muscle blood flow velocity and popliteal diameter were measured by ultrasound to determine MBF, and VC was estimated by dividing MBF flow by MPP. Peak VC was unaffected by body position. The rates of increase in MBF and VC were significantly faster in HUT and slower in HDT than HOR, and rates were faster in LPO than HPO. During LPO exercise, the increase in, and steady-state values of, MBF were less for HUT and HDT than HOR; the increase in VC was less in HUT than HOR and HDT. During HPO exercise, MBF in the HDT was reduced compared with HOR and HUT, even though VC reached 92% VC peak, which was greater than HOR, which was, in turn, greater than HUT. Reduced MBF during HPO HDT exercise had the functional consequence of a significant increase in muscle electromyographic index, revealing the effects of MPP on O2 delivery during exercise.
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McDonald, R. B., J. S. Hamilton, J. S. Stern, and B. A. Horwitz. "Regional blood flow of exercise-trained younger and older cold-exposed rats." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 256, no. 5 (1989): R1069—R1075. http://dx.doi.org/10.1152/ajpregu.1989.256.5.r1069.
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O2 consumption (thermogenesis) and regional blood flows (measured using radioactively labeled microspheres) were evaluated in younger (12 mo) and older (24 mo) sedentary and exercised male Fischer 344 (F-344) rats. These variables were measured at rest and during exposure to 6 degrees C. Exercise-trained rats were run on a motor-driven treadmill 5 days/wk, 1 h/day, at 20 m/min for 6 mo. Resting rates of O2 consumption did not differ with age or exercise training. However, thermogenesis during cold exposure was significantly greater in the older exercised rats than in the other three groups. This difference did not reflect a greater contribution from brown fat as indicated by the fact that total blood flow to the brown fat depots during cold exposure was not greater in the older exercised vs. the other rat groups. Neither exercise training nor age had a significant effect on specific resting blood flow (expressed as ml.min-1.g tissue mass-1) to most of the organs measured, including heart, kidney, brown fat, white fat, and skeletal muscle. The notable exception to this was in the spleen of the older sedentary animals where flow was diminished compared with that in the older exercised animals. We conclude that aging, between 12 and 24 mo of age, and/or exercise training have only a minor effect on regional blood flow of F-344 rats during rest or cold exposure and that the enhanced thermogenesis seen in cold-exposed older exercised vs. sedentary F-344 rats cannot be explained by a greater contribution from brown fat.
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Marciniuk, D. D., G. Sridhar, R. E. Clemens, T. A. Zintel, and C. G. Gallagher. "Lung volumes and expiratory flow limitation during exercise in interstitial lung disease." Journal of Applied Physiology 77, no. 2 (1994): 963–73. http://dx.doi.org/10.1152/jappl.1994.77.2.963.
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Lung volumes were measured at rest and during exercise by an open-circuit N2-washout technique in patients with interstitial lung disease (ILD). Exercise tidal flow-volume (F-V) curves were also compared with maximal F-V curves to investigate whether these patients demonstrated flow limitation. Seven patients underwent 4 min of constant work rate bicycle ergometer exercise at 40, 70, and 90% of their previously determined maximal work rates. End-expiratory lung volume and total lung capacity were measured at rest and near the end of each period of exercise. There was no significant change in end-expiratory lung volume or total lung capacity when resting measurements were compared with measurements at 40, 70, and 90% work rates. During exercise, expiratory flow limitation was evident in four patients who reported stopping exercise because of dyspnea. In the remaining patients who discontinued exercise because of leg fatigue, no flow limitation was evident. In all patients, the mean ratio of maximal minute ventilation to maximal ventilatory capacity (calculated from maximal F-V curves) was 67%. We conclude that lung volumes during exercise do not significantly differ from those at rest in this population and that patients with ILD may demonstrate expiratory flow limitation during exercise. Furthermore, because most patients with ILD are not breathing near their maximal ventilatory capacity at the end of exercise, we suggest that respiratory mechanics are not the primary cause of their exercise limitation.
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Powers, S. K., R. E. Beadle, D. Thompson, and J. Lawler. "Ventilatory and blood gas dynamics at onset and offset of exercise in the pony." Journal of Applied Physiology 62, no. 1 (1987): 141–48. http://dx.doi.org/10.1152/jappl.1987.62.1.141.
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The purpose of these experiments was to examine the temporal pattern of arterial carbon dioxide tension (PaCO2) to assess the relationship between alveolar ventilation (VA) and CO2 return to the lung at the onset and offset of submaximal treadmill exercise. Five healthy ponies exercised for 8 min at two work rates: 50 m/min 6% grade and 70 m/min 12% grade. PaCO2 decreased (P less than 0.05) below resting values within 1 min after commencement of exercise at both work rates and reached a nadir at 90 s. PaCO2 decreased maximally by 2.5 and 3.5 Torr at the low and moderate rate, respectively. After the nadir, PaCO2 increased across time during both work rates and reached values that were not significantly different (P greater than 0.05) from rest at minute 4 of exercise. Partial pressure of O2 in arterial blood and arterial pH reflected hyperventilation during the first 3 min of exercise. At the termination of exercise PaCO2 increased (1.5 Torr) above rest (P less than 0.05), reaching a zenith at 2–3 min of recovery. These data suggest that VA and CO2 flow to the lung are not tightly matched at the onset and offset of exercise in the pony and thus challenges the traditional concept of blood gas homeostasis during muscular exercise.
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McClaran, Steven R., Craig A. Harms, David F. Pegelow, and Jerome A. Dempsey. "Smaller lungs in women affect exercise hyperpnea." Journal of Applied Physiology 84, no. 6 (1998): 1872–81. http://dx.doi.org/10.1152/jappl.1998.84.6.1872.
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We subjected 29 healthy young women (age: 27 ± 1 yr) with a wide range of fitness levels [maximal oxygen uptake (V˙o 2 max): 57 ± 6 ml ⋅ kg−1 ⋅ min−1; 35–70 ml ⋅ kg−1 ⋅ min−1] to a progressive treadmill running test. Our subjects had significantly smaller lung volumes and lower maximal expiratory flow rates, irrespective of fitness level, compared with predicted values for age- and height-matched men. The higher maximal workload in highly fit (V˙o 2 max > 57 ml ⋅ kg−1 ⋅ min−1, n = 14) vs. less-fit (V˙o 2 max < 56 ml ⋅ kg−1 ⋅ min−1, n = 15) women caused a higher maximal ventilation (V˙e) with increased tidal volume (Vt) and breathing frequency (fb) at comparable maximal Vt/vital capacity (VC). More expiratory flow limitation (EFL; 22 ± 4% of Vt) was also observed during heavy exercise in highly fit vs. less-fit women, causing higher end-expiratory and end-inspiratory lung volumes and greater usage of their maximum available ventilatory reserves. HeO2 (79% He-21% O2) vs. room air exercise trials were compared (with screens added to equalize external apparatus resistance). HeO2 increased maximal expiratory flow rates (20–38%) throughout the range of VC, which significantly reduced EFL during heavy exercise. When EFL was reduced with HeO2, Vt, fb, andV˙e (+16 ± 2 l/min) were significantly increased during maximal exercise. However, in the absence of EFL (during room air exercise), HeO2 had no effect onV˙e. We conclude that smaller lung volumes and maximal flow rates for women in general, and especially highly fit women, caused increased prevalence of EFL during heavy exercise, a relative hyperinflation, an increased reliance on fb, and a greater encroachment on the ventilatory “reserve.” Consequently, Vt andV˙e are mechanically constrained during maximal exercise in many fit women because the demand for high expiratory flow rates encroaches on the airways’ maximum flow-volume envelope.
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Walsh, Michael L., Chiyo Takeda, Aya Takahashi, et al. "Volitional hyperventilation during ramp exercise to exhaustion." Applied Physiology, Nutrition, and Metabolism 31, no. 3 (2006): 211–17. http://dx.doi.org/10.1139/h05-025.
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The purpose of this study was to determine whether volitional hyperventilation at 20 L·min-1 above normal exercise values affected exercise duration while performing ramp exercise to exhaustion. Nine healthy subjects performed a ramp exercise test to exhaustion. On a subsequent test they hyperventilated, with the aid of visual and audio feedback, at 20 L·min-1 greater than their initial test. Ramp exercise time to exhaustion was substantially reduced from 771.6 ± 85.2 s to 726.6 ± 86.6 s (p < 0.002) with the additional hyperventilation. Subjects underwent 2 more ramp exercise tests and performed a 5 s maximum voluntary ventilation or a forced vital capacity test at work rates corresponding to rest, below lactate threshold (LT), above LT, immediately after exercise, and 3 min recovery. Generally, the flow rates were not affected by exercise below LT and were enhanced during above-LT exercise, exhaustion, and recovery. This indicated a change in pulmonary function that is dependent on exercise intensity. In spite of this increased ability to generate high flow rates, exercise performance was diminished when respiratory muscle work was increased volitionally by 20 L·min-1, indicating a strong coupling between respiratory muscle work and fatigue during ramp exercise in normal subjects.Key words: ventilation, fatigue, pulmonary function, MVV, FVC.
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Fatela, Pedro, Goncalo V. Mendonca, António Prieto Veloso, Janne Avela, and Pedro Mil-Homens. "Blood Flow Restriction Alters Motor Unit Behavior During Resistance Exercise." International Journal of Sports Medicine 40, no. 09 (2019): 555–62. http://dx.doi.org/10.1055/a-0888-8816.
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AbstractWe aimed to determine whether blood flow restriction (BFR) alters the characteristics of individual motor units during low-intensity (LI) exercise. Eight men (26.0±3.8 yrs) performed 5 sets of 15 knee extensions at 20% of one-repetition maximum (with and without BFR). Maximal isometric voluntary contractions (MVC) were performed before and after exercise to quantify force decrement. Submaximal isometric voluntary contractions were additionally performed for 18 s, matching trapezoidal target-force trajectories at 40% pre-MVC. EMG activity was recorded from the vastus lateralis muscle. Then, signals were decomposed to extract motor unit recruitment threshold, firing rates and action potential amplitudes (MUAP). Force decrement was only seen after LI BFR exercise (–20.5%; p<0.05). LI BFR exercise also induced greater decrements in the linear slope coefficient of the regression lines between motor unit recruitment threshold and firing rate (BFR: –165.1±120.4 vs. non-BFR: –44.4±33.1%, p<0.05). Finally, there was a notable shift towards higher values of firing rate and MUAP amplitude post-LI BFR exercise. Taken together, our data indicate that LI BFR exercise increases the activity of motor units with higher MUAP amplitude. They also indicate that motor units with similar MUAP amplitudes become activated at higher firing rates post-LI BFR exercise.
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Şahin, Elif, Teslime Ayaz, and Melda Saglam. "Acute effects of blood flow restricted aerobic exercise in type 2 diabetes mellitus." Medicine 103, no. 31 (2024): e39031. http://dx.doi.org/10.1097/md.0000000000039031.
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Background: This study aimed to compare the acute effects of aerobic exercise performed with blood flow restriction (BFR), a novel method to increase exercise gains, with blood free flow (BFF) conditions in type 2 diabetes mellitus (T2DM). Methods: Fifteen individuals with T2DM performed BFF and BFR (40% of arterial occlusion pressure) cycling exercises 48 hours apart, at equal intensity (45% heart rate reserve) and duration (38 minutes). Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), blood glucose, heart rate, and muscle oxygen saturation (SmO2) were assessed before-after and during exercise sessions. Results: SBP, DBP, and MAP in the overload phase were higher in the BFR group than in the BFF group (P = .009, 0.031, and 0.013, respectively). Changes in blood pressure (∆SBP and ∆DBP) were similar between the BFF and BFR groups (P > .05), whereas ∆MAP differed (P = .016). Changes in blood glucose levels and heart rates were not significantly different between the groups. Although SmO2baseline was lower in the BFR group (P = .049), SmO2min and SmO2max did not differ significantly between the BFF and BFR groups. Conclusion: The similar decrease in blood glucose levels between the groups suggests that BFR exercise is favorable in terms of hypoglycemia. The higher blood pressure observed during the BFR exercise remained within safe limits. These results suggest that people with T2DM can safely perform BFR aerobic exercises; however, further studies are required.
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Lutjemeier, Barbara J., Akira Miura, Barry W. Scheuermann, Shunsaku Koga, Dana K. Townsend, and Thomas J. Barstow. "Muscle contraction-blood flow interactions during upright knee extension exercise in humans." Journal of Applied Physiology 98, no. 4 (2005): 1575–83. http://dx.doi.org/10.1152/japplphysiol.00219.2004.
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To test for evidence of a muscle pump effect during steady-state upright submaximal knee extension exercise, seven male subjects performed seven discontinuous, incremental exercise stages (3 min/stage) at 40 contractions/min, at work rates ranging to 60–75% peak aerobic work rate. Cardiac cycle-averaged muscle blood flow (MBF) responses and contraction-averaged blood flow responses were calculated from continuous Doppler sonography of the femoral artery. Net contribution of the muscle pump was estimated by the difference between mean exercise blood flow (MBFM) and early recovery blood flow (MBFR). MBFM rose in proportion with increases in power output with no significant difference between the two methods of calculating MBF. For stages 1 and 5, MBFM was greater than MBFR; for all others, MBFM was similar to MBFR. For the lighter work rates ( stages 1–4), there was no significant difference between exercise and early recovery mean arterial pressure (MAP). During stages 5–7, MAP was significantly higher during exercise and fell significantly early in recovery. From these results we conclude that 1) at the lightest work rate, the muscle pump had a net positive effect on MBFM, 2) during steady-state moderate exercise ( stages 2–4) the net effect of rhythmic muscle contraction was neutral (i.e., the impedance due to muscle contraction was exactly offset by the potential enhancement during relaxation), and 3) at the three higher work rates tested ( stages 5–7), any enhancement to flow during relaxation was insufficient to fully compensate for the contraction-induced impedance to muscle perfusion. This necessitated a higher MAP to achieve the MBFM.
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Bayly, W. M., D. A. Schultz, D. R. Hodgson, and P. D. Gollnick. "Ventilatory responses of the horse to exercise: effect of gas collection systems." Journal of Applied Physiology 63, no. 3 (1987): 1210–17. http://dx.doi.org/10.1152/jappl.1987.63.3.1210.
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Experiments were undertaken to determine whether respiratory masks worn by horses exercising strenuously on a treadmill may interfere with normal gas exchange. Four collection systems, two flow-through systems and two incorporating one-way valve systems with subject-generated airflow were studied. Six horses performed standard treadmill exercise tests consisting of a 2-min warm up followed by galloping 1 min each at 8,9, and 10 m/s. Each horse exercised six times while wearing each of the four respiratory masks. Each flow-through system was used twice with flow rates of 2,360 and 3,840 l/min for one system, and 3,840 and 6,300 l/min for the other. Arterial blood gas tensions were measured during exercise at each speed for each system and were compared with values measured when the horses performed the same test without wearing a mask. Hypercapnia developed during exercise with each of the respiratory masks except with the 6,300–l/min flow-through system. All horses became hypoxemic during every exercise test, but it was most severe when systems incorporating one-way valves were used. This, plus the degree of hypercapnia observed and a suboptimal heart rate-O2 uptake relationship, indicated that such systems severely impede ventilation and suggest that experiments performed while utilizing them do not represent the normal exercise condition.
Dissertations / Theses on the topic "Exercise flow rates"
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Prisby, Rhonda D., Michael W. Ramsey, Bradley J. Behnke, et al. "Aging Reduces Skeletal Blood Flow, Endothelium-Dependent Vasodilation and Nitric Oxide Bioavailability in Rats." Digital Commons @ East Tennessee State University, 2009. https://dc.etsu.edu/etsu-works/4142.
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Introduction: Aging has been shown to diminish bone blood flow in rats and humans. The purpose of this study was to determine whether blood flow to regions of the femur perfused primarily through the principal nutrient artery (PNA) are diminished with aging and whether this putative reduction in flow is associated with impaired endothelium‐dependent vasodilation.
Materials and Methods: Blood flow was measured in conscious young adult (4–6 mo old) and aged (24–26 mo old) male Fischer‐344 rats using radiolabeled microspheres. Endothelium‐dependent vasodilation of the PNA was assessed in vitro using acetylcholine (ACh), whereas the contribution of the NO synthase (NOS) and cyclooxygenase (COX) signaling pathways to endothelium‐dependent vasodilation was determined using the NOS and COX inhibitors L‐NAME and indomethacin, respectively.
Results: Femoral blood flow in the aged rats was 21% and 28% lower in the proximal and distal metaphyses, respectively, and 45% lower in the diaphyseal marrow. Endothelium‐dependent vasodilation was reduced with old age (young: 83 ± 6% maximal relaxation; aged: 62 ± 5% maximal relaxation), whereas endothelium‐independent vasodilation (sodium nitroprusside) was unaffected by age. The reduction in endothelium‐dependent vasodilation was mediated through impairment of the NOS signaling pathway, which resulted in lower NO bioavailability (young: 168 ± 56 nM; aged: 50 ± 7 nM).
Conclusions: These data show that reductions in metaphyseal bone and diaphyseal marrow perfusion with old age are associated with diminished endothelium‐dependent vasodilation through an impairment of the NOS mechanism. Such age‐related changes in bone perfusion and vascular NO signaling could impact clinical bone loss, increase risk of fracture, and impair fracture healing in the elderly.
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Allgrove, Judith E. "Factors influencing the mucosal immune response to exercise." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/12325.
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Despite the abundance of research conducted into the effects of exercise on mucosal immunity the results remain controversial. Much of the inconsistencies arise from the exercise protocols, the participants studied and their nutritional status, as well as methodological and analytical differences. The purpose of this thesis was to examine the influence of some of these factors, and to investigate potential means of enhancing the mucosal immune response to exercise. In study 1 (Chapter 3) it was shown that a fed or fasted state 2 h prior to exercise had no effect on the s-IgA concentration or secretion rate during prolonged exercise. However, when participants were fed during exercise (Chapter 4), the secretion rate of salivary antimicrobial proteins lysozyme and a-amylase increased, but sIgA remained unchanged. These changes were likely due to the activation of mechanical and gustatory receptors leading to a reflex stimulation of protein secretion via the autonomic nerves, rather than changes in stress hOnliones, since cortisol did not change significantly during exercise. Study 3 (Chapter 5) extended these findings where it was demonstrated that chewing flavoured gum during exercise enhanced lysozyme and a-amylase secretion but resulted in a small reduction in s-IgA secretion rate. Salivary antimicrobial proteins are affected by the exercise intensity since both s-IgA and lysozyme secretion rate increased post -exercise following an incremental test to exhaustion, but not after exercise at 50% Y02max. Moreover, lysozyme secretion rate was also elevated following exercise at 75% Y02mru<, whereas s-IgA remained unchanged. These effects are thought to be mediated by increased sympathetic nervous system activity reflected by the concomitant increases in (lamylase and chromogranin A, rather than the hypothalamic-pituitary-adrenal axis. Resting mucosal immunity exhibits significant gender differences. In study 1 (Chapter 3) s-IgA concentration, secretion rate and osmolality were found to be lower in females than in males at rest. In addition, saliva flow rate was found to be lower in females compared with males in study 5 (Chapter 7). However, these differences did not appear to influence the salivary responses to acute exercise or exercise training. Chronic exercise training in elite male and female swimmers resulted in lower levels of s-IgA secretion rate following periods of intense training prior to competition compared with post-competition (Chapter 7), but these levels were not directly associated with reported episodes of respiratory illness.
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Prisby, Rhonda D., Michael W. Ramsey, Bradley J. Behnke, et al. "Aging Reduces Skeletal Blood Flow, Endothelium-Dependent Vasodilation and Nitric Oxide Bioavailability in Rats." Digital Commons @ East Tennessee State University, 2007. https://dc.etsu.edu/etsu-works/4130.
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We determined whether aging diminishes bone blood flow and impairs endothelium‐dependent vasodilation. Femoral perfusion was lower in old animals, as well as endothelium‐dependent vasodilation and NO bioavailability. These effects could contribute to old age—related bone loss and the increased risk of fracture.
Introduction: Aging has been shown to diminish bone blood flow in rats and humans. The purpose of this study was to determine whether blood flow to regions of the femur perfused primarily through the principal nutrient artery (PNA) are diminished with aging and whether this putative reduction in flow is associated with impaired endothelium‐dependent vasodilation.
Materials and Methods: Blood flow was measured in conscious young adult (4–6 mo old) and aged (24–26 mo old) male Fischer‐344 rats using radiolabeled microspheres. Endothelium‐dependent vasodilation of the PNA was assessed in vitro using acetylcholine (ACh), whereas the contribution of the NO synthase (NOS) and cyclooxygenase (COX) signaling pathways to endothelium‐dependent vasodilation was determined using the NOS and COX inhibitors L‐NAME and indomethacin, respectively.
Results: Femoral blood flow in the aged rats was 21% and 28% lower in the proximal and distal metaphyses, respectively, and 45% lower in the diaphyseal marrow. Endothelium‐dependent vasodilation was reduced with old age (young: 83 ± 6% maximal relaxation; aged: 62 ± 5% maximal relaxation), whereas endothelium‐independent vasodilation (sodium nitroprusside) was unaffected by age. The reduction in endothelium‐dependent vasodilation was mediated through impairment of the NOS signaling pathway, which resulted in lower NO bioavailability (young: 168 ± 56 nM; aged: 50 ± 7 nM).
Conclusions: These data show that reductions in metaphyseal bone and diaphyseal marrow perfusion with old age are associated with diminished endothelium‐dependent vasodilation through an impairment of the NOS mechanism. Such age‐related changes in bone perfusion and vascular NO signaling could impact clinical bone loss, increase risk of fracture, and impair fracture healing in the elderly.
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Holdsworth, Clark T. "Effects of dietary fish oil on skeletal muscle vascular control in chronic heart failure rats: rest and exercise." Thesis, Kansas State University, 2013. http://hdl.handle.net/2097/15814.
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Master of Science<br>Department of Kinesiology<br>Timothy I. Musch<br>Impaired vasomotor control in chronic heart failure (CHF) limits the delivery of O[subscript]2 to skeletal muscle during exercise. Previous results demonstrate significant increases in skeletal muscle blood flow (BF) during exercise with omega-3 polyunsaturated fatty acid (PUFA) supplementation via fish oil (FO) versus safflower oil (SO) in healthy rats (Stebbins CL et al., Int J Sport Nutr Exerc Metab 20:475-86, 2010). Whether PUFA supplementation with FO will improve vasomotor control in CHF and skeletal muscle BF during exercise remains to be determined. This investigation tested the hypothesis that PUFA supplementation with FO would augment the skeletal muscle BF response to exercise in rats with CHF when compared to SO. CHF was induced in male Sprague-Dawley rats by myocardial infarction produced via left coronary artery ligation. Rats were then randomized to dietary FO (20% docosahexaenoic acid and 30% eicosapentaenoic acid, n = 8) or SO (5% safflower, n = 6) supplementation for 6 weeks. Rats remained on their respective diets until final experiments were conducted. Following acute instrumentation and recovery (> 1 hour), mean arterial pressure (MAP), skeletal muscle BF to the total hindlimb and individual muscles (via radiolabeled microspheres), and blood lactate concentration were determined during rest, submaximal treadmill exercise and exercise+LNAME (20 m · min[superscript]-[superscript]1, 5% incline). Left ventricular end-diastolic pressure (LVEDP) measured in the SO and FO groups during instrumentation were similar and demonstrated moderate CHF (LVEDP; SO: 14 ± 2; FO: 11 ± 1 mmHg, P>0.05). During submaximal exercise, MAP (SO: 128 ± 3; FO: 132 ± 3 mmHg) and blood lactate (SO: 3.8 ± 0.4; FO: 4.6 ± 0.5 mmol · l[superscript]-[superscript]1) were similar (P>0.05) between groups. Exercising hindlimb skeletal muscle BF was higher in SO compared to FO (SO: 120 ± 11; FO: 93 ± 4 ml · min[superscript]-[superscript]1 · 100 g[superscript]-[superscript]1). Specifically, 17 of 28 individual hindlimb muscle BF’s were higher (P<0.05) in SO. These data suggest that PUFA supplementation with FO in rats with moderate CHF decreases the skeletal muscle BF response to submaximal whole body exercise.
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Schwagerl, Peter J. "The effects of ascorbic acid on skeletal muscle blood flow in aged rats." Thesis, Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/4141.
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Hunt, Lindsey. "Examining the effects of caffeine ingestion on human thermoregulation during exercise in the heat in habituated and non-habituated individuals." Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/23167.
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Purpose: In most thermoregulatory research, participants are asked to abstain from consuming caffeine prior to experimental trials due to an assumed confounding effect on core temperature, skin blood flow and/or sweating responses. Yet, evidence supporting this notion appears inconclusive. We aimed to rigorously assess the impact of acute caffeine ingestion on thermoregulatory responses to steady-state exercise in the moderate heat in both caffeine-habituated and non-habituated individuals. Methods: A total of 28 participants (Habituated (HAB), n=14, 4 women; Non-Habituated (NHAB), n=14, 6 women) cycled at a fixed metabolic heat production on two separate occasions: 60 minutes after ingesting i) 5 mg·kg-1 caffeine (CAF) or ii) 5 mg·kg-1 maltodextrin placebo (PLA), in a double-blinded randomised and counter-balanced order. Environmental conditions were 30.6±0.9°C, 31±1 % RH. Results: The rise in esophageal temperature from baseline (ΔTes) with CAF was greater in the HAB group (P<0.001), but not the NHAB group (P=0.34) (CAFHAB interaction: P=0.001). Skin blood flow responses on the arm and the back were attenuated with CAF in the HAB group (CAFHAB interaction: P<0.05) but not in the NHAB group (CAFHAB interaction: Arm: P>0.05). WBSL was not between CAF and PLA (P=0.18). Conclusion: A greater ΔTes with CAF was observed in the HAB group but not the NHAB group, possibly due to an attenuated skin blood flow on the forearm and back with CAF compared to PLA in the HAB group only. These findings support the practice of requesting habituated caffeine-users to abstain from all sources of caffeine prior to participating in thermoregulatory research studies. However, the restriction of caffeine intake for non-habituated individuals (from incidental sources, e.g. chocolate, tea etc) seems unnecessary.
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Glean, Angela A. "Effects of nitrite infusion on skeletal muscle vascular control during exercise in rats with chronic heart failure." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/19770.
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Master of Science<br>Department of Kinesiology<br>Timothy I. Musch<br>Chronic heart failure (CHF) reduces nitric oxide (NO) bioavailability and impairs skeletal muscle vascular control during exercise. Reduction of nitrite (NO[subscript]2-) to NO may impact exercise-induced hyperemia particularly in muscles with pathologically-reduced O[subscript]2 delivery. We tested the hypothesis that NO[subscript]2- infusion would increase exercising skeletal muscle blood flow (BF) and vascular conductance (VC) in CHF rats with a preferential effect in muscles composed primarily of type IIb+IId/x fibers. CHF (coronary artery ligation) was induced in adult male, Sprague-Dawley rats. Following a >21 day recovery, mean arterial pressure (MAP, carotid artery catheter) and skeletal muscle BF (radiolabelled microspheres) were measured during treadmill exercise (20 m•min[superscript]-1, 5% incline) with and without NO[subscript]2- infusion. The myocardial infarct size (35 ± 3%) indicated moderate CHF. NO[subscript]2- infusion increased total hindlimb skeletal muscle VC (CHF: 0.85 ± 0.09, CHF+NO[subscript]2-: 0.93 ± 0.09 ml•min[superscript]-1•100g[superscript]-1•mmHg[superscript]-1, p<0.05) without changing MAP (CHF: 123 ± 4 mmHg, CHF+NO[subscript]2-: 120 ± 4 mmHg, p=0.17). Total hindlimb skeletal muscle BF was not significantly different (CHF: 102 ± 7, CHF+NO[subscript]2-: 109 ± 7 ml•min[superscript]-1•100g[superscript]-1, p>0.05). BF increased in 6 (~21%) and VC in 8 (~29%) of the 28 individual muscles and muscle parts. Muscles and muscle portions exhibiting greater BF and VC following NO[subscript]2- infusion were comprised of ≥63% type IIb+IId/x muscle fibers. These data demonstrate that NO[subscript]2- infusion can augment skeletal muscle vascular control during exercise in CHF rats. Given the targeted effects shown herein, a NO[subscript]2[superscript]--based therapy may provide an attractive “needs-based” approach for treatment of the vascular dysfunction in CHF.
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Bond, Bert. "The influence of exercise intensity on vascular health outcomes in adolescents." Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/18057.
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Cardiovascular diseases (CVD) are the leading cause of death, and the underlying atherosclerotic process has its origin in youth. Physical activity lowers future CVD risk, however few adolescents achieve the recommended minimum amount of daily activity and interventions fail to meaningfully increase activity levels in this group. It is therefore essential to identify how small volumes of exercise can be optimised for the primary prevention of CVD. The purpose of this thesis is to identify the influence of exercise intensity on vascular health outcomes in adolescents, and to assess the efficacy of 2 weeks of low volume, high-intensity interval training on CVD risk factors in this population. Chapter 4 demonstrates that a single bout of high-intensity interval exercise (HIIE) performed one hour before a high fat meal elicits comparable reductions in postprandial lipaemia as a work-matched bout of moderate-intensity exercise (MIE) in girls. However, neither exercise attenuated postprandial lipaemia in the boys. Additionally, HIIE elicited a superior increase in postprandial fat oxidation and decrease in blood pressure, and this was sex independent. These findings are furthered in Chapter 5, which identified that accumulating HIIE, but not MIE, favourably modulates glycaemic control, postprandial blood pressure and fat oxidation in adolescents irrespective of sex. A high fat meal was included in Chapter 6 in order to impair vascular function via oxidative stress. Postprandial vascular function was preserved following MIE, but improved after HIIE, and these changes were not related to changes in postprandial lipaemia or total antioxidant status. Chapter 7 addressed the time course of the changes in vascular function post exercise, and identified that HIIE promotes superior changes in vascular function than MIE. Finally, Chapter 8 identified that 2 weeks of high-intensity interval training improved novel (endothelial function and heart rate variability), but not traditional CVD factors in adolescent boys and girls. However, most of these favourable changes were lost 3 days after training cessation. Thus, this thesis demonstrates that vascular health outcomes are positively associated with exercise intensity. Given that HIIE was perceived to be more enjoyable than MIE in Chapters 4, 6 and 7, performing HIIE appears to be an effectual and feasible alternative to MIE for the primary prevention of CVD.
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Parr, Sharon M. "The effects of graduated exercise at the piano on the pianist's cardiac output, forearm blood flow, heart rate, and blood pressure." Virtual Press, 1985. http://liblink.bsu.edu/uhtbin/catkey/434086.
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The purpose of this study was to determine the effects of graduated exercise at the piano on the pianist's cardiac output, forearm blood flow, heart rate, and blood pressure. Also considered were the effects of piano practice conditioning, general cardiovascular conditioning, and acute cigarette smoking on the aforementioned parameters during and after graduated piano exercise.Fifteen adult pianists participated in the study. The piano exercises consisted of bilateral scales played in eight three-minute stages. Tempo was constant within stages but increased with each new stage. Cardiac output and forearm blood flow were monitored by electrical impedance utilizing a tetrapolar electrode-placement system.FindingsCardiac output, forearm blood flow, heart rate, and systolic blood pressure generally increased proportionally to exercise intensity and returned to basal levels within a five-minute recovery period.ConclusionsStrenuous piano exercise stresses the body in general, not just the active forearm muscles.The stress load placed on the heart by piano playing can be at least as great as that produced by a brisk walk.Piano playing can generate an oxygen debt in the forearm muscles.Conditioning of forearm muscles through regular piano practice results in training effect for piano playing in those muscles.Pianists who participate regularly in quality aerobic exercise programs generally begin and end piano exercise with lower heart rates than those who do not exercise. Frequently, they increase heart rates to a lesser extent during exercise and settle into steady postexercise rates more quickly as well.Both regular piano practice and general cardiovascular conditioning gained through quality aerobic exercise contribute to increased piano-playing endurance.Acute smoking increases cardiac outputs and heart rates of pianists resulting in higher levels of cardiac work during piano exercise.During piano exercise, acutely smoking pianists require greatly increased forearm blood flows to meet muscle needs.
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Henry, Brad A. "STABILIZATION OF EXTENDED DIFFUSE OPTICAL SPECTROSCOPY MEASUREMENTS ON IN VIVO HUMAN SKELETAL MUSCLE DURING DYNAMIC EXERCISE." UKnowledge, 2014. http://uknowledge.uky.edu/cbme_etds/22.
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This research investigates various applications of diffuse correlation spectroscopy (DCS) on in-vivo human muscle tissue, both at rest and during dynamic exercise. Previously suspected muscle tissue relative blood flow (rBF) baseline shift during extended measurement with DCS and DCS-Near infrared spectroscopy (NIRS) hybrid optical systems are verified, quantified, and resolved by redesign of optical probe and alteration in optical probe attachment methodology during 40 minute supine bed rest baseline measurements. We then translate previously developed occlusion techniques, whereby rBF and relative oxygen consumption rV̇O2 are calibrated to initial resting absolute values by use of a venous occlusion (VO) and arterial occlusion (AO) protocol, respectively, to the lower leg (gastrocnemius) and these blood flows are cross validated at rest by strain gauge venous plethysmography (SGVP). Methods used to continuously observe 0.5Hz, 30% maximum voluntary isometric contraction (MVIC) plantar flexion exercise via dynamometer are adapted for our hybrid DCS-Imagent diffuse optical flow-oximeter in the medial gastrocnemius. We obtain healthy control muscle tissue hemodynamic profiles for key parameters BF, V̇O2, oxygen saturation (StO2), deoxyhemoglobin, oxyhemoglobin, and total hemoglobin concentrations ([Hb], [HbO2], and THC respectively), as well as systemic mean arterial pressure (MAP) and pulse rate (PR), at rest, during VO/AO, during dynamic exercise and during 15 minute recovery periods. Next, we began investigation of muscle tissue hemodynamic disease states by performing a feasibility pilot study using limited numbers of controls and peripheral arterial disease (PAD) patients using the translated methods/techniques to determine the ability of our technology to assess differences in these populations.
Books on the topic "Exercise flow rates"
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Lung volume subdivisions and expiratory flow rates in lean and moderately obese women: At rest and during two intensities of submaximal exercise. 1988.
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Lung volume subdivisions and expiratory flow rates in lean and moderately obese women: At rest and during two intensities of submaximal exercise. 1988.
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Lung volume subdivisions and expiratory flow rates in lean and moderately obese women at rest and during two intensities of submaximal exercise. 1988.
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Lung volume subdivisions and expiratory flow rates in lean and moderately obese women: At rest and during two intensities of submaximal exercise. 1986.
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Nixon, Patricia A. Pulmonary function. Oxford University Press, 2013. http://dx.doi.org/10.1093/med/9780199232482.003.0006.
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The focus of this chapter is the assessment and interpretation of pulmonary function during exercise in children, with emphasis on the parameters commonly measured in the paediatric setting. The measurements of resting pulmonary function (i.e. lung volumes and expiratory flow rates) are presented to provide the basic foundation for understanding changes that occur with exercise. Some measurements are more relevant to children with cardiopulmonary disorders, and examples of normal and abnormal responses are provided. In some instances, data on children are lacking, so responses of adults are presented.
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The relationship between skeletal muscle blood flow and blood lactate concentrations during exercise in rats. 1990.
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The relationships among exercise blood lactate response, muscle blood flow, and oxidative adaptation to endurance training in the rat. 1992.
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The relationships among exercise blood lactate response, muscle blood flow, and oxidative adaptation to endurance training in the rat. 1992.
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Differential control of blood flow to muscles composed predominantly of different fiber types. 1990.
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Differential control of blood flow to muscles composed predominantly of different fiber types. 1991.
Find full textBook chapters on the topic "Exercise flow rates"
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Wezenberg D., Houdijk J.H.P., van der Woude L.H.V., and de Haan A. "Continuous versus discontinuous protocols using a graded one-legged peak exercise test for lower limb amputees." In Assistive Technology Research Series. IOS Press, 2010. https://doi.org/10.3233/978-1-60750-080-3-222.
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Testing patients with a uni-lateral leg amputation using a graded one-legged peak exercise test (GOPET) poses difficulties. The smaller muscle mass results in increased intramuscular tension, thereby restricting blood flow to the active muscle. This ultimately leads to enhanced local fatigue in the active muscles. This is aggravated when vascular problems are present, such as often seen in persons who underwent amputation. This study investigated the influence of a discontinuous protocol when performing a GOPET in healthy participants. It is hypothesized that the resting phase following the exercise phase will restore blood flow, postponing local fatigue resulting in a higher measured aerobic capacity. Eight healthy participants performed three GOPET's: a continuous protocol (CON) and two discontinuous protocols in which an exercise phase of 60 (DIS60) or 90 s (DIS90) was followed by a 30 s rest period. No difference in aerobic capacity and peak heart rate were found among the three protocols. Peak workload and exercise duration were significantly higher in both discontinuous protocols compared to the continuous protocol. Subjectively, participants experienced the DIS protocols as more comfortable. A discontinuous protocol elicits similar aerobic capacities and peak heart rates, but higher peak workloads and lower discomfort, compared to a continuous protocol. Given the subjective preference, a discontinuous protocol may be advantageous over a continuous protocol, which may especially apply for patients with an amputation due to vascular problems.
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Kilner, Philip J., and Sonya V. Babu-Narayan. "The heart as a functional unit." In ESC CardioMed, edited by Yen Ho. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198784906.003.0015.
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This chapter and Chapter 3.6 address the interrelatedness of heart form, structure, and function. The principle of reciprocation between the alternate contractions of atrial and ventricular cavities is outlined, and it is explained how it is enhanced with the increased output of exercise by virtue of the directions of the forces associated with changes of momentum through the looped curvatures of the heart. The human heart’s sinuous paths of flow and its fully septated, four-chamber arrangement are features shared by the hearts of other mammals and the birds, which are also warm-blooded with relatively high cardiac outputs for high metabolic rates. These morphological features are not found among the hearts of the exothermic invertebrate phyla such as worms, arthropods, or molluscs. The possible evolutionary origins and potential functional advantages of cardiac septation for mammalian life are considered. This chapter addresses the interrelatedness of macroscopic structural morphodynamics with the fluid morphodynamics of passing blood streams while Chapter 3.6 considers the smaller-scale morphodynamics of myocardium in an attempt to convey a multiscale morphodynamic interpretation of the heart form, structure, and function.
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Kilner, Philip J., and Sonya V. Babu-Narayan. "The heart as a functional unit." In ESC CardioMed, edited by Yen Ho. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198784906.003.0015_update_001.
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This chapter and Chapter 3.6 address the interrelatedness of heart form, structure, and function. The principle of reciprocation between the alternate contractions of atrial and ventricular cavities is outlined, and it is explained how it is enhanced with the increased output of exercise by virtue of the directions of the forces associated with changes of momentum through the looped curvatures of the heart. The human heart’s sinuous paths of flow and its fully septated, four-chamber arrangement are features shared by the hearts of other mammals and the birds, which are also warm-blooded with relatively high cardiac outputs for high metabolic rates. These morphological features are not found among the hearts of the exothermic invertebrate phyla such as worms, arthropods, or molluscs. The possible evolutionary origins and potential functional advantages of cardiac septation for mammalian life are considered. This chapter addresses the interrelatedness of macroscopic structural morphodynamics with the fluid morphodynamics of passing blood streams while Chapter 3.6 considers the smaller-scale morphodynamics of myocardium in an attempt to convey a multiscale morphodynamic interpretation of the heart form, structure, and function.
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Peters, A. M., and M. J. Myers. "Exercises." In Physiological Measurements with Radionuclides in Clinical Practice. Oxford University PressNew York, NY, 1998. http://dx.doi.org/10.1093/oso/9780192619945.003.0014.
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Abstract During continuous infusion of bromosulphtha lein (BSP) at a rate of 1200 mg/min, the steady-state arterial concentration was 1 mg/ml and the hepatic venous BSP concentration was 0.2 mg/ml; what was liver blood flow? (Assume no extrahepatic uptake of BSP). A patient with a cardiac output of 5600 ml/min and a pulse rate of 70/min has a left ventricular ejection fraction of 0.64. What are the left ventricular end-diastolic and end-systolic volumes? Following injection of a labelled intravascular tracer, cerebral blood volume was found to be 75 ml; if cerebral blood flow was 250 ml/min, what was the mean cerebral vascular transit time? The area under an arterial fluorine-18 time concentration curve, recorded in a cerebral region of interest up to 10 min after bolus intravenous injection of fluorine-18-fluorodeoxyglucose (FDG), was 15 MBq•ml-1-min.
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Wray, Jo. "The Impact of Congenital Heart Disease on Cognitive and Behavioral Functioning." In Cognitive and Behavioral Abnormalities of Pediatric Diseases. Oxford University Press, 2010. http://dx.doi.org/10.1093/oso/9780195342680.003.0011.
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Congenital heart disease (CHD) has been defined as “. . . a gross structural abnormality of the heart or intrathoracic great vessels that is actually or potentially of functional significance” (Mitchell, Korones, and Berendes 1971). Congenital heart disease is the most common single group of congenital abnormalities, accounting for about 30% of the total. The incidence is reported as varying between 0.3% and 1% of all live births. Ten to 15% of children with congenital heart defects have more than one cardiac abnormality; up to one-third also have one or more associated noncardiac congenital abnormalities (Wernovsky 2006). Although some forms of CHD are minor and do not require any medical or surgical intervention, others are very complex and may necessitate a series of staged surgical procedures and/or require life-long medications. Significant improvements in medical and surgical techniques have resulted in increasing numbers of children and adults living with CHD, and it is currently anticipated that 80%–85% of children born with CHD today will survive into adulthood (British Cardiac Society 2002). However, although survival rates have improved dramatically over the last 40 years or so, morbidity remains a concern. Congenital heart defects can be broadly subdivided into two groups, based on changes in the circulation. Acyanotic defects may be due to either a left-to-right shunt or to an obstructive lesion; there is no mixing of desaturated blood in the systemic arterial circulation. With cyanotic defects, there may be either increased or diminished pulmonary flow, and desaturated blood enters the systemic arterial circulation, regardless of whether cyanosis is clinically evident. Unsaturated venous blood bypassing the lungs can result in secondary polycythemia, which is a compensatory mechanism to carry more oxygen to the tissues. This causes increased viscosity, which in turn results in sluggish blood circulation and impeded blood flow, particularly in the capillaries. Poor peripheral blood flow and clubbing of the fingers and toes can result, breathlessness and fatigue often result in a reduced exercise tolerance, and growth may be affected.
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Connes Philippe, Brun Jean-Frédéric, and Baskurt Oguz K. "Blood Rheology and Exercise." In Biomedical and Health Research. IOS Press, 2010. https://doi.org/10.3233/978-1-60750-497-9-213.
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Hemorheology is the science of the deformation and flow of blood and its formed elements (mainly red blood cells and to a lesser part white blood cells and platelets). This field includes investigating the bulk properties of blood, determined in viscometric experiments in macroscopic samples, and its microscopic properties. The present review will first consider the known and postulated effects of blood rheological properties on aerobic performance as related to its effects on oxygen delivery and second, the acute and long term effects of exercise on blood rheology. Blood and plasma viscosities are among main determinants of blood flow resistance both in macro- and microcirculation and of cardiac function. Red blood cell (RBC) deformability and local hematocrit have also been demonstrated to influence the oxygen diffusion capacity at the pulmonary and the muscular levels. At least, RBC aggregation properties may have either a negative or positive effect on blood flow, and thus on aerobic performance, depending on the orientation of the vessels, the shear rate in those vessels and the interaction of RBC aggregates with endothelium. During exercise, plasma viscosity and hematocrit usually increase leading to an increase of blood viscosity. Controversial results are frequently found about the influence of acute exercise on RBC deformability and aggregation, with some studies describing alterations, improvement or no changes, depending on the kind of exercise performed and on the population studied. The mechanisms underlying these changes might be attributed to white cell activation and/or lactic acid production. Also, we will discuss the effects of training, with aerobic training decreasing blood and plasma viscosities, lowering hematocrit and RBC aggregation, increasing RBC deformability.
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Ellestad, Myrvin H. "History of Stress Testing." In Stress Testing Principles and Practice. Oxford University PressNew York, NY, 2003. http://dx.doi.org/10.1093/oso/9780195159288.003.0001.
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Abstract The cornerstone of modern stress testing is based on the empirical discovery that exercise in patients with coronary disease produces ST-segment depression. This discovery might be credited to Bousfield, who recorded STsegment depression in the three standard ECG leads during a spontaneous attack of angina in 1918; or, it might be credited to Feil and Siegel, who, in 1928, actually exercised patients with known angina to bring about pain and, concurrently, the ST- and T-wave changes we now recognize as showing evidence of ischemia. These researchers described the changes as being due to a decrease in blood flow to the heart, and they published tracings showing a return to normal after the pain had subsided and also after administration of nitroglycerin. Feil and Siegel conducted their stress tests by having the patients do sit-ups; in selected cases, they held their hands on the patient’s chest to increase the resistance and therefore the energy required to perform this maneuver. Einthoven may have actually recognized the changes associated with ischemia. He published a tracing in 1908 showing ST-segment depression after exercise, but did not comment on this finding. Felberbaum and Finesilver probably published the first paper describing a step test in 1927. Using a footstool 12 inches high, they regulated the rate of stepping and monitored the heart rate before and after exercise.
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Magder, Sheldon. "Mechanical Limits of Cardiac Output at Maximal Aerobic Exercise." In Exercise Physiology [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.103908.
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This chapter uses an analytic approach to the factors limiting maximal aerobic exercise. A person’s maximal aerobic work is determined by their maximal oxygen consumption (VO2max). Cardiac output is the dominant determinant of VO2 and thus the primary determinant of population differences in VO2max. Furthermore, cardiac output is the product of heart rate and stroke volume and maximum heart rate is determined solely by a person’s age. Thus, maximum stroke volume is the major factor for physiological differences in aerobic performance. Stroke output must be matched by stroke volume return, which is determined by the mechanical properties of the systemic circulation. These are primarily the compliances of each vascular region and the resistances between them. I first discuss the physiological principles controlling cardiac output and venous return. Emphasis is placed on the importance of the distribution of blood flow between the parallel compliances of muscle and splanchnic beds as described by August Krogh in 1912. I then present observations from a computational modeling study on the mechanical factors that must change to reach known maximum cardiac outputs during aerobic exercise. A key element that comes out of the analysis is the role of the muscle pump in achieving high cardiac outputs.
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Price M., Bhogal R., Thake C.D., and Bottoms L.M. "Lower limb skin blood flow and calf volume changes during continuous and intermittent upper body exercise." In Assistive Technology Research Series. IOS Press, 2010. https://doi.org/10.3233/978-1-60750-080-3-94.
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Purpose: To determine the changes in thigh and calf skin blood flow during continuous and intermittent upper body exercise. Methods: Eight healthy able-bodied males undertook a preliminary incremental arm crank ergometry (ACE) test to volitional exhaustion and two experimental trials. Experimental trials consisted of either 28 min of continuous ACE at 50% peak power (CON) or 28 min intermittent exercise (INT) involving alternating 2 min bouts of ACE at 25% and 75% peak power. Changes in skin blood flow were measured by Laser Doppler techniques. Changes in calf volume were measured by strain gauge plethysmography. Heart rate and expired gas were continuously monitored. Aural and skin temperatures were measured. Results: Calf volume decreased in both trials, decreasing to a greater extent during INT (P&lt;0.05). Changes in skin blood flow of the thigh and calf demonstrated intensity dependent increases during INT whereas a more steady state increase was observed during CON. There were no differences in aural temperature between trials. Calf skin temperature decreased in both trials and to a greater extent during INT. Conclusions: Increases in skin blood flow occur concurrently with a decrease in calf volume. Additionally, changes in skin blood flow appear to change rapidly with changes in exercise intensity.
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Baskurt Oguz K. and Meiselman Herbert J. "Endothelial Function and Physical Activity." In Biomedical and Health Research. IOS Press, 2010. https://doi.org/10.3233/978-1-60750-497-9-230.
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Endothelium serves as the permeability barrier between the blood and interstitial space. Endothelial function includes the production, secretion and metabolisation of bio-active molecules. Endothelium also plays significant roles in cell migration, remodeling of the vasculature (including proliferation and apoptosis). Finally, endothelial function is an important effector in the regulatory processes of vascular tonus which in turn determines the flow resistance. The role of hemodynamic shear forces in modulating the endothelial function is now well established. Cardiac output and flow rate in the vasculature significantly increases during exercise, resulting in enhanced wall shear stress affecting on the endothelium. Alterations in endothelial function were demonstrated in response to various exercise protocols in human beings and also in various experimental animals. Blood rheology may also be affected by acute exercise episodes and training, with the potential of modulating endothelial function.
Conference papers on the topic "Exercise flow rates"
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Adey, Robert, Andres Peratta, John Baynham, and Thomas Curtin. "Using a Computational Galvanic Model in a Fracture Mechanics Framework to Improve Material Degradation Prediction." In CORROSION 2020. NACE International, 2020. https://doi.org/10.5006/c2020-14646.
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Abstract Although computational methods have been separately developed to predict corrosion and fatigue crack growth rates for metallic structures, challenges remain in implementing a methodology that considers the combined effects. In this work the output from a galvanic model is used to determine the spatial distribution of corrosion damage; providing a guide for the location of discrete corrosion damage features that can be analyzed using stress fields from structural models. In order to build confidence in this approach the galvanic models are validated by comparing predicted results to surface damage measurements from test specimens subject to ambient atmospheric exposure. There was good comparison between the predicted spatial distribution of corrosion damage and the measured surface damage profiles obtained from the galvanic test specimens. Following this exercise novel computational corrosion damage features were developed to represent simplified cracks shapes emanating from corrosion pits. Stress intensity factors (SIF) for these newly developed hybrid pit-crack features were determined and these solutions compared to cases where the pit is assumed to be an equivalent crack. The impact of the local, cavity induced stress field, on the SIF solutions is discussed. Building on these findings a fatigue crack growth simulation was performed using an initial flaw emanating from a hemispherical cavity (corrosion pit) located at the edge of hole in a plate. A reasonable comparison, of the predicted number of crack growth cycles, to available experimental test results was achieved.
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Adey, Robert, Andres Peratta, John Baynham, and Thomas Curtin. "Using a Computational Galvanic Model in a Fracture Mechanics Framework to Improve Material Degradation Prediction." In CORROSION 2021. AMPP, 2021. https://doi.org/10.5006/c2021-16509.
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ABSTRACT Although computational methods have been separately developed to predict corrosion and fatigue crack growth rates for metallic structures, challenges remain in implementing a methodology that considers the combined effects. In this work the output from a galvanic model is used to determine the spatial distribution of corrosion damage; providing a guide for the location of discrete corrosion damage features that can be analyzed using stress fields from structural models. In order to build confidence in this approach the galvanic models are validated by comparing predicted results to surface damage measurements from test specimens subject to ambient atmospheric exposure. There was good comparison between the predicted spatial distribution of corrosion damage and the measured surface damage profiles obtained from the galvanic test specimens. Following this exercise novel computational corrosion damage features were developed to represent simplified cracks shapes emanating from corrosion pits. Stress intensity factors (SIF) for these newly developed hybrid pit-crack features were determined and these solutions compared to cases where the pit is assumed to be an equivalent crack. The impact of the local, cavity induced stress field, on the SIF solutions is discussed. Building on these findings a fatigue crack growth simulation was performed using an initial flaw emanating from a hemispherical cavity (corrosion pit) located at the edge of hole in a plate. A reasonable comparison, of the predicted number of crack growth cycles, to available experimental test results was achieved.
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Vivodtzev, Isabelle, Erwan L'Her, Claire Yankoff, et al. "Automatically adjusted oxygen flow rates to stabilize oxygen saturation during exercise in O2-dependent and hypercapnic COPD." In ERS International Congress 2016 abstracts. European Respiratory Society, 2016. http://dx.doi.org/10.1183/13993003.congress-2016.pa1567.
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Monaco, Lucio, Damian M. Vogt, and Torsten H. Fransson. "Implementation of a Remote Pump Laboratory Exercise in the Training of Engineering Students." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-69983.
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The use of laboratory exercises in the training of engineering students is of paramount importance to give the students the possibility to gain practical experience on real hardware and on real test data. Recent trends in the education of engineers at the Department of Energy Technology at KTH go towards an increasing share of distant-based education, which is put in place to educate students at different geographic locations, not only locally (such as for example with engineers in industry) but also internationally (i.e. with students in different countries). In order to provide the possibility to follow a course at a distance without compromising on learning objectives and learning quality, a number of remotely operated laboratory exercises have been developed and implemented in the engineering curriculum at the department. Among these, to mention the work carried out by Navarathna et al. [11] on a remotely operated linear cascade test facility. The present laboratory exercise is integrated in a course on turbomachinery and gives the students the possibility to interactively learn about the operation of pumps at various speeds, various mass flow rates, parallel operation and serial operation. Students access the laboratory exercise using a web-based interface, perform measurements and finally have test data sent to an initially specified email address for further analysis.
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Arzani, Amirhossein, Ga Young Suh, Michael V. McConnell, Ronald L. Dalman, and Shawn C. Shadden. "Progression of Abdominal Aortic Aneurysm: Effect of Lagrangian Transport and Hemodynamic Parameters." In ASME 2013 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/sbc2013-14643.
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Abdominal aortic aneurysm (AAA) is a permanent, localized enlargement of the abdominal aorta that accompanies disturbed blood flow, which is thought to perpetuate aneurysm progression. AAA rupture is a leading cause of death in the elderly and an exact intervention decision for this disease has always been associated with uncertainty. There is currently no medicinal treatment of AAA, however lower extremity exercise has been a proposed therapy. Specifically, elevated flow rates in the abdominal aorta, reduced retrograde flow, higher mean wall shear stress, and lower oscillatory shear index resulting from exercise have been hypothesized as beneficial in preventing or slowing AAA. Computational fluid dynamics (CFD) has recently been used to model flow conditions inside AAA with an aim to better understand the biomechanical underpinnings of this disease. Recent studies have used patient-specific computational models, however few studies have looked in detail to AAA transport topology or correlated their results with aneurysm progression data. This study aims to (1) compare the flow topology between rest and exercise conditions in patients with small AAA to understand specifically how blood transport changes from rest to exercise, and (2) compare flow parameters obtained by CFD to the aneurysm progression.
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Lawrence, Edwin, Marie Bjoerdal Loevereide, Sanggeetha Kalidas, Ngoc Le Le, Sarjono Tasi Antoneus, and Tu Le Mai Khanh. "Production Optimization in Mature Field Through Scenario Prediction Using a Representative Network Model: A Rapid Solution Without Well Intervention." In SPE/IATMI Asia Pacific Oil & Gas Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205662-ms.
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Abstract As part of the production optimization exercise in J field, an initiative has been taken to enhance the field production target without well intervention. J field is a mature field; the wells are mostly gas lifted, and currently it is in production decline mode. As part of this optimization exercise, a network model with multiple platforms was updated with the surface systems (separator, compressors, pumps, FPSO) and pipelines in place to understand the actual pressure drop across the system. Modelling and calibration of the well and network model was done for the entire field, and the calibrated model was used for the production optimization exercise. A representative model updated with the current operating conditions is the key for the field production and asset management. In this exercise, a multiphase flow simulator for wells and pipelines has been utilized. A total of ∼50 wells (inclusive of idle wells) has been included in the network model. Basically, the exercise started by updating the single-well model using latest well test data. During the calibration at well level, several steps were taken, such as evaluation of historical production, reservoir pressure, and well intervention. This will provide a better idea on the fine-tuning parameters. Upon completion of calibrating well models, the next level was calibration of network model at the platform level by matching against the platform operating conditions (platform production rates, separator/pipeline pressure). The last stage was performing field network model calibration to match the overall field performance. During the platform stage calibration, some parameters such as pipeline ID, horizontal flow correlation, friction factor, and holdup factor were fine-tuned to match the platform level operating conditions. Most of the wells in J field have been calibrated by meeting the success criterion, which is within +/-5% for the production rates. However, there were some challenges in matching several wells due to well test data validity especially wells located on remote platform where there is no dedicated test separator as well as the impact of gas breakthrough, which may interfere to performance of wells. These wells were decided to be retested in the following month. As for the platform level matching, five platforms were matched within +/-10% against the reported production rates. During the evaluation, it was observed there were some uncertainties in the reported water and gas rates (platform level vs. well test data). This is something that can be looked into for a better measurement in the future. By this observation, it was suggested to select Platform 1 with the most reliable test data as well as the platform rate for the optimization process and qualifying for the field trial. Nevertheless, with the representative network model, two scenarios, reducing separator pressure at platform level and gas lift optimization by an optimal gas lift rate allocation, were performed. The model predicts that a separator pressure reduction of 30 psi in Platform 1 has a potential gain of ∼300 BOPD, which is aligned with the field results. Apart from that, there was also a potential savings in gas by utilizing the predicted allocated gas lift injection rate.
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Ellam, Darren J., Raymond J. Atkin, and William A. Bullough. "Appraisal of an ESF Radial Plate Clutch With Cooling Flow Using a NNF CFD Solver." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-1940.
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Abstract To aid the application of electro-structured fluid (ESF) devices, a virtual two plate radial clutch is examined in a pre-prototyping exercise to estimate the effect of a radial cooling flow on pre-set torque transmission. A throughflow of ESF will act to keep the fluid temperature under control making such devices more reliable over a wider operating range. The ESF is treated as a Bingham viscoplastic material and clutch behaviour is investigated under steady state isothermal conditions. The resulting two-dimensional non-Newtonian fluid (NNF) model is solved using a computational fluid dynamics (CFD) package. The results are partially verified using analytical analysis and compared with sparse experimental data. This work is expected to lead to a more complex CFD model for which analytical methods will not be available. Indications are that, for realistic rates of throughflow, torque transmission should not be overtly affected. Hence the cooling of slipping ESF clutches by throughflow can be contemplated.
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Konecni, Snezana, and Nathan K. Bultman. "Influence of CFD Analysis on the Design of Cooling Channels for the CCL Cavity for the Spallation Neutron Source." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-2079.
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Abstract Water flow in cooling channels was simulated using the computational fluid dynamics (CFD) code CFX4. Pressure drop in the cooling channels of the coupled-cavity linac (CCL) cavity was calculated. The effects of the manifold on the pressure drop were studied also. Reducing the pressure drop was a primary goal of this exercise that led to changing the cooling channel entrance regions. Results of this analysis were used in sizing pumps required for the cooling system. For the validation of the simplified numerical model, an experiment was performed to measure the pressure drop in the cooling channels for variable flow rate, using a flow loop. Deionized water was circulated through the test section with a pump and its flow rate was monitored with a turbine flow meter. Pressure was monitored with pressure transducers at five locations including a differential pressure transducer across the test section, and water temperature was taken at the exit of the pump. Pressure drop across the inlet and outlet of the test section was measured and recorded for different flow rates. Flow rate was also monitored and stored simultaneously. From the recorded data, an empirical correlation was derived to describe the pressure drop, dp, as a function of flow rate through the four cooling channels.
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Kara, Ceyda, Hang Yi, Ahmadreza Haghnegahdar, and Yu Feng. "Comparative Computational Fluid Dynamics Analysis of Pulmonary Airway Flow and Surgical Outcomes for a Patient with Tracheal Stenosis." In 2025 Design of Medical Devices Conference. American Society of Mechanical Engineers, 2025. https://doi.org/10.1115/dmd2025-1083.
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Abstract Tracheal stenosis, a severe airway narrowing, poses significant challenges in respiratory function and often necessitates surgical intervention to restore proper airflow. This study aims to demonstrate how computational fluid dynamics (CFD) can provide a non-invasive, efficient, and highly individualized approach to assist surgeons in modeling and planning various surgical strategies for treatment. The CFD-based approach in this study provides significant advantages, including reduced time and cost, and the ability to analyze complex pulmonary airflow characteristics that are difficult to investigate using in vitro and in vivo studies. This research compares three tracheal geometries: a diseased airway with tracheal stenosis and two post-surgical configurations from different surgical plans. Simulations were conducted under four inhalation flow rates, i.e., rest (6 L/min), normal (30 L/min), moderate (60 L/min), and intensive exercise (120 L/min), to evaluate the impact of surgical outcomes on pulmonary airflow dynamics. The upper airway, modeled with a mouth inlet diameter of 20 mm, exhibited average velocities of 0.32, 1.59, 3.18, and 6.37 m/s, corresponding to the respective flow rates. The laminar model was used for the rest flow rate, while the shear stress transport (SST) k-ω model was applied to simulate turbulence with higher inhalation flow rates. The results revealed substantial improvements in flow parameters following surgery. The stenotic geometry exhibited extreme resistance, with pressure drops increasing from 1.96 Pa at rest to 318.9 Pa under intensive flow, and high wall shear stress (WSS) values peaking at 330.8 Pa. Surgical Plan 1 reduced pressure drops by up to 47% and WSS by 97%, while Surgical Plan 2 achieved even greater reductions, with pressure drops lowered by 45% and WSS reduced to 2.54 Pa under high flow rates. Localized flow disturbances, such as uneven airflow distribution among lung lobes, were also alleviated post-surgery. In the diseased airway, the right lower lobe received up to 40% of the total flow, causing severe imbalances. Surgical Plan 2 achieved the most uniform distribution, with all lobes receiving 13%-29% of airflow across all flow rates, ensuring effective oxygenation and minimizing risks of overdistension or under-perfusion. These findings suggest that the CFD-based approach employed in this study can effectively model surgical outcomes, providing surgeons with a fast, detailed, and non-invasive tool for tailoring procedures to individual patient needs.
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Almannai, Mohammed, and Muhammad Javed. "Method to Operate Water Wells at Optimum Rates Utilizing Orifice Performance Curves." In Middle East Oil, Gas and Geosciences Show. SPE, 2023. http://dx.doi.org/10.2118/213759-ms.
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Abstract Wells, e.g., water wells (injectors, disposal and supply) operate at designated rates set by reservoir engineers. The objective of producing/injecting these wells at optimum rates is to prolong the well's and reservoir's life. To effectively apply the mentioned objective, each well is assigned a target by the reservoir engineer to either produce or inject. Wells meeting this assigned target are called "compliant" wells while wells that do not meet the set target, whether above or below the target with a specified margin, are classified as "noncompliant" wells. This paper discusses a unique method that will significantly help in maintaining assigned target rates for water wells. The method is applicable to wells that are equipped with intelligent field equipment (DAS—data acquisition system) to monitor the wells in real time. All these wells are equipped with a specific size of orifice plate that maintains a differential pressure (dP), subsequently enabling the flowmeter to read a rate at that point of restriction in the orifice. Each orifice plate, depending on its dimensions, can have its very own orifice performance curve (OPC), which is generated based on multiple parameters. The OPC reflects dP (differential pressure) on its x-axis and flow rate on its y-axis, these curves are beneficial to be used while maintaining the well's target rate. Once a target rate is assigned by the reservoir engineer, a production engineer reviews the OPC and defines the required dP to be communicated for direct field implementation. By this exercise, targeted rates can be obtained without any back and forth communication or field visits for the ultimate goal of achieving compliance in water wells.
Reports on the topic "Exercise flow rates"
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Suksom, Daroonwan, Jettanong Klaewsongkram, Wannaporn Tongtako, and Nutdanai Jaronsukwimal. Effect of acute exercises, chronic exercise training and vitamin C supplementation on physiological change and symptoms in allegic rhinitis patients. Chulalongkorn University, 2013. https://doi.org/10.58837/chula.res.2013.72.
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The aim of this present study was to investigate an effect of acute exhaustive and moderate intensities exercises, exercise training and vitamin C supplementation on physiological change and rhinitis symptoms in allergic rhinitis patients. There were two studies: Study I : The subjects, aged18-45 years old, were divided into 2 groups: 14 healthy individuals and 13 allergic rhinitis (AR) patients. They were assigned to perform the strenuous exercise on treadmill by using Bruce protocol until they were exhausted. Two weeks later, they were assigned to perform a moderate exercise by walking on treadmill for 30 minutes at 65-70% of heart rate reserve (HRR). Study II: Twenty-seven volunteered patients with allergic rhinitis, aged 18-45 years old, were recruited. They were randomized into 3 groups: control group (CON; n=8), exercise group (EX; n=9) exercise combined with vitamin C group (EX + Vit. C; n=10). The exercise training protocol consisted of walking – running on a treadmill at 65-70% HRR, 30 minutes per session, 3 times a week. The EX + Vit. C group ingested vitamin C 2, 000 mg per day. Results of the study are as follow: Study I: After both acute exhaustive and moderate intensities exercises, volume of nasal inspiratory flow were increased but nasal congestion was decreased (p<.05). In addition, nasal blood flow was decreased after performing moderate exercise in both groups of subjects (p<.05). The ratio of IL-2 and IL-4 (IL-2/IL-4) after moderate exercise was significantly higher than exhaustive exercise in both the healthy and AR groups (p<0.05) Study II: After 8 weeks, malondialdehyde (MDA) levels of the both EX and EX + Vit. C were significantly lower than the CON group (p<.05). the both EX and EX + Vit. C had significantly lower in interleukin (IL)-4 levels but higher in IL-2 than the CON (p<.05). After nasal challenge by house dust mite (D.pteronyssinus), the percent difference of IL-4 and IL-13 were significantly lower but the percent difference of IL-2 were significantly higher in the both EX and EX + Vit C when compared with the CON (p<.05). For rhinitis symptoms, the percent difference of peak nasal inspiratory flow (PNIF) were significantly higher while nasal blood flow were significantly lower in the both EX and EX + Vit. C comparing to the CON (p<.05). Moreover, the both EX and EX + Vit. C had a significantly higher PNIF after nasal challenge 60 minutes comparing to pre-test (p<.05). The rhinitis symptoms score i.e. congestion, itching, sneezing, rhinorrhea and total symptoms at baseline and following nasal challenge were significantly decreased in the both EX and EX + Vit. C (p<.05). In conclusion, acute exhaustive and moderate intensities exercises increased peak nasal inspiratory flow and decreased nasal congestion in allergic rhinitis patients. But only moderate exercise also reduced nasal blood flow in allergic rhinitis patients. Eight weeks of moderate exercise training with and without vitamin C supplementation demonstrated improving cardiorespiratory fitness, attenuating the inflammatory response and reducing symptoms in patients with allergic rhinitis. Therefore, regularly moderate exercise training should be recommend for allergic rhinitis patients.
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Patumraj, Suthiluk, and Sheepsumon Viboolvorakul. Protective effects of exercise training against vascular and neuronal dysfunction in aging brain. Department of Physiology, Faculty of Medicine, Chulalongkorn University, 2019. https://doi.org/10.58837/chula.res.2019.11.
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During advancing age, reduction of microvessels in the brain contributes insufficiency tissue perfusion. Mounting evidence indicates that microvascular deterioration in aged brain relates to oxidative stress. Nuclear factor erythroid-related factor 2 (Nrf2) plays an important role in cellular antioxidant defense. Regular physical exercise is well known to have beneficial effect to brain health, including promoted blood flow and augmented angiogenesis, in aging individuals. However, the underlying mechanism of regular physical exercise in improvement of brain microvascular density during advancing age has not been fully elucidated. This study aimed to investigate the underlying mechanism of exercise training in improvement of microvascular density associated with PI3K/Akt/Nrf2 pathway in aged rat brain. Male Wistar rats were divided into three groups; sedentary-young (SY), sedentary-age (SA) and trained-age (TA). Exercise program included swimming exercise for eight weeks. Expression of CD31 (as indicator of microvascular density) and Nrf2 were evaluated by immunohistochemistry staining. Activity of Nrf2, protein levels of phosphatidylinositol-4,5-biphosphate 3-kinase (PI3K) and phosphorylated-protein kinase B (p-Akt) in isolated brain microvessels were assessed by immunoassay. Aging (SA) induced significant reduction of brain microvascular density and expression of Nrf2, PI3K and p-Akt proteins, as well as Nrf2 activity, comparing to those of SY group. The eight-week exercise training significantly improved brain microvascular density and upregulated Nrf2, PI3K and p-Akt proteins as well as activated Nrf2 activity, than that of the age group without exercise (SA). In conclusion, exercise training can improve brain microvascular deterioration associated with PI3K/Akt/Nrf2 pathway in aging rats.
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Suksom, Daroonwan, Chaicharn Deerochanawong, Tanaka, Hirofumi, and Witid Mitranun. The comparison effects of aerobic continuous training and aerobic interval training on glycemic control and endothelial function in type 2 diabetes mellitus. Chulalongkorn University, 2013. https://doi.org/10.58837/chula.res.2013.71.
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The objective of this study was to compare the effects of continuous aerobic exercise training (CON) and interval aerobic exercise training (INT) on glycemic control and endothelium-dependent vasodilatation in patients with type 2 diabetes. A total of 43 participants with type 2 diabetes aged 50-70 years were stratified in parallel-group study and randomly allocated to the sedentary control, continuous aerobic training (CON), and interval aerobic training ( INT) groups. Exercise training programs were designed to yield the same energy expenditure/exercise session and included walking on treadmill for 30 or 40 minutes/day, 3 times/week for 12 weeks. Biological variables, health-related physical fitness, endothelial function and biochemistry variables between pre-test and post-test were analyzed by a paired t-test. One way analysis of variance was used to compare the variables among groups. Differences were considered to be significant at p < .05. The results of the present study were as follow : 1. Body mass, BMI, body fatness, waist-to-hip ratio, and heart rate at rest decreased and leg muscle mass and muscle strength increased (all p<0.05) significantly in both the CON and INT groups when compared with pre-test. 2. Fasting blood glucose and insulin resistance levels decreased (p<0.05) in both exercise groups but glycosylated hemoglobin levels decreased (p<0.05) significantly only in the INT group when compared with pre-test. 3. Maximal aerobic capacity, flow-mediated dilation, and cutaneous blood flow increased (all p<0.05) significantly in both exercise groups; however, the magnitude of improvement was greater (p<0.05) significantly in the INT group. 4. Malondialdehyde and von Willebrand factor decreased and glutathione peroxidase and nitric oxide increased significantly (all p<0.05) in the INT group. CON group showed no significant changes in these parameters. In conclusion, Both CON and INT were effective in improving glycemic control, aerobic fitness, and endothelium-dependent vasodilation, but the INT program appears to confer greater improvements than the CON program.
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De Brun, Julio. Growth in Uruguay: Factor Accumulation or Productivity Gains? Inter-American Development Bank, 2004. http://dx.doi.org/10.18235/0008730.
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This paper is part of the project "Explaining Economic Growth Performance" launched by the Global Development Network (GDN). The purpose of this project is to explain economic growth performances across seven regions. During the last five decades the Uruguayan economy faced volatile macroeconomic conditions. Economic policies swung from highly controlled capital flows, exchange rates, and interest rates to the introduction of significant financial liberalization. This study will show that the upturn in economic growth since liberalization is due to improved resource allocation that, in turn, promoted an increase in human capital accumulation. No significant changes are observed in the pattern of physical capital accumulation or the evolution of Total Factor Productivity (TFP). The analysis begins with an overview of recent economic policy in Uruguay, summarizing the characteristics of each period. A growth accounting exercise is then conducted to begin weighing which factors are crucial to understanding the country's pattern of growth. This exercise will show, as previously stated, that TFP played a minimal role. This evidence is complemented by analysis of a time series of key variables, which permits us to address the empirical regularities that must be explained to understand economic growth in Uruguay.
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Brosh, Arieh, David Robertshaw, Yoav Aharoni, Zvi Holzer, Mario Gutman, and Amichai Arieli. Estimation of Energy Expenditure of Free Living and Growing Domesticated Ruminants by Heart Rate Measurement. United States Department of Agriculture, 2002. http://dx.doi.org/10.32747/2002.7580685.bard.
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Research objectives were: 1) To study the effect of diet energy density, level of exercise, thermal conditions and reproductive state on cardiovascular function as it relates to oxygen (O2) mobilization. 2) To validate the use of heart rate (HR) to predict energy expenditure (EE) of ruminants, by measuring and calculating the energy balance components at different productive and reproductive states. 3) To validate the use of HR to identify changes in the metabolizable energy (ME) and ME intake (MEI) of grazing ruminants. Background: The development of an effective method for the measurement of EE is essential for understanding the management of both grazing and confined feedlot animals. The use of HR as a method of estimating EE in free-ranging large ruminants has been limited by the availability of suitable field monitoring equipment and by the absence of empirical understanding of the relationship between cardiac function and metabolic rate. Recent developments in microelectronics provide a good opportunity to use small HR devices to monitor free-range animals. The estimation of O2 uptake (VO2) of animals from their HR has to be based upon a consistent relationship between HR and VO2. The question as to whether, or to what extent, feeding level, environmental conditions and reproductive state affect such a relationship is still unanswered. Studies on the basic physiology of O2 mobilization (in USA) and field and feedlot-based investigations (in Israel) covered a , variety of conditions in order to investigate the possibilities of using HR to estimate EE. In USA the physiological studies conducted using animals with implanted flow probes, show that: I) although stroke volume decreases during intense exercise, VO2 per one heart beat per kgBW0.75 (O2 Pulse, O2P) actually increases and measurement of EE by HR and constant O2P may underestimate VO2unless the slope of the regression relating to heart rate and VO2 is also determined, 2) alterations in VO2 associated with the level of feeding and the effects of feeding itself have no effect on O2P, 3) both pregnancy and lactation may increase blood volume, especially lactation; but they have no effect on O2P, 4) ambient temperature in the range of 15 to 25°C in the resting animal has no effect on O2P, and 5) severe heat stress, induced by exercise, elevates body temperature to a sufficient extent that 14% of cardiac output may be required to dissipate the heat generated by exercise rather than for O2 transport. However, this is an unusual situation and its affect on EE estimation in a freely grazing animal, especially when heart rate is monitored over several days, is minor. In Israel three experiments were carried out in the hot summer to define changes in O2P attributable to changes in the time of day or In the heat load. The animals used were lambs and young calves in the growing phase and highly yielding dairy cows. In the growing animals the time of day, or the heat load, affected HR and VO2, but had no effect on O2P. On the other hand, the O2P measured in lactating cows was affected by the heat load; this is similar to the finding in the USA study of sheep. Energy balance trials were conducted to compare MEI recovery by the retained energy (RE) and by EE as measured by HR and O2P. The trial hypothesis was that if HR reliably estimated EE, the MEI proportion to (EE+RE) would not be significantly different from 1.0. Beef cows along a year of their reproductive cycle and growing lambs were used. The MEI recoveries of both trials were not significantly different from 1.0, 1.062+0.026 and 0.957+0.024 respectively. The cows' reproductive state did not affect the O2P, which is similar to the finding in the USA study. Pasture ME content and animal variables such as HR, VO2, O2P and EE of cows on grazing and in confinement were measured throughout three years under twenty-nine combinations of herbage quality and cows' reproductive state. In twelve grazing states, individual faecal output (FO) was measured and MEI was calculated. Regression analyses of the EE and RE dependent on MEI were highly significant (P<0.001). The predicted values of EE at zero intake (78 kcal/kgBW0.75), were similar to those estimated by NRC (1984). The EE at maintenance condition of the grazing cows (EE=MEI, 125 kcal/kgBW0.75) which are in the range of 96.1 to 125.5 as presented by NRC (1996 pp 6-7) for beef cows. Average daily HR and EE were significantly increased by lactation, P<0.001 and P<0.02 respectively. Grazing ME significantly increased HR and EE, P<0.001 and P<0.00l respectively. In contradiction to the finding in confined ewes and cows, the O2P of the grazing cows was significantly affected by the combined treatments (P<0.00l ); this effect was significantly related to the diet ME (P<0.00l ) and consequently to the MEI (P<0.03). Grazing significantly increased O2P compared to confinement. So, when EE of grazing animals during a certain season of the year is estimated using the HR method, the O2P must be re measured whenever grazing ME changes. A high correlation (R2>0.96) of group average EE and of HR dependency on MEI was also found in confined cows, which were fed six different diets and in growing lambs on three diets. In conclusion, the studies conducted in USA and in Israel investigated in depth the physiological mechanisms of cardiovascular and O2 mobilization, and went on to investigate a wide variety of ruminant species, ages, reproductive states, diets ME, time of intake and time of day, and compared these variables under grazing and confinement conditions. From these combined studies we can conclude that EE can be determined from HR measurements during several days, multiplied by O2P measured over a short period of time (10-15 min). The study showed that RE could be determined during the growing phase without slaughtering. In the near future the development microelectronic devices will enable wide use of the HR method to determine EE and energy balance. It will open new scopes of physiological and agricultural research with minimizes strain on animals. The method also has a high potential as a tool for herd management.
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Panek, Jeffrey, Adrian Huth, and Benjamin Shwaiko. PR-312-22200-Z01 Isolation Valve - Improved GHG Leak Detection Summary of Initial Testing Results. Pipeline Research Council International, Inc. (PRCI), 2024. http://dx.doi.org/10.55274/r0000077.
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This project investigated and evaluated commercially available optical IR and acoustic technologies. The IR cameras were used to detect a temperature differential across the valve indicating a Joule-Thompson (JT) pressure drop and leak through the valve. Direct acoustically coupled instruments were used to detect "noise" generated from turbulence associated with through-valve leakage. In addition, other instruments were explored that had the potential to detect turbulence-induced vibrations. During the instrumentation evaluation, fugitive leak screening and detection methods for assessing through-valve leakage were also explored. IES completed a one-week laboratory and yard testing exercise on a single two- and eight-inch valve at the SoCal Gas Situation City facility in Pico Rivera, CA in November 2022. Noteworthy findings included the inability to detect a leak from valves that were previously in-service and known leakers. The reason for this has been hypothesized as improper valve stop position and/or debris in the valve that was removed to protect flow-rate measurement instrumentation in the test apparatus. Several instances of newly commissioned leaking valves have been shown to suffer from incorrect valve positioning and/or electronic transducer signal set points. Additional testing and data collection are needed to complete the initial test campaign. Outdoor testing could not be completed during the week due to resource limitations that precluded testing more than one eight-inch valve. The initial laboratory testing included one 2-inch test valve that had no discernable usage. An additional 2-inch valve was screened prior to lab testing, however neither valve produced a leak under the conditions in the lab (both valves failed prior to commissioning).
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Michel, Bob, and Tatiana Falcão. Taxing Profits from International Maritime Shipping in Africa: Past, Present and Future of UN Model Article 8 (Alternative B). Institute of Development Studies (IDS), 2021. http://dx.doi.org/10.19088/ictd.2021.023.
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International maritime shipping is an essential part of global business. Since the establishment of the current international tax regime in the 1920s, there has been a consensus that profits generated by this business are taxable only in the residence state –the state where the shipowners are located. Source states – the port states where business physically takes place – are generally expected to exempt income from international shipping. This standard is currently reflected in Article 8 of the OECD Model and Article 8 (Alternative A) of the UN Model, and is incorporated in the vast majority of bilateral tax treaties currently in force. Exclusive residence state taxation of shipping profits is problematic when the size of mercantile fleets and shipping flows between two states are of unequal size. This is often the case in relations between a developed and developing country. The latter often lack a substantial domestic mercantile fleet, but serve as an important revenue-generating port state for the fleet of the developed country. To come to a more balanced allocation of taxing rights in such a case, a source taxation alternative has been inserted in UN Model Article 8 (Alternative B). From its inception, Article 8B has been labelled impractical due to the lack of guidance on core issues, like sourcing rules and profit allocation. This gap is said to explain the low adoption rate of Article 8B in global tax treaty practice. In reality, tax treaty practice regarding Article 8B is heavily concentrated and flourishing in a handful of countries in South/South-East Asia – Bangladesh, India, Indonesia, Myanmar, Pakistan, the Philippines, Sri Lanka and Thailand. All these countries subject non-resident shipping income to tax in their domestic income tax laws. Except for India, all countries are able to exercise these domestic tax law rules in relation to shipping enterprises located in the biggest shipowner states, either because they have a treaty in place that provides for source taxation or because there is no treaty at all and thus no restriction of domestic law. None of the relevant tax treaties contain a provision that incorporates the exact wording of Article 8B of the UN Model. If other countries, like coastal countries in sub-Saharan Africa, are looking to implement source taxation of maritime shipping income in the future, they are advised to draw on the South/South-East Asian experience. Best practice can be distilled regarding sourcing rule, source tax limitation, profit attribution and method of taxation (on gross or net basis). In addition to technical guidance on tax, the South/South-East Asian experience also provides important general policy considerations countries should take into account when determining whether source taxation of maritime shipping profits is an appropriate target for their future tax treaty negotiations.
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Financial Stability Report - Second Semester of 2021. Banco de la República, 2022. http://dx.doi.org/10.32468/rept-estab-fin.sem2.eng-2021.
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Banco de la República’s main objective is to preserve the purchasing power of the currency in coordination with the general economic policy that is intended to stabilize output and employment at long-term sustainable levels. Properly meeting the goal assigned to the Bank by the 1991 Constitution critically depends on preserving financial stability. This is understood to be a general condition in which the financial system assesses and manages the financial risks in a way that facilitates the economy’s performance and efficient allocation of resources while, at the same time, it is able to, on its own, absorb, dissipate, and mitigate the shocks that may arise as a result of adverse events. This Financial Stability Report meets the goal of giving Banco de la República’s diagnosis of the financial system’s and its debtors’ recent performance as well as of the main risks and vulnerabilities that could affect the stability of the Colombian economy. In this way, participants in financial markets and the public are being informed, and public debate on trends and risks affecting the system is being encouraged. The results presented here also serve the monetary authority as a basis for making decisions that will enhance financial stability in the general context of its objectives. In recent months, several positive aspects of the financial system have preserved a remarkable degree of continuity and stability: the liquidity and capital adequacy of financial institutions have remained well above the regulatory minimums at both the individual and consolidated levels, the coverage of past-due loans by loan-loss provisions remains high, and the financial markets for public and private debt and stocks have continued to function normally. At the same time, a surge in all the types of loan portfolios, a sharp downturn in the non-performing loan portfolio, and a rise in the profitability of credit institutions can be seen for the first time since the beginning of the pandemic. In line with the general recovery of the economy, the main vulnerability to the stability of the Colombian financial system identified in the previous edition—uncertainty about changes in the non-performing loans portfolio—has receded and remains on a downward trend. In this edition, the main source of vulnerability identified for financial stability in the short term is the system’s exposure to sudden changes in international financial conditions; the results presented in this Report indicate that the system is sufficiently resilient to such scenarios. In compliance with its constitutional objectives and in coordination with the financial system’s security network, Banco de la República will continue to closely monitor the outlook for financial stability at this juncture and will make the decisions necessary to ensure the proper functioning of the economy, facilitate the flow of sufficient credit and liquidity resources, and further the smooth functioning of the payment system. Leonardo Villar Gomez Governor Box 1 -Decomposition of the Net Interest Margin in Colombia and Chile Wilmar Cabrera Daniela Rodríguez-Novoa Box 2 - Spatial Analysis of New Home Prices in Bogota, Medellín, and Cali Using a Geostatistical Approach María Fernanda Meneses Camilo Eduardo Sánchez Box 3 - Interest Rate Model for the SYSMO Stress Test Exercise Wilmar Cabrera Diego Cuesta Santiago Gamba Camilo Gómez Box 4 - The Transition from LIBOR and other International Benchmark Rates Daniela X. Gualtero Briceño Javier E. Pirateque Niño
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Financial Stability Report - Second Semester of 2020. Banco de la República de Colombia, 2021. http://dx.doi.org/10.32468/rept-estab-fin.sem2.eng-2020.
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The Colombian financial system has not suffered major structural disruptions during these months of deep economic contraction and has continued to carry out its basic functions as usual, thus facilitating the economy's response to extreme conditions. This is the result of the soundness of financial institutions at the beginning of the crisis, which was reflected in high liquidity and capital adequacy indicators as well as in the timely response of various authorities. Banco de la República lowered its policy interest rates 250 points to 1.75%, the lowest level since the creation of the new independent bank in 1991, and provided ample temporary and permanent liquidity in both pesos and foreign currency. The Office of the Financial Superintendent of Colombia, in turn, adopted prudential measures to facilitate changes in the conditions for loans in effect and temporary rules for rating and loan-loss provisions. Finally, the national government expanded the transfers as well as the guaranteed credit programs for the economy. The supply of real credit (i.e. discounting inflation) in the economy is 4% higher today than it was 12 months ago with especially marked growth in the housing (5.6%) and commercial (4.7%) loan portfolios (2.3% in consumer and -0.1% in microloans), but there have been significant changes over time. During the first few months of the quarantine, firms increased their demands for liquidity sharply while consumers reduced theirs. Since then, the growth of credit to firms has tended to slow down, while consumer and housing credit has grown. The financial system has responded satisfactorily to the changes in the respective demands of each group or sector and loans may grow at high rates in 2021 if GDP grows at rates close to 4.6% as the technical staff at the Bank expects; but the forecasts are highly uncertain. After the strict quarantine implemented by authorities in Colombia, the turmoil seen in March and early April, which was evident in the sudden reddening of macroeconomic variables on the risk heatmap in Graph A,[1] and the drop in crude oil and coal prices (note the high volatility registered in market risk for the region on Graph A) the local financial markets stabilized relatively quickly. Banco de la República’s credible and sustained policy response played a decisive role in this stabilization in terms of liquidity provision through a sharp expansion of repo operations (and changes in amounts, terms, counterparties, and eligible instruments), the purchases of public and private debt, and the reduction in bank reserve requirements. In this respect, there is now abundant aggregate liquidity and significant improvements in the liquidity position of investment funds. In this context, the main vulnerability factor for financial stability in the short term is still the high degree of uncertainty surrounding loan quality. First, the future trajectory of the number of people infected and deceased by the virus and the possible need for additional health measures is uncertain. For that reason, there is also uncertainty about the path for economic recovery in the short and medium term. Second, the degree to which the current shock will be reflected in loan quality once the risk materializes in banks’ financial statements is uncertain. For the time being, the credit risk heatmap (Graph B) indicates that non-performing and risky loans have not shown major deterioration, but past experience indicates that periods of sharp economic slowdown eventually tend to coincide with rises in non-performing loans: the calculations included in this report suggest that the impact of the recession on credit quality could be significant in the short term. This is particularly worrying since the profitability of credit establishments has been declining in recent months, and this could affect their ability to provide credit to the real sector of the economy. In order to adopt a forward-looking approach to this vulnerability, this Report presents several stress tests that evaluate the resilience of the liquidity and capital adequacy of credit institutions and investment funds in the event of a hypothetical scenario that seeks to simulate an extreme version of current macroeconomic conditions. The results suggest that even though there could be strong impacts on the credit institutions’ volume of credit and profitability under such scenarios, aggregate indicators of total and core capital adequacy will probably remain at levels that are above the regulatory limits over the horizon of a year. At the same time, the exercises highlight the high capacity of the system's liquidity to face adverse scenarios. In compliance with its constitutional objectives and in coordination with the financial system's security network, Banco de la República will continue to closely monitor the outlook for financial stability at this juncture and will make the decisions that are necessary to ensure the proper functioning of the economy, facilitate the flow of sufficient credit and liquidity resources, and further the smooth operation of the payment systems. Juan José Echavarría Governor