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Готові списки джерел за темами / Muscle deoxygenation / Статті в журналах

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Статті в журналах з теми "Muscle deoxygenation"

Автор: Grafiati

Опубліковано: 10 січня 2023

Оновлено: 28 січня 2023

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1

Goulding, Richie P., Dai Okushima, Simon Marwood, David C. Poole, Thomas J. Barstow, Tze-Huan Lei, Narihiko Kondo, and Shunsaku Koga. "Impact of supine exercise on muscle deoxygenation kinetics heterogeneity: mechanistic insights into slow pulmonary oxygen uptake dynamics." Journal of Applied Physiology 129, no. 3 (September 1, 2020): 535–46. http://dx.doi.org/10.1152/japplphysiol.00213.2020.

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Анотація:

We show that supine exercise causes a greater degree of muscle deoxygenation in both deep and superficial muscle and increases the spatial heterogeneity of muscle deoxygenation. Therefore, this study suggests that any O2 delivery gradient toward deep versus superficial muscle is insufficient to mitigate impairments in oxidative function in response to reduced whole muscle O2 delivery. More heterogeneous muscle deoxygenation is associated with slower V̇o2 kinetics.

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2

Koga, Shunsaku, Yutaka Kano, Thomas J. Barstow, Leonardo F. Ferreira, Etsuko Ohmae, Mizuki Sudo, and David C. Poole. "Kinetics of muscle deoxygenation and microvascular Po2 during contractions in rat: comparison of optical spectroscopy and phosphorescence-quenching techniques." Journal of Applied Physiology 112, no. 1 (January 1, 2012): 26–32. http://dx.doi.org/10.1152/japplphysiol.00925.2011.

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Анотація:

The overarching presumption with near-infrared spectroscopy measurement of muscle deoxygenation is that the signal reflects predominantly the intramuscular microcirculatory compartment rather than intramyocyte myoglobin (Mb). To test this hypothesis, we compared the kinetics profile of muscle deoxygenation using visible light spectroscopy (suitable for the superficial fiber layers) with that for microvascular O2 partial pressure (i.e., PmvO2, phosphorescence quenching) within the same muscle region (0.5∼1 mm depth) during transitions from rest to electrically stimulated contractions in the gastrocnemius of male Wistar rats ( n = 14). Both responses could be modeled by a time delay (TD), followed by a close-to-exponential change to the new steady level. However, the TD for the muscle deoxygenation profile was significantly longer compared with that for the phosphorescence-quenching PmvO2 [8.6 ± 1.4 and 2.7 ± 0.6 s (means ± SE) for the deoxygenation and PmvO2, respectively; P < 0.05]. The time constants (τ) of the responses were not different (8.8 ± 4.7 and 11.2 ± 1.8 s for the deoxygenation and PmvO2, respectively). These disparate (TD) responses suggest that the deoxygenation characteristics of Mb extend the TD, thereby increasing the duration (number of contractions) before the onset of muscle deoxygenation. However, this effect was insufficient to increase the mean response time. Somewhat differently, the muscle deoxygenation response measured using near-infrared spectroscopy in the deeper regions (∼5 mm depth) (∼50% type I Mb-rich, highly oxidative fibers) was slower (τ = 42.3 ± 6.6 s; P < 0.05) than the corresponding value for superficial muscle measured using visible light spectroscopy or PmvO2 and can be explained on the basis of known fiber-type differences in PmvO2 kinetics. These data suggest that, within the superficial and also deeper muscle regions, the τ of the deoxygenation signal may represent a useful index of local O2 extraction kinetics during exercise transients.

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3

Lusina, Sarah-Jane C., Darren E. R. Warburton, Nicola G. Hatfield, and A. William Sheel. "Muscle deoxygenation of upper-limb muscles during progressive arm-cranking exercise." Applied Physiology, Nutrition, and Metabolism 33, no. 2 (April 2008): 231–38. http://dx.doi.org/10.1139/h07-156.

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Анотація:

The purpose of this study was to determine which upper-limb muscle exhibits the greatest change in muscle deoxygenation during arm-cranking exercise (ACE). We hypothesized that the biceps brachii (BB) would show the greatest change in muscle deoxygenation during progressive ACE to exhaustion relative to triceps brachii (TR), brachioradialis (BR), and anterior deltoid (AD). Healthy young men (n = 11; age = 27 ± 1 y; mean ± SEM) performed an incremental ACE test to exhaustion. Near-infrared spectroscopy (NIRS) was used to monitor the relative concentration changes in oxy- (O2Hb), deoxy- (HHb), and total hemoglobin (Hbtot), as well as tissue oxygenation index (TOI) in each of the 4 muscles. During submaximal arm exercise, we found that changes to NIRS-derived measurements were not different between the 4 muscles studied (p > 0.05). At maximal exercise HHb was significantly higher in the BB compared with AD (p < 0.05). Relative to the other 3 muscles, BB exhibited the greatest decrease in O2Hb and TOI (p < 0.05). Our investigation provides two new and important findings: (i) during submaximal ACE the BB, TR, BR, and AD exhibit similar changes in muscle deoxygenation and (ii) during maximal ACE the BB exhibits the greatest change in intramuscular O2 status.

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4

Chin, Lisa M. K., John M. Kowalchuk, Thomas J. Barstow, Narihiko Kondo, Tatsuro Amano, Tomoyuki Shiojiri, and Shunsaku Koga. "The relationship between muscle deoxygenation and activation in different muscles of the quadriceps during cycle ramp exercise." Journal of Applied Physiology 111, no. 5 (November 2011): 1259–65. http://dx.doi.org/10.1152/japplphysiol.01216.2010.

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Анотація:

The relationship between muscle deoxygenation and activation was examined in three different muscles of the quadriceps during cycling ramp exercise. Seven young male adults (24 ± 3 yr; mean ± SD) pedaled at 60 rpm to exhaustion, with a work rate (WR) increase of 20 W/min. Pulmonary oxygen uptake was measured breath-by-breath, while muscle deoxygenation (HHb) and activity were measured by time-resolved near-infrared spectroscopy (NIRS) and surface electromyography (EMG), respectively, at the vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM). Muscle deoxygenation was corrected for adipose tissue thickness and normalized to the amplitude of the HHb response, while EMG signals were integrated (iEMG) and normalized to the maximum iEMG determined from maximal voluntary contractions. Muscle deoxygenation and activation were then plotted as a percentage of maximal work rate (%WRmax). The HHb response for all three muscle groups was fitted by a sigmoid function, which was determined as the best fitting model. The c/d parameter for the sigmoid fit (representing the %WRmax at 50% of the total amplitude of the HHb response) was similar between VL (47 ± 12% WRmax) and VM (43 ± 11% WRmax), yet greater ( P < 0.05) for RF (65 ± 13% WRmax), demonstrating a “right shift” of the HHb response compared with VL and VM. The iEMG also showed that muscle activation of the RF muscle was lower ( P < 0.05) compared with VL and VM throughout the majority of the ramp exercise, which may explain the different HHb response in RF. Therefore, these data suggest that the sigmoid function can be used to model the HHb response in different muscles of the quadriceps; however, simultaneous measures of muscle activation are also needed for the HHb response to be properly interpreted during cycle ramp exercise.

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5

Ambrozic, Jana, Mitja Lainscak, and Matej Podbregar. "Use of Near Infrared Spectroscopy to Asses Remote Ischemic Preconditioning in Skeletal Muscle." Physiology Journal 2013 (February 21, 2013): 1–7. http://dx.doi.org/10.1155/2013/154327.

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Remote ischemic preconditioning (IPC) is a procedure during which brief periods of ischemia protect distant organ from ischemia-reperfusion injury. Appling IPC on an upper arm, this phenomenon has been demonstrated in several studies. Skeletal muscle tissue oxygenation at rest (StO2) and StO2 deoxygenation rate during vascular occlusion can be measured using near infrared spectroscopy (NIRS). We aimed to investigate the effects of remote upper arm IPC on StO2 and flow-mediated dilatation (FMD) in healthy male volunteers. In a randomized controlled crossover trial, resting StO2, StO2 deoxygenation rate, and FMD were measured on testing arm at baseline and after 60 minutes. After basal measurements IPC protocol on a contralateral arm was performed. StO2 deoxygenation rate was significantly lower after remote, the IPC cycles in comparison to deoxygenation rate at baseline (9.7±2.6 versus 7.5±2.5%, P=0.002). Comparison of deoxygenation rates showed a significant difference between the IPC and the control protocol (F=5.512, P=0.003). No differences were observed in FMD before and after remote IPC and in the control protocol. In healthy young adults, remote IPC reduces StO2 deoxygenation rate but has no significant impact on FMD. NIRS technique offers a novel approach to asses skeletal muscle adaptation in response to remote ischemic stimuli.

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6

Kime, Ryotaro, Joohee Im, Daniel Moser, Shoko Nioka, Toshihito Katsumura, and Britton Chance. "Nonuniform muscle deoxygenation in single muscle during bicycle exercise." Japanese Journal of Physical Fitness and Sports Medicine 54, no. 1 (2005): 74. http://dx.doi.org/10.7600/jspfsm.54.74.

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7

Niemeijer, Victor M., Ruud F. Spee, Thijs Schoots, Pieter F. F. Wijn, and Hareld M. C. Kemps. "Limitations of skeletal muscle oxygen delivery and utilization during moderate-intensity exercise in moderately impaired patients with chronic heart failure." American Journal of Physiology-Heart and Circulatory Physiology 311, no. 6 (December 1, 2016): H1530—H1539. http://dx.doi.org/10.1152/ajpheart.00474.2016.

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The extent and speed of transient skeletal muscle deoxygenation during exercise onset in patients with chronic heart failure (CHF) are related to impairments of local O2 delivery and utilization. This study examined the physiological background of submaximal exercise performance in 19 moderately impaired patients with CHF (Weber class A, B, and C) compared with 19 matched healthy control (HC) subjects by measuring skeletal muscle oxygenation (SmO2) changes during cycling exercise. All subjects performed two subsequent moderate-intensity 6-min exercise tests (bouts 1 and 2) with measurements of pulmonary oxygen uptake kinetics and SmO2 using near-infrared spatially resolved spectroscopy at the vastus lateralis for determination of absolute oxygenation values, amplitudes, kinetics (mean response time for onset), and deoxygenation overshoot characteristics. In CHF, deoxygenation kinetics were slower compared with HC (21.3 ± 5.3 s vs. 16.7 ± 4.4 s, P < 0.05, respectively). After priming exercise (i.e., during bout 2), deoxygenation kinetics were accelerated in CHF to values no longer different from HC (16.9 ± 4.6 s vs. 15.4 ± 4.2 s, P = 0.35). However, priming did not speed deoxygenation kinetics in CHF subjects with a deoxygenation overshoot, whereas it did reduce the incidence of the overshoot in this specific group ( P < 0.05). These results provide evidence for heterogeneity with respect to limitations of O2 delivery and utilization during moderate-intensity exercise in patients with CHF, with slowed deoxygenation kinetics indicating a predominant O2 utilization impairment and the presence of a deoxygenation overshoot, with a reduction after priming in a subgroup, indicating an initial O2 delivery to utilization mismatch.

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8

Anthierens, Agathe, Nicolas Olivier, André Thevenon, and Patrick Mucci. "Trunk Muscle Aerobic Metabolism Responses in Endurance Athletes, Combat Athletes and Untrained Men." International Journal of Sports Medicine 40, no. 07 (June 12, 2019): 434–39. http://dx.doi.org/10.1055/a-0856-7207.

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AbstractThis study investigated aerobic metabolism responses in trunk muscles during a prolonged trunk extension exercise in athletes and untrained young men. The aim was to analyze the adaptations induced by 2 types of sports: one involving intensive use of trunk muscles (i. e., judo), and one known to induce high aerobic capacity in the whole body (i. e., cycling). Eleven judokas, 10 cyclists and 9 healthy untrained young men performed trunk extension exercises on an isokinetic dynamometer. During the first session, muscle strength was assessed during maximal trunk extension. During a second session, a 5-min exercise was performed to investigate aerobic responses with regard to trunk muscles. The near infrared spectroscopy technique and a gas exchange analyzer were used continuously to evaluate mechanical efficiency, V̇O2 on-set kinetics, trunk muscle deoxygenation and blood volume. Judokas showed greater trunk strength and mechanical efficiency (p<0.05). Cyclists presented faster V̇O2 on-set kinetics (p<0.05) and greater muscle deoxygenation and blood volume compared to untrained men (p<0.001). These results suggest that practicing judo improves trunk extension efficiency whereas cycling accelerates aerobic pathways and enhances microvascular responses to trunk extension exercise. Sport practice improves aerobic metabolism responses in trunk extensor muscles differently, according to the training specificities.

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9

Okushima, Dai, David C. Poole, Harry B. Rossiter, Thomas J. Barstow, Narihiko Kondo, Etsuko Ohmae, and Shunsaku Koga. "Muscle deoxygenation in the quadriceps during ramp incremental cycling: Deep vs. superficial heterogeneity." Journal of Applied Physiology 119, no. 11 (December 1, 2015): 1313–19. http://dx.doi.org/10.1152/japplphysiol.00574.2015.

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Анотація:

Muscle deoxygenation (i.e., deoxy[Hb + Mb]) during exercise assesses the matching of oxygen delivery (Q̇o2) to oxygen utilization (V̇o2). Until now limitations in near-infrared spectroscopy (NIRS) technology did not permit discrimination of deoxy[Hb + Mb] between superficial and deep muscles. In humans, the deep quadriceps is more highly vascularized and oxidative than the superficial quadriceps. Using high-power time-resolved NIRS, we tested the hypothesis that deoxygenation of the deep quadriceps would be less than in superficial muscle during incremental cycling exercise in eight males. Pulmonary V̇o2 was measured and muscle deoxy[Hb + Mb] was determined in the superficial vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF-s) and the deep rectus femoris (RF-d). deoxy[Hb + Mb] in RF-d was significantly less than VL at 70% (67.2 ± 7.0 vs. 75.5 ± 10.7 μM) and 80% (71.4 ± 11.0 vs. 79.0 ± 15.4 μM) of peak work rate (WRpeak), but greater than VL and VM at WRpeak (87.7 ± 32.5 vs. 76.6 ± 17.5 and 75.1 ± 19.9 μM). RF-s was intermediate at WRpeak (82.6 ± 18.7 μM). Total hemoglobin and myoglobin concentration and tissue oxygen saturation were significantly greater in RF-d than RF-s throughout exercise. The slope of deoxy[Hb + Mb] increase (proportional to Q̇o2/V̇o2) in VL and VM slowed markedly above 70% WRpeak, whereas it became greater in RF-d. This divergent deoxygenation pattern may be due to a greater population of slow-twitch muscle fibers in the RF-d muscle and the differential recruitment profiles and vascular and metabolic control properties of specific fiber populations within superficial and deeper muscle regions.

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10

Goulding, Richie P., Simon Marwood, Dai Okushima, David C. Poole, Thomas J. Barstow, Tze-Huan Lei, Narihiko Kondo, and Shunsaku Koga. "Effect of priming exercise and body position on pulmonary oxygen uptake and muscle deoxygenation kinetics during cycle exercise." Journal of Applied Physiology 129, no. 4 (October 1, 2020): 810–22. http://dx.doi.org/10.1152/japplphysiol.00478.2020.

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Анотація:

Here we show that oxygen uptake (V̇o2) kinetics are slower in the supine compared with upright body position, an effect that is associated with an increased amplitude of skeletal muscle deoxygenation in the supine position. After priming in the supine position, the amplitude of muscle deoxygenation remained markedly elevated above that observed during upright exercise. Hence, the priming effect cannot be solely attributed to enhanced O2 delivery, and enhancements to intracellular O2 utilization must also be contributory.

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11

CHUANG, MING-LUNG, HUA TING, TOSHIHIRO OTSUKA, XING-GUO SUN, FRANK Y.-L. CHIU, JAMES E. HANSEN, and KARLMAN WASSERMAN. "Muscle deoxygenation as related to work rate." Medicine & Science in Sports & Exercise 34, no. 10 (October 2002): 1614–23. http://dx.doi.org/10.1097/00005768-200210000-00013.

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12

Hamaoka, T., M. Niwayama, R. Kime, D. Kohata, K. Yamamoto, and T. Katsumura. "NEAR INFRARED IMAGING OF SKELETAL MUSCLE DEOXYGENATION." Medicine & Science in Sports & Exercise 33, no. 5 (May 2001): S328. http://dx.doi.org/10.1097/00005768-200105001-01838.

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13

Koga, Shunsaku, Thomas J. Barstow, Dai Okushima, Harry B. Rossiter, Narihiko Kondo, Etsuko Ohmae, and David C. Poole. "Validation of a high-power, time-resolved, near-infrared spectroscopy system for measurement of superficial and deep muscle deoxygenation during exercise." Journal of Applied Physiology 118, no. 11 (June 1, 2015): 1435–42. http://dx.doi.org/10.1152/japplphysiol.01003.2014.

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Анотація:

Near-infrared assessment of skeletal muscle is restricted to superficial tissues due to power limitations of spectroscopic systems. We reasoned that understanding of muscle deoxygenation may be improved by simultaneously interrogating deeper tissues. To achieve this, we modified a high-power (∼8 mW), time-resolved, near-infrared spectroscopy system to increase depth penetration. Precision was first validated using a homogenous optical phantom over a range of inter-optode spacings (OS). Coefficients of variation from 10 measurements were minimal (0.5-1.9%) for absorption (μa), reduced scattering, simulated total hemoglobin, and simulated O2 saturation. Second, a dual-layer phantom was constructed to assess depth sensitivity, and the thickness of the superficial layer was varied. With a superficial layer thickness of 1, 2, 3, and 4 cm (μa = 0.149 cm−1), the proportional contribution of the deep layer (μa = 0.250 cm−1) to total μa was 80.1, 26.9, 3.7, and 0.0%, respectively (at 6-cm OS), validating penetration to ∼3 cm. Implementation of an additional superficial phantom to simulate adipose tissue further reduced depth sensitivity. Finally, superficial and deep muscle spectroscopy was performed in six participants during heavy-intensity cycle exercise. Compared with the superficial rectus femoris, peak deoxygenation of the deep rectus femoris (including the superficial intermedius in some) was not significantly different (deoxyhemoglobin and deoxymyoglobin concentration: 81.3 ± 20.8 vs. 78.3 ± 13.6 μM, P > 0.05), but deoxygenation kinetics were significantly slower (mean response time: 37 ± 10 vs. 65 ± 9 s, P ≤ 0.05). These data validate a high-power, time-resolved, near-infrared spectroscopy system with large OS for measuring the deoxygenation of deep tissues and reveal temporal and spatial disparities in muscle deoxygenation responses to exercise.

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14

Chance, B., M. T. Dait, C. Zhang, T. Hamaoka, and F. Hagerman. "Recovery from exercise-induced desaturation in the quadriceps muscles of elite competitive rowers." American Journal of Physiology-Cell Physiology 262, no. 3 (March 1, 1992): C766—C775. http://dx.doi.org/10.1152/ajpcell.1992.262.3.c766.

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A simple muscle tissue spectrophotometer is adapted to measure the recovery time (TR) for hemoglobin/myoglobin (Hb/Mb) desaturation in the capillary bed of exercising muscle, termed a deoxygenation meter. The use of the instrument for measuring the extent of deoxygenation is presented, but the use of TR avoids difficulties of quantifying Hb/Mb saturation changes. The TR reflects the balance of oxygen delivery and oxygen demand in the localized muscles of the quadriceps following work near maximum voluntary contraction (MVC) in elite male and female rowers (a total of 22) on two occasions, 1 yr apart. TR ranged from 10 to 80 s and was interpreted as a measure of the time for repayment of oxygen and energy deficits accumulated during intense exercise by tissue respiration under ADP control. The Hb/Mb resaturation times provide a noninvasive localized indication of the degree of O2 delivery stress as evoked by rowing ergometry and may provide directions for localized muscle power output improvement for particular individuals in rowing competitions.

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15

Bhambhani, Yagesh N. "Muscle Oxygenation Trends During Dynamic Exercise Measured by Near Infrared Spectroscopy." Canadian Journal of Applied Physiology 29, no. 4 (August 1, 2004): 504–23. http://dx.doi.org/10.1139/h04-033.

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Анотація:

During the last decade, NIRS has been used extensively to evaluate the changes in muscle oxygenation and blood volume during a variety of exercise modes. The important findings from this research are as follows: (a) There is a strong correlation between the lactate (ventilatory) threshold during incremental cycle exercise and the exaggerated reduction in muscle oxygenation measured by NIRS. (b) The delay in steady-state oxygen uptake during constant work rate exercise at intensities above the lactate/ventilatory threshold is closely related to changes in muscle oxygenation measured by NIRS. (c) The degree of muscle deoxygenation at the same absolute oxygen uptake is significantly lower in older persons compared younger persons; however, these changes are negated when muscle oxygenation is expressed relative to maximal oxygen uptake values. (d) There is no significant difference between the rate of biceps brachii and vastus lateralis deoxygenation during arm cranking and leg cycling exercise, respectively, in males and females. (e) Muscle deoxygenation trends recorded during short duration, high-intensity exercise such as the Wingate test indicate that there is a substantial degree of aerobic metabolism during such exercise. Recent studies that have used NIRS at multiple sites, such as brain and muscle tissue, provide useful information pertaining to the regional changes in oxygen availability in these tissues during dynamic exercise. Key words: blood volume, noninvasive measurement

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16

Koga, Shunsaku, David C. Poole, Leonard F. Ferreira, Brian J. Whipp, Narihiko Kondo, Tadashi Saitoh, Etsuko Ohmae, and Thomas J. Barstow. "Spatial heterogeneity of quadriceps muscle deoxygenation kinetics during cycle exercise." Journal of Applied Physiology 103, no. 6 (December 2007): 2049–56. http://dx.doi.org/10.1152/japplphysiol.00627.2007.

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Анотація:

To test the hypothesis that, during exercise, substantial heterogeneity of muscle hemoglobin and myoglobin deoxygenation [deoxy(Hb + Mb)] dynamics exists and to determine whether such heterogeneity is associated with the speed of pulmonary O2 uptake (pV̇o2) kinetics, we adapted multi-optical fibers near-infrared spectroscopy (NIRS) to characterize the spatial distribution of muscle deoxygenation kinetics at exercise onset. Seven subjects performed cycle exercise transitions from unloaded to moderate [<gas exchange threshold (GET)] and heavy (>GET) work rates and the relative changes in deoxy(Hb + Mb), at 10 sites in the quadriceps, were sampled by NIRS. At exercise onset, the time delays in muscle deoxy(Hb + Mb) were spatially inhomogeneous [intersite coefficient of variation (CV), 3∼56% for <GET, 2∼21% for >GET]. The primary component kinetics (time constant) of muscle deoxy(Hb + Mb) reflecting increased O2 extraction were also spatially inhomogeneous (intersite CV, 6∼48% for <GET, 7∼47% for >GET) and faster (P < 0.05) than those of phase 2 pV̇o2. However, the degree of dynamic intersite heterogeneity in muscle deoxygenation did not correlate significantly with phase 2 pV̇o2 kinetics. In conclusion, the dynamics of quadriceps microvascular oxygenation demonstrates substantial spatial heterogeneity that must arise from disparities in the relative kinetics of V̇o2 and O2 delivery increase across the regions sampled.

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17

Katayama, Keisho, Yutaka Takeuchi, Yasuhide Yoshitake, Osamu Fujita, Kohei Watanabe, Hiroshi Akima, and Koji Ishida. "Muscle Deoxygenation And Electromyographic Activity During Isolated Muscle Exercise In Hypoxia." Medicine & Science in Sports & Exercise 41 (May 2009): 241. http://dx.doi.org/10.1249/01.mss.0000355291.63363.07.

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18

McKay, Bryon R., Donald H. Paterson, and John M. Kowalchuk. "Effect of short-term high-intensity interval training vs. continuous training on O2 uptake kinetics, muscle deoxygenation, and exercise performance." Journal of Applied Physiology 107, no. 1 (July 2009): 128–38. http://dx.doi.org/10.1152/japplphysiol.90828.2008.

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Анотація:

The early time course of adaptation of pulmonary O2 uptake (V̇o2p) (reflecting muscle O2 consumption) and muscle deoxygenation kinetics (reflecting the rate of O2 extraction) were examined during high-intensity interval (HIT) and lower-intensity continuous endurance (END) training. Twelve male volunteers underwent eight sessions of either HIT (8–12 × 1-min intervals at 120% maximal O2 uptake separated by 1 min of rest) or END (90–120 min at 65% maximal O2 uptake). Subjects completed step transitions to a moderate-intensity work rate (∼90% estimated lactate threshold) on five occasions throughout training, and ramp incremental and constant-load performance tests were conducted at pre-, mid-, and posttraining periods. V̇o2p was measured breath-by-breath by mass spectrometry and volume turbine. Deoxygenation (change in deoxygenated hemoglobin concentration; Δ[HHb]) of the vastus lateralis muscle was monitored by near-infrared spectroscopy. The fundamental phase II time constants for V̇o2p (τV̇o2) and deoxygenation kinetics {effective time constant, τ′ = (time delay + τ), Δ[HHb]} during moderate-intensity exercise were estimated using nonlinear least-squares regression techniques. The τV̇o2 was reduced by ∼20% ( P < 0.05) after only two training sessions and by ∼40% ( P < 0.05) after eight training sessions (i.e., posttraining), with no differences between HIT and END. The τ′Δ[HHb] (∼20 s) did not change over the course of eight training sessions. These data suggest that faster activation of muscle O2 utilization is an early adaptive response to both HIT and lower-intensity END training. That Δ[HHb] kinetics (a measure of fractional O2 extraction) did not change despite faster V̇o2p kinetics suggests that faster kinetics of muscle O2 utilization were accompanied by adaptations in local muscle (microvascular) blood flow and O2 delivery, resulting in a similar “matching” of blood flow to O2 utilization. Thus faster kinetics of V̇o2p during the transition to moderate-intensity exercise occurs after only 2 days HIT and END training and without changes to muscle deoxygenation kinetics, suggesting concurrent adaptations to microvascular perfusion.

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19

Chin, Lisa M., Tim J. H. Chaplin, Natasha N. R. Rowling, Ryan J. Leigh, Donald H. Paterson, and John M. Kowalchuk. "Vo2 And Muscle Deoxygenation Kinetics In Moderateintensity Exercise." Medicine & Science in Sports & Exercise 37, Supplement (May 2005): S449—S450. http://dx.doi.org/10.1249/00005768-200505001-02318.

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20

Chin, Lisa M., Tim J. H. Chaplin, Natasha N. R. Rowling, Ryan J. Leigh, Donald H. Paterson, and John M. Kowalchuk. "Vo2 And Muscle Deoxygenation Kinetics In Moderateintensity Exercise." Medicine & Science in Sports & Exercise 37, Supplement (May 2005): S449???S450. http://dx.doi.org/10.1097/00005768-200505001-02318.

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21

Katayama, Keisho, Yasuhiro Suzuki, Masako Hoshikawa, Toshiyuki Ohya, Marie Oriishi, Yuka Itoh, and Koji Ishida. "Hypoxia exaggerates inspiratory accessory muscle deoxygenation during hyperpnoea." Respiratory Physiology & Neurobiology 211 (June 2015): 1–8. http://dx.doi.org/10.1016/j.resp.2015.02.005.

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22

Grassi, Bruno, Valentina Quaresima, Claudio Marconi, Marco Ferrari, and Paolo Cerretelli. "Blood lactate accumulation and muscle deoxygenation during incremental exercise." Journal of Applied Physiology 87, no. 1 (July 1, 1999): 348–55. http://dx.doi.org/10.1152/jappl.1999.87.1.348.

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Near-infrared spectroscopy (NIRS) could allow insights into controversial issues related to blood lactate concentration ([La]b) increases at submaximal workloads (w˙). We combined, on five well-trained subjects [mountain climbers; peak O2 consumption (V˙o 2peak), 51.0 ± 4.2 (SD) ml ⋅ kg−1 ⋅ min−1] performing incremental exercise on a cycle ergometer (30 W added every 4 min up to voluntary exhaustion), measurements of pulmonary gas exchange and earlobe [La]b with determinations of concentration changes of oxygenated Hb (Δ[O2Hb]) and deoxygenated Hb (Δ[HHb]) in the vastus lateralis muscle, by continuous-wave NIRS. A “point of inflection” of [La]b vs.w˙ was arbitrarily identified at the lowest [La]b value which was >0.5 mM lower than that obtained at the following w˙. Total Hb volume (Δ[O2Hb + HHb]) in the muscle region of interest increased as a function ofw˙ up to 60–65% ofV˙o 2 peak, after which it remained unchanged. The oxygenation index (Δ[O2Hb − HHb]) showed an accelerated decrease from 60– 65% ofV˙o 2 peak. In the presence of a constant total Hb volume, the observed Δ[O2Hb − HHb] decrease indicates muscle deoxygenation (i.e., mainly capillary-venular Hb desaturation). The onset of muscle deoxygenation was significantly correlated ( r 2 = 0.95; P < 0.01) with the point of inflection of [La]bvs. w˙, i.e., with the onset of blood lactate accumulation. Previous studies showed relatively constant femoral venous[Formula: see text] levels at w˙ higher than ∼60% of maximal O2consumption. Thus muscle deoxygenation observed in the present study from 60–65% ofV˙o 2 peak could be attributed to capillary-venular Hb desaturation in the presence of relatively constant capillary-venular[Formula: see text] levels, as a consequence of a rightward shift of the O2Hb dissociation curve determined by the onset of lactic acidosis.

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23

Runacres, Adam, Kelly Mackintosh, Tim Evans, and Melitta A. McNarry. "Effects of Sex, Training, and Maturity Status on the Cardiopulmonary and Muscle Deoxygenation Responses during Incremental Ramp Exercise." International Journal of Environmental Research and Public Health 19, no. 12 (June 16, 2022): 7410. http://dx.doi.org/10.3390/ijerph19127410.

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Whilst participation in regular exercise and sport has generally increased over recent decades globally, fundamental questions remain regarding the influence of growth, maturation, and sex on the magnitude of training response throughout adolescence. Trained (108 participants, 43 girls; age: 14.3 ± 1.8 years) and untrained (108 participants, 43 girls; age: 14.7 ± 1.7 years) adolescents completed an incremental ramp test to exhaustion during which breath by gas exchange, beat-by-beat heart rate (HR), stroke volume (SV) and cardiac output (Q̇) and muscle deoxygenation were assessed. Device-based physical activity was also assessed over seven consecutive days. Boys, irrespective of training status, had a significantly higher absolute (2.65 ± 0.70 L min−1 vs. 2.01 ± 0.45 L min−1, p < 0.01) and allometrically scaled (183.8 ± 31.4 mL·kg−b min−1 vs. 146.5 ± 28.5 mL·kg−b min−1, p < 0.01) peak oxygen uptake (V̇O2) than girls. There were no sex differences in peak HR, SV or Q̇ but boys had a higher muscle deoxygenation plateau when expressed against absolute work rate and V̇O2 (p < 0.05). Muscle deoxygenation appears to be more important in determining the sex differences in peak V̇O2 in youth. Future research should examine the effects of sex on the response to different training methodologies in youth.

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24

RACINAIS, S??BASTIEN, DAVID BISHOP, ROMAIN DENIS, GR??GORY LATTIER, ALBERTO MENDEZ-VILLANEUVA, and ST??PHANE PERREY. "Muscle Deoxygenation and Neural Drive to the Muscle during Repeated Sprint Cycling." Medicine & Science in Sports & Exercise 39, no. 2 (February 2007): 268–74. http://dx.doi.org/10.1249/01.mss.0000251775.46460.cb.

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25

KIME, RYOTARO, JOOHEE IM, DANIEL MOSER, YUANQING LIN, SHOKO NIOKA, TOSHIHITO KATSUMURA, and BRITTON CHANCE. "Reduced Heterogeneity of Muscle Deoxygenation during Heavy Bicycle Exercise." Medicine & Science in Sports & Exercise 37, no. 3 (March 2005): 412–17. http://dx.doi.org/10.1249/01.mss.0000155401.81284.76.

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26

LEGRAND, RENAUD, SA??D AHMAIDI, WASSIM MOALLA, DOMINIQUE CHOCQUET, ALEXANDRE MARLES, FABRICE PRIEUR, and PATRICK MUCCI. "O2 Arterial Desaturation in Endurance Athletes Increases Muscle Deoxygenation." Medicine & Science in Sports & Exercise 37, no. 5 (May 2005): 782–88. http://dx.doi.org/10.1249/01.mss.0000161806.47058.40.

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27

Quaresima, V., B. Grassi, C. Marconi, M. Ferrari, and P. Cerretelli. "BLOOD LACTATE ACCUMULATION IS ASSOCIATED WITH ACCELERATED MUSCLE DEOXYGENATION." Medicine & Science in Sports & Exercise 30, Supplement (May 1998): 67. http://dx.doi.org/10.1097/00005768-199805001-00381.

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28

Takagi, Shun, Norio Murase, Ryotaro Kime, Masatsugu Niwayama, Takuya Osada, and Toshihito Katsumura. "Skeletal Muscle Deoxygenation Abnormalities in Early Post-Myocardial Infarction." Medicine & Science in Sports & Exercise 46, no. 11 (November 2014): 2062–69. http://dx.doi.org/10.1249/mss.0000000000000334.

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29

Snyder, Ann C., Robert W. Wilson, and Jason C. Dorman. "Muscle Deoxygenation and Power Output during Triple Wingate Tests." Medicine & Science in Sports & Exercise 38, Supplement (May 2006): S514. http://dx.doi.org/10.1249/00005768-200605001-03021.

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30

Kahn, J. F., J. C. Jouanin, J. L. Bussi�re, E. Tinet, S. Avrillier, J. P. Ollivier, and H. Monod. "The isometric force that induces maximal surface muscle deoxygenation." European Journal of Applied Physiology 78, no. 2 (June 1, 1998): 183–87. http://dx.doi.org/10.1007/s004210050405.

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31

Okushima, Dai, David C. Poole, Thomas J. Barstow, Narihiko Kondo, Lisa M. K. Chin, and Shunsaku Koga. "Effect of differential muscle activation patterns on muscle deoxygenation and microvascular haemoglobin regulation." Experimental Physiology 105, no. 3 (February 9, 2020): 531–41. http://dx.doi.org/10.1113/ep088322.

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32

Cheng, Ching-Feng, Tomas K. Tong, Yu-Chi Kuo, Pin-Hui Chen, Hsin-Wei Huang, and Chia-Lun Lee. "Inspiratory muscle warm-up attenuates muscle deoxygenation during cycling exercise in women athletes." Respiratory Physiology & Neurobiology 186, no. 3 (May 2013): 296–302. http://dx.doi.org/10.1016/j.resp.2013.02.029.

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33

Gildea, Norita, Adam McDermott, Joel Rocha, Donal O’Shea, Simon Green, and Mikel Egaña. "Time-course of V̇o2 kinetics responses during moderate-intensity exercise subsequent to HIIT versus moderate-intensity continuous training in type 2 diabetes." Journal of Applied Physiology 130, no. 6 (June 1, 2021): 1646–59. http://dx.doi.org/10.1152/japplphysiol.00952.2020.

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High-intensity interval training and moderate-intensity continuous training elicited faster pulmonary oxygen uptake (V̇o2) kinetics during moderate-intensity cycling within 3 wk of training with no further changes thereafter in individuals with type 2 diabetes. These adaptations were accompanied by unaltered near-infrared spectroscopy-derived muscle deoxygenation (i.e. deoxygenated hemoglobin and myoglobin concentration, [HHb+Mb]) kinetics and transiently reduced Δ[HHb+Mb]-to-ΔV̇o2 ratio, suggesting an enhanced blood flow distribution within the active muscles subsequent to both training interventions.

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34

Contreras-Briceño, Felipe, Maximiliano Espinosa-Ramírez, Eduardo Moya-Gallardo, Rodrigo Fuentes-Kloss, Luigi Gabrielli, Oscar F. Araneda, and Ginés Viscor. "Intercostal Muscles Oxygenation and Breathing Pattern during Exercise in Competitive Marathon Runners." International Journal of Environmental Research and Public Health 18, no. 16 (August 5, 2021): 8287. http://dx.doi.org/10.3390/ijerph18168287.

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The study aimed to evaluate the association between the changes in ventilatory variables (tidal volume (Vt), respiratory rate (RR) and lung ventilation (V.E)) and deoxygenation of m.intescostales (∆SmO2-m.intercostales) during a maximal incremental exercise in 19 male high-level competitive marathon runners. The ventilatory variables and oxygen consumption (V.O2) were recorded breath-by-breath by exhaled gas analysis. A near-infrared spectroscopy device (MOXY®) located in the right-hemithorax allowed the recording of SmO2-m.intercostales. To explore changes in oxygen levels in muscles with high demand during exercise, a second MOXY® records SmO2-m.vastus laterallis. The triphasic model of exercise intensity was used for evaluating changes in SmO2 in both muscle groups. We found that ∆SmO2-m.intercostales correlated with V.O2-peak (r = 0.65; p = 0.002) and the increase of V.E (r = 0.78; p = 0.001), RR (r = 0.54; p = 0.001), but not Vt (p = 0.210). The interaction of factors (muscles × exercise-phases) in SmO2 expressed as an arbitrary unit (a.u) was significant (p = 0.005). At VT1 there was no difference (p = 0.177), but SmO2-m.intercostales was higher at VT2 (p < 0.001) and V.O2-peak (p < 0.001). In high-level competitive marathon runners, the m.intercostales deoxygenation during incremental exercise is directly associated with the aerobic capacity and increased lung ventilation and respiratory rate, but not tidal volume. Moreover, it shows less deoxygenation than m.vastus laterallis at intensities above the aerobic ventilatory threshold.

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35

Uchiyama, Keita, Hiroichi Miaki, Shigeru Terada, and Masahiro Hoso. "Effect of Muscle Strength Training and Muscle Endurance Training on Muscle Deoxygenation Level and Endurance Performance." Journal of Physical Therapy Science 23, no. 2 (2011): 349–55. http://dx.doi.org/10.1589/jpts.23.349.

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36

Zorgati, Houssem, Katia Collomp, Virgile Amiot, and Fabrice Prieur. "Effect of pedal cadence on the heterogeneity of muscle deoxygenation during moderate exercise." Applied Physiology, Nutrition, and Metabolism 38, no. 12 (December 2013): 1206–10. http://dx.doi.org/10.1139/apnm-2012-0504.

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This study examined the effect of pedal cadence on the heterogeneity of muscle deoxygenation during exercise of moderate intensity. Twelve healthy subjects performed 6 min of cycling at 40 and 100 r·min–1 at 80% of the workload corresponding to the gas exchange threshold. Gas exchanges were measured breath by breath during each exercise. Muscle deoxygenation (HHb, i.e., O2 extraction) was monitored continuously by near-infrared spectroscopy at eight sites on the vastus lateralis. The heterogeneity of HHb was assessed using the relative dispersion of the signal measured at the eight sites (i.e., 100 × standard deviation / mean). HHb was not altered by the pedal cadence, whereas pulmonary V̇O2 was higher at 100 r·min–1 than at 40 r·min–1 (p < 0.001). The relative dispersion of HHb was significantly higher at 100 r·min–1 than at 40 r·min–1 (p < 0.001). These results indicate that pedal cadence has no effect on O2 extraction but that an elevated cadence would increase muscle V̇O2, suggesting an increase in muscle blood flow. Elevated cadence also induced greater heterogeneity of the muscle’s V̇O2/Q̇O2 delivery ratio, suggesting a change in the adequacy between O2 demand and O2 delivery in some regions of active muscle.

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37

DeLorey, D. S., J. M. Kowalchuk, and D. H. Paterson. "THE RELATIONSHIP BETWEEN PULMONARY O2 UPTAKE KINETICS AND MUSCLE DEOXYGENATION." Medicine & Science in Sports & Exercise 34, no. 5 (May 2002): S110. http://dx.doi.org/10.1097/00005768-200205001-00617.

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38

Murias, Juan M., Daniel A. Keir, Matthew D. Spencer, and Donald H. Paterson. "Sex-related differences in muscle deoxygenation during ramp incremental exercise." Respiratory Physiology & Neurobiology 189, no. 3 (December 2013): 530–36. http://dx.doi.org/10.1016/j.resp.2013.08.011.

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39

Vogiatzis, I., D. Athanasopoulos, G. Stratakos, C. Garagouni, A. Koutsoukou, R. Boushel, C. Roussos, and S. Zakynthinos. "Exercise-induced skeletal muscle deoxygenation in O2-supplemented COPD patients." Scandinavian Journal of Medicine & Science in Sports 19, no. 3 (June 2009): 364–72. http://dx.doi.org/10.1111/j.1600-0838.2008.00808.x.

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40

Takagi, Shun, Norio Murase, Ryotaro Kime, Masatsugu Niwayama, Takuya Osada, and Toshihito Katsumura. "Aerobic training enhances muscle deoxygenation in early post-myocardial infarction." European Journal of Applied Physiology 116, no. 4 (January 12, 2016): 673–85. http://dx.doi.org/10.1007/s00421-016-3326-x.

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41

Leclair, Erwan, Delphine Thevenet, Sophie C. Reguem, Benoit Borel, Georges Baquet, Serge Berthoin, and Patrick Mucci. "Reproducibility of Measurement of Muscle Deoxygenation in Children During Exercise." Pediatric Exercise Science 22, no. 2 (May 2010): 183–94. http://dx.doi.org/10.1123/pes.22.2.183.

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This study was designed to test the reproducibility of muscle oxygenation by NIRS in children during exercise. Twelve healthy non-obese and non-trained children performed one maximal graded test, and four 6-min constant load cycle exercises. Deoxy-hemoglobin (Hb/Mb-H+) data were averaged every 1, 5, 10, 20 and 30s. Hb/Mb-H+ data averaged every 5, 10, 20 and 30s showed good reproducibility. When averaged every second, Hb/Mb-H+ values were reproducible after the first minute of exercise. Based on 1s averaged signal modeling, time period and t values for Hb/Mb-H+ were not reproducible but mean response time values showed an acceptable reproducibility.

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42

KATAYAMA, KEISHO, YASUHIDE YOSHITAKE, KOHEI WATANABE, HIROSHI AKIMA, and KOJI ISHIDA. "Muscle Deoxygenation during Sustained and Intermittent Isometric Exercise in Hypoxia." Medicine & Science in Sports & Exercise 42, no. 7 (July 2010): 1269–78. http://dx.doi.org/10.1249/mss.0b013e3181cae12f.

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43

Caldwell, Jacob T., Garrett C. Wardlow, Patrece A. Branch, Macarena Ramos, Christopher D. Black, and Carl J. Ade. "Effect of exercise-induced muscle damage on vascular function and skeletal muscle microvascular deoxygenation." Physiological Reports 4, no. 22 (November 2016): e13032. http://dx.doi.org/10.14814/phy2.13032.

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44

Gurd, Brendon J., Sandra J. Peters, George J. F. Heigenhauser, Paul J. LeBlanc, Timothy J. Doherty, Donald H. Paterson, and John M. Kowalchuk. "Prior heavy exercise elevates pyruvate dehydrogenase activity and muscle oxygenation and speeds O2 uptake kinetics during moderate exercise in older adults." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 297, no. 3 (September 2009): R877—R884. http://dx.doi.org/10.1152/ajpregu.90848.2008.

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The adaptation of pulmonary oxygen uptake (V̇o2p) kinetics during the transition to moderate-intensity exercise is slowed in older compared with younger adults; however, this response is faster following a prior bout of heavy-intensity exercise. We have examined V̇o2p kinetics, pyruvate dehydrogenase (PDH) activation, muscle metabolite contents, and muscle deoxygenation in older adults [ n = 6; 70 ± 5 (67–74) yr] during moderate-intensity exercise (Mod1) and during moderate-intensity exercise preceded by heavy-intensity warm-up exercise (Mod2). The phase 2 V̇o2p time constant (τV̇o2p) was reduced ( P < 0.05) in Mod2 (29 ± 5 s) compared with Mod1 (39 ± 14 s). PDH activity was elevated ( P < 0.05) at baseline prior to Mod2 (2.1 ± 0.6 vs. 1.2 ± 0.3 mmol acetyl-CoA·min−1·kg wet wt−1), and the delay in attaining end-exercise activity was abolished. Phosphocreatine breakdown during exercise was reduced ( P < 0.05) at both 30 s and 6 min in Mod2 compared with Mod1. Near-infrared spectroscopy-derived indices of muscle oxygenation were elevated both prior to and throughout Mod2, while muscle deoxygenation kinetics were not different between exercise bouts consistent with elevated perfusion and O2 availability. These results suggest that in older adults, faster V̇o2p kinetics following prior heavy-intensity exercise are likely a result of prior activation of mitochondrial enzyme activity in combination with elevated muscle perfusion and O2 availability.

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45

Wang, Lixin, Takahiro Yoshikawa, Taketaka Hara, Hayato Nakao, Takashi Suzuki, and Shigeo Fujimoto. "Which common NIRS variable reflects muscle estimated lactate threshold most closely?" Applied Physiology, Nutrition, and Metabolism 31, no. 5 (October 2006): 612–20. http://dx.doi.org/10.1139/h06-069.

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Various near-infrared spectroscopy (NIRS) variables have been used to estimate muscle lactate threshold (LT), but no study has determined which common NIRS variable best reflects muscle estimated LT. Establishing the inflection point of 2 regression lines for deoxyhaemoglobin (ΔHHbi.p.), oxyhaemoglobin (ΔO2Hbi.p.), and tissue oxygenation index (TOIi.p.), as well as for blood lactate concentration, we then investigated the relationships between NIRS variables and ventilatory threshold (VT), LT, or maximal tissue hemoglobin index (nTHImax) during incremental cycling exercise. ΔHHbi.p. and TOIi.p. could be determined for all 15 subjects, but ΔO2Hbi.p. was determined for only 11 subjects. The mean absolute values for the 2 measurable slopes of the 2 continuous linear regression lines exhibited increased changes in 3 NIRS variables. The workload and VO2 at ΔO2Hbi.p. and nTHImax were greater than those at VT, LT, ΔHHbi.p., and TOIi.p.. For workload and VO2, ΔHHbi.p. was correlated with VT and LT, whereas ΔO2Hbi.p. was correlated with nTHImax, and TOIi.p. with VT and nTHImax. These findings indicate that ΔO2Hb strongly corresponds with local perfusion, and TOI corresponds with both local perfusion and deoxygenation, but that ΔHHb can exactly determine deoxygenation changes and reflect O2 metabolic dynamics. The finding of strongest correlations between ΔHHb and VT or LT indicates that ΔHHb is the best variable for muscle LT estimation.

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46

Koga, Shunsaku, David C. Poole, Yoshiyuki Fukuoka, Leonardo F. Ferreira, Narihiko Kondo, Etsuko Ohmae, and Thomas J. Barstow. "Methodological validation of the dynamic heterogeneity of muscle deoxygenation within the quadriceps during cycle exercise." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 301, no. 2 (August 2011): R534—R541. http://dx.doi.org/10.1152/ajpregu.00101.2011.

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The conventional continuous wave near-infrared spectroscopy (CW-NIRS) has enabled identification of regional differences in muscle deoxygenation following onset of exercise. However, assumptions of constant optical factors (e.g., path length) used to convert the relative changes in CW-NIRS signal intensity to values of relative concentration, bring the validity of such measurements into question. Furthermore, to justify comparisons among sites and subjects, it is essential to correct the amplitude of deoxygenated hemoglobin plus myoglobin [deoxy(Hb+Mb)] for the adipose tissue thickness (ATT). We used two time-resolved NIRS systems to measure the distribution of the optical factors directly, thereby enabling the determination of the absolute concentrations of deoxy(Hb+Mb) simultaneously at the distal and proximal sites within the vastus lateralis (VL) and the rectus femoris muscles. Eight subjects performed cycle exercise transitions from unloaded to heavy work rates (>gas exchange threshold). Following exercise onset, the ATT-corrected amplitudes (Ap), time delay (TDp), and time constant (τp) of the primary component kinetics in muscle deoxy(Hb + Mb) were spatially heterogeneous (intersite coefficient of variation range for the subjects: 10–50 for Ap, 16–58 for TDp, 14–108% for τp). The absolute and relative amplitudes of the deoxy(Hb+Mb) responses were highly dependent on ATT, both within subjects and between measurement sites. The present results suggest that regional heterogeneity in the magnitude and temporal profile of muscle deoxygenation is a consequence of differential matching of O2 delivery and O2 utilization, not an artifact caused by changes in optical properties of the tissue during exercise or variability in the overlying adipose tissue.

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47

DeLorey, Darren S., John M. Kowalchuk, and Donald H. Paterson. "Relationship between pulmonary O2 uptake kinetics and muscle deoxygenation during moderate-intensity exercise." Journal of Applied Physiology 95, no. 1 (July 2003): 113–20. http://dx.doi.org/10.1152/japplphysiol.00956.2002.

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The temporal relationship between the kinetics of phase 2 pulmonary O2 uptake (V̇o2p) and deoxygenation of the vastus lateralis muscle was examined during moderate-intensity leg-cycling exercise. Young adults (5 men, 6 women; 23 ± 3 yr; mean ± SD) performed repeated transitions on 3 separate days from 20 W to a constant work rate corresponding to 80% of lactate threshold. Breath-by-breath V̇o2p was measured by mass spectrometer and volume turbine. Deoxyhemoglobin (HHb), oxyhemoglobin, and total hemoglobin and myoglobin were sampled each second by near-infrared spectroscopy (Hamamatsu NIRO-300). V̇o2p data were filtered, interpolated to 1 s, and averaged to 5-s bins; HHb data were averaged to 5-s bins. Phase 2 V̇o2p data were fit with a monoexponential model. For HHb, a time delay (TDHHb) from exercise onset to an increase in HHb was determined, and thereafter data were fit with a monoexponential model. The time constant for V̇o2p (30 ± 8 s) was slower ( P < 0.01) than that for HHb (10 ± 3 s). The TDHHb before an increase in HHb was 13 ± 2 s. The possible mechanisms of the TDHHb are discussed with reference to metabolic activation and matching of local muscle O2 delivery and O2 utilization. After this initial TDHHb, the kinetics of local muscle deoxygenation were faster than those of phase 2 V̇o2p (and presumably muscle O2 consumption), reflecting increased O2 extraction and a mismatch between local muscle O2 consumption and perfusion.

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48

Alharbi, Ahad Abdulkarim D., Noriaki Iwamoto, Naoyuki Ebine, Satoshi Nakae, Tatsuya Hojo, and Yoshiyuki Fukuoka. "The Acute Effects of a Single Dose of Molecular Hydrogen Supplements on Responses to Ergogenic Adjustments during High-Intensity Intermittent Exercise in Humans." Nutrients 14, no. 19 (September 24, 2022): 3974. http://dx.doi.org/10.3390/nu14193974.

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This research examined the effects of single-dose molecular hydrogen (H2) supplements on acid-base status and local muscle deoxygenation during rest, high-intensity intermittent training (HIIT) performance, and recovery. Ten healthy, trained subjects in a randomized, double-blind, crossover design received H2-rich calcium powder (HCP) (1500 mg, containing 2.544 μg of H2) or H2-depleted placebo (1500 mg) supplements 1 h pre-exercise. They performed six bouts of 7 s all-out pedaling (HIIT) at 7.5% of body weight separated by 40 s pedaling intervals, followed by a recovery period. Blood gases’ pH, PCO2, and HCO3− concentrations were measured at rest. Muscle deoxygenation (deoxy[Hb + Mb]) and tissue O2 saturation (StO2) were determined via time-resolved near-infrared spectroscopy in the vastus lateralis (VL) and rectus femoris (RF) muscles from rest to recovery. At rest, the HCP group had significantly higher PCO2 and HCO3− concentrations and a slight tendency toward acidosis. During exercise, the first HIIT bout’s peak power was significantly higher in HCP (839 ± 112 W) vs. Placebo (816 ± 108 W, p = 0.001), and HCP had a notable effect on significantly increased deoxy[Hb + Mb] concentration during HIIT exercise, despite no differences in heart rate response. The HCP group showed significantly greater O2 extraction in VL and microvascular (Hb) volume in RF during HIIT exercise. The HIIT exercise provided significantly improved blood flow and muscle reoxygenation rates in both the RF and VL during passive recovery compared to rest in all groups. The HCP supplement might exert ergogenic effects on high-intensity exercise and prove advantageous for improving anaerobic HIIT exercise performance.

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49

Niemeijer, Victor M., Tim Snijders, Lex B. Verdijk, Janneau van Kranenburg, Bart B. L. Groen, Andrew M. Holwerda, Ruud F. Spee, Pieter F. F. Wijn, Luc J. C. van Loon, and Hareld M. C. Kemps. "Skeletal muscle fiber characteristics in patients with chronic heart failure: impact of disease severity and relation with muscle oxygenation during exercise." Journal of Applied Physiology 125, no. 4 (October 1, 2018): 1266–76. http://dx.doi.org/10.1152/japplphysiol.00057.2018.

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Skeletal muscle function in patients with heart failure and reduced ejection fraction (HFrEF) greatly determines exercise capacity. However, reports on skeletal muscle fiber dimensions, fiber capillarization, and their physiological importance are inconsistent. Twenty-five moderately impaired patients with HFrEF and 25 healthy control (HC) subjects underwent muscle biopsy sampling. Type I and type II muscle fiber characteristics were determined by immunohistochemistry. In patients with HFrEF, enzymatic oxidative capacity was assessed, and pulmonary oxygen uptake (V̇o2) and skeletal muscle oxygenation during maximal and moderate-intensity exercise were measured using near-infrared spectroscopy. While muscle fiber cross-sectional area (CSA) was not different between patients with HFrEF and HC, the percentage of type I fibers was higher in HC (46 ± 15 vs. 37 ± 12%, respectively, P = 0.041). Fiber type distribution and CSA were not different between patients in New York Heart Association (NYHA) class II and III. Type I muscle fiber capillarization was higher in HFrEF compared with HC[capillary-to-fiber perimeter exchange (CFPE) index: 5.70 ± 0.92 vs. 5.05 ± 0.82, respectively, P = 0.027]. Patients in NYHA class III had slower V̇o2 and muscle deoxygenation kinetics during onset of exercise and lower muscle oxidative capacity than those in class II ( P < 0.05). Also, fiber capillarization was lower but not compared with HC. Higher CFPE index was related to faster deoxygenation ( rspearman = −0.682, P = 0.001), however, not to muscle oxidative capacity ( r = −0.282, P = 0.216). Type I muscle fiber capillarization is higher in HFrEF compared with HC but not in patients with greater exercise impairment. Greater capillarization may positively affect V̇o2 kinetics by enhancing muscle oxygen diffusion. NEW & NOTEWORTHY The skeletal myopathy of chronic heart failure (HF) includes a greater percentage of fatigable type II fibers and, for less impaired patients, greater skeletal muscle fiber capillarization. Near-infrared spectroscopy measurements of skeletal muscle oxygenation indicate that greater capillarization may compensate for reduced blood flow in mild HF by enhancing the diffusive capacity of skeletal muscle. This thereby augments and speeds oxygen extraction during contractions, which is translated into faster pulmonary oxygen uptake kinetics.

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Hamaoka, Takafumi, Toshihito Katsumura, Norio Murase, Shinya Nishio, Takuya Osada, Takayuki Sako, Hiroyuki Higuchi, et al. "Quantification of ischemic muscle deoxygenation by near infrared time-resolved spectroscopy." Journal of Biomedical Optics 5, no. 1 (2000): 102. http://dx.doi.org/10.1117/1.429975.

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