Dissertations / Theses: 'High intensity exercise'

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Rognmo, Øivind. "High-intensity aerobic exercise and cardiovascular health." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for sirkulasjon og bildediagnostikk, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-5289.

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Regelmessig fysisk aktivitet bedrer den fysiske formen, og er dokumentert å være en viktig bidragsyter med tanke på å redusere forekomsten av sykdom og dødelighet. Det maksimale oksygenopptaket, som er det beste målet på arbeidskapasitet, er vist å være en svært sterk indikator på dødelighet både hos friske og hos pasienter med hjerte-karsykdom. Regelmessig utholdenhetstrening for å øke maksimalt oksygenopptak er derfor anbefalt for bedret helse og økt livslengde. Selv om dette er etablert kunnskap, vet man lite om hvilken intensitet kondisjonstreningen bør gjennomføres med for å oppnå best mulig helsegevinst. Hensikten med denne doktorgradsavhandlingen var derfor å kartlegge hvilken intensitet i kondisjonstreningen som gir best effekt med tanke på å øke det maksimale oksygenopptaket blant pasienter med koronarsykdom. Vi ønsket også å studere hvorvidt intensiteten er viktig for å bedre fysisk form og redusere risikofaktorer for hjerte-karsykdom hos pasienter med metabolsk syndrom, som har en sterk opphopning av disse risikofaktorene. Derfor sammenliknet vi aerob intervalltrening med høy intensitet (80-90 % av maksimalt oksygenopptak) med kontinuerlig kondisjonstrening med moderat intensitet (50-60 % av maksimalt oksygenopptak) der total treningsmengde var lik. Videre ønsket vi å undersøke hvordan blodårenes funksjon og elastisitet ble påvirket av ulik type trening, både blant unge trente og utrente, og blant pasienter med metabolsk syndrom. Resultatene viste at trening med høy intensitet ga bedre effekter enn moderat intensitet for å bedre aerob kapasitet og redusere kjente risikofaktorer forbundet med hjerte-karsykdom, inkludert blodårefunksjonen. Avhandlingen kan derfor bidra med ny innsikt med tanke på bruk av aerob intervalltrening for mer effektivt å bedre kondisjonen og dermed helsen, både blant hjertesyke og hos individer med forhøyet risiko for fremtidig hjerte-karsykdom

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Lakomy, Henryk K. A. "Measurement of external power output during high intensity exercise." Thesis, Loughborough University, 1988. https://dspace.lboro.ac.uk/2134/7511.

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James, Oliver. "The effect of self-regulation on high intensity exercise." Thesis, Abertay University, 2018. https://rke.abertay.ac.uk/en/studentTheses/64d88b8e-7b66-47ec-a99a-f20a5aa92a08.

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The overall aim to this thesis was to identify if the use of self-regulated (SR) rest during high intensity training (HIT) can be used to increase endurance and power output measures between males and females. Study one aimed to determine if males and females can maintain mean power output (MPO) during repeated sprints when using self-regulated (SR) rest, and identify male and female response in MPO when SR rest is reduced. Participants completed four trials of 10 x 6 sec sprints separated by SR rest against 7.5% body mass (BM) as a resistance. If the mean power output (MPO) for all ten sprints in each trial had a coefficient of variation (CV) of ≤ 5.2%, then it was deemed that the participant was able to maintain their MPO. In trials 1-4 males significantly maintained their MPO greater than females in relation to their respected criterion sprint MPO data. In addition to this, only 85% of the participants could maintain their MPO when using SR rest (two males and one female failed). When SR rest was reduced by 10 and 15% there was no difference in CV between these two trials and the original 4 trials. However, MPO significantly dropped greater in females than in males SR rest was reduced by 15%. Therefore, this study indicates that males can use SR rest to maintain their MPO greater than females, and participants may be pacing their sprint efforts to maintain a sub-maximal MPO instead of their maximal MPO when SR rest is reduced by 15%. Study two aimed to compare endurance and Wingate power output adaptations to HIT with a fixed rest (30 sec) or self-regulated rest, and identify if reproducibility of MPO during HIT is correlated to endurance and Wingate power output adaptation. Male participants the same HIT protocol from Study 1 for six sessions over a two-week period. Participants completed the HIT with either SR rest or with a fixed rest (FR) of 30 sec between each sprint. Magnitude in change for time to exhaustion (TTE), time trial (TT) and Wingate power measures was greater in the SR group, whereas VO2 peak increased greater in the FR group. However, no strong correlation between maintaining power output and increasing endurance measures or power measures appeared. Whereas correlation data indicates that VO2 peak increased for the FR group due to a decrease in power output during the trials. Therefore, this study indicates that TTE, TT and Wingate power output experience a greater increase when rest is SR and with the aim of maintaining MPO during HIT. Study three aimed to compare the magnitude in change in VO2 peak, TTE, TT, and critical power (CP) when SR rest is reduced by 15 and 20% during HIT between males and females. Participants completed the same HIT protocol from the previous studies but completed eight HIT sessions over a four week period. Both training groups experienced a significant increase in endurance performance as measured via VO2 peak (males only), TTE, TT and critical power (20% group only). A larger aerobic response during the HIT was significantly correlated to an increase in VO2 peak in both males and females. Increases in critical power was significantly correlated to an improved TT time, which was also significantly correlated to increasing TTE. Indicating that TTE and TT improved due to an increase in greater power output. Reducing SR rest leads to a greater increase in endurance measures compared to non-reduced SR rest (Study 2), apart from females VO2 peak who saw no change. Conclusion: Overall this thesis can conclude that: 1) males appear to maintain their MPO greater than females when using SR rest and females experience a greater drop in trial MPO when SR rest is reduced. 2) Participants may be pacing in trials as CV remains unchanged but MPO decreases. 3) The CV method to identify successful SR rest to maintain MPO is unreliable and doesn’t take into account potential pacing tactics. 4). SR rest in HIT causes a greater increase in TTE, TT and Wingate power output measures, however, using a FR leads to greater increases in VO2 peak all in males. 5) Reduced SR rest causes a greater increase in TTE, TT and VO2 peak (males only) compared to SR rest, and also increases CP. 6) Maintaining MPO during HIT is not strongly correlated to increasing endurance or power output measures.

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Kaus, Reed J. "Affect and Enjoyment Associated with CrossFit Exercise." Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1395427844.

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Dolan, Lianne Bronagh. "High-intensity exercise and safety concerns in breast cancer survivors." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44196.

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Marlin, D. J. "Metabolic response to high-intensity exercise in the thoroughbred horse." Thesis, Loughborough University, 1989. https://dspace.lboro.ac.uk/2134/7870.

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The Thoroughbred racehorse is capable of maintaining speeds of approximately 17 m/s for distances of over a mile. This represents an average speed and the Thoroughbred can reach speeds in excess of 20 m/s over short distances. The present series of studies was undertaken to investigate further the metabolic response to high-intensity exercise in the Thoroughbred racehorse. Unlike man, high-intensity exercise in the horse results in an increase in packed cell volume. This in turn causes acute changes in the colligative properties of blood and plasma. The changes in these properties were investigated and the effect on calculation and distribution of metabolites in blood and muscle was determined. The horse has a high capacity for lactate production compared to man and existing methodology for the assessment of muscle buffering capacity in biopsy samples was further developed and investigated. The horse was found to have a significantly higher muscle buffering capacity compared with man and it was calculated that this could be explained wholly on the basis of the higher muscle carnosine content in the horse. The metabolic response to high-intensity exercise was investigated using several exercise models, including single and multiple field gallops and treadmill exercise. A consistent finding was that high-intensity exercise in the Thoroughbred racehorse was nearly always accompanied by a reduction in muscle ATP content. The nature of the ATP decrease was further investigated using a treadmill exercise model. Muscle ATP decrease was found to occur at a particular exercise intensity rather than show a gradual decrease with increasing intensity. The intensity at which muscle ATP content began to decline significantly varied between individual horses, but in each case appeared to coincide with muscle lactate contents of approximately 70 mmol/kg dry muscle. The significance of the decline in ATP is discussed.

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Doherty, Michael. "The effects of caffeine on short-term, high-intensity exercise." Thesis, University of Bedfordshire, 2004. http://hdl.handle.net/10547/292660.

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The aim of this series of studies was to investigate the effects of oral caffeine ingestion (5 mg . kg-1) on whole-body, short-term, high-intensity exercise (ST; representing an exercise intensity of between 100% -150% V02 max), an area that has received scant attention in the past. It was found that, in common with other 'open-ended' tests, one ST assessment, the maximal accumulated oxygen deficit (MAOD), appeared to lack both validity and reliability. Although traditional reliability markers of MAOD were favourable, the 95% limits of agreement were unacceptably large. In addition, the validity of MAOD was also found to be questionable because a study of elite runners revealed that a large proportion were unable to accomplish a plateau in the V02 -exercise intensity relationship. A follow-up study developed an original bespoke 'preloaded' ST cycling protocol that combined constant-rate exercise with an 'all-out' effort. This protocol appears to have several features that make it a more appropriate assessment to use in ergogenic studies than the MAOD. The work also considered the original, and as yet, undeveloped potential, for the assessment of rating of perceived exertion (RPE) during ST. It was shown for the first time that RPE (Borg scale; 6-20) could be used reliably during constant-rate ST. Three of the ten studies demonstrated that caffeine can be ergogenic during ST, with improvements averaging 11 % (95% GI, 7.4% -14.5%) above placebo treatment. In addition, the caffeine studies contributed to a meta-analysis of the effects of caffeine on test outcome that resulted in an effect size greater than zero, with 95% confidence intervals not crossing zero. The studies have examined potential physiological and metabolic mechanisms of action that may help explain caffeine's impact on ST. These suggest that there is some evidence that caffeine both stimulates anaerobic glycolysis and reduces electrolyte disturbance during ST. Finally this work has demonstrated for the first time that the perceptual response during constant-rate ST, as measured by RPE, is blunted following caffeine ingestion. It is concluded that caffeine is ergogenic during ST, and that while the exact mechanism(s) of action remains unknown, one consistent test outcome is a reduction in RPE during constant-rate ST.

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Hough, John. "Intensified training and salivary hormone response to high-intensity exercise." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/9887.

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Cortisol (C) and testosterone (T) are commonly suggested as markers of overreaching and the unexplained underperformance syndrome (UPS) as taken together they highlight the body s state of stress by indicating the body s catabolic/anabolic balance. Research in this area has focused on the resting concentrations of these hormones and provided inconsistent findings with increases, decreases and no changes reported when individuals are compared in an overreached state with a normally trained state. Little attention has been given to the exercise-induced responses of these hormones and whether this could be a reliable marker of overreaching/UPS. Overreaching will only occur with an intensification of training so the aims of the studies in this thesis were to determine the effects of intensified training on the exercise-induced responses of salivary and plasma C and T concentrations. Study 1 (Chapter 4) determined the salivary and plasma C, T and plasma adrenocorticotrophic hormone (ACTH) concentration responses in physically fit, healthy males to a double-bout cycle to fatigue protocol devised by Meeusen et al. (2004). They reported blunted exercise-induced hormonal responses to this protocol when well-trained cyclists were overreached compared with a normally trained state. Study 1 concluded that the exercise-induced responses of the salivary and plasma C and plasma ACTH concentrations were unaffected by a 4-day intensified training period. Blunted exercise-induced salivary and plasma T concentrations were found post-training but were due to blunted resting, basal T concentrations post-training compared with pre-training. The double-bout cycle to fatigue protocol did not elicit large C or T responses and so was not ideally suited to highlight alterations in the exercise-induced hormone responses. A high-intensity, short-duration exercise protocol (called the 55/80 bout) was established in Chapter 5 which induced robust elevations of salivary and plasma C and salivary T concentrations when in a normal trained state. Such a protocol could highlight any adaptations in the exercise-induced responses of C and T concentrations. It was also concluded that salivary and plasma C concentrations positively correlated if the peak post-exercise values were compared but not so with the salivary and plasma T concentrations. Chapter 6 and Chapter 7 concluded that blunted responses of the salivary C (Chapter 6) and T (Chapter 6 and Chapter 7) concentrations to a 55/80 bout occurred after an intensified endurance training period (~10 days). These results indicate that the 55/80 bout could be a useful detection tool of exercise-induced alterations in salivary C and T concentrations caused by an elevation of training loads in both recreationally active and elite athlete populations. The reproducibility of the salivary hormonal responses to the 55/80 bout needed to be established before it could be concluded that this was indeed a useful tool. Chapter 8 concluded that the responses of both salivary C and T concentrations to the 55/80 bout were reasonably reproducible with intra-individual variations of 12% (salivary C) and 7% (salivary T) reported. Chapter 8 also concluded that a familiarisation 55/80 bout was needed to reduce the variation in the responses of both salivary C and T concentrations. The final experimental chapter examined the response of salivary C and T over a competitive season in elite male triathletes and concluded that the 55/80 bout was unable to highlight any adaptations in the salivary C and T exercise-induced responses. This was suggested to be due to the low numbers of participants in this study and the ability of the triathletes to cope well with the elevations in training loads over the season. In conclusion, the studies in this thesis suggest that the exercise-induced responses of salivary C and T do alter due to an intensification of training loads. This alteration presents as a blunting of the exercise-induced responses of these salivary hormones. The 55/80 cycle bout can highlight this blunted response in both recreationally active and elite athlete male populations and therefore may be a useful tool to examine exercise-induced adaptations in salivary C and T concentrations caused by periods of intensified training.

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Talbot, Chris. "Physiological and biomechanical responses during high intensity upper body exercise." Thesis, University of Northampton, 2013. http://nectar.northampton.ac.uk/8886/.

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Trapp, Ethlyn Gail Medical Sciences Faculty of Medicine UNSW. "Effect of high intensity exercise on fat loss in young overweight women." Awarded by:University of New South Wales. School of Medical Sciences, 2006. http://handle.unsw.edu.au/1959.4/25182.

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This thesis investigated the effect of high intensity, intermittent exercise (HIIE) on fat loss in young, sedentary women. It attempted also to identify possible mechanisms underpinning exercise-induced changes in adiposity. Study 1 investigated some of the metabolic and hormonal responses to two variations of HIIE. Sixteen female subjects were tested. The first session involved a cycle ergometer VO2peak test. The next two sessions were completed in random order. After baseline measures the women did 20 min of HIIE. There was a short bout exercise of 8 s work, followed by 12 s relative rest and a long bout exercise of 24 s work followed by 36 s relative rest. Seven subjects had excess postexercise oxygen consumption (EPOC) and resting metabolic rate determined. Both exercise modalities made significant demands on the participants??? oxygen delivery systems. RER diminished over the 20 min of exercise and plasma glycerol concentrations increased. Lactate concentrations rose. Catecholamine concentrations were elevated postexercise. There was an elevated EPOC associated with above baseline fat utilisation. Study 2, a 15-week training study, was a randomised controlled trial comparing the effects of short bout HIIE and steady state (SS) exercise on fat loss. Forty-five women were randomly assigned to one of three groups: HIIE, SS, or control. Preliminary and posttraining testing included a DEXA scan and a VO2peak test including blood collection. All participants completed 3-d diet diaries and maintained their current diet for the course of the study. Participants exercised three times a week for the next 15 weeks under supervision. The HIIE group did 20 min of HIIE (8 s work:12 s rest) at a workload determined from the VO2peak test. The SS group cycled at 60%VO2peak , building to a maximum of 40 min exercise. Both exercise groups increased VO2peak . The HIIE group had a significant loss of total body mass (TBM) and fat mass (FM) when compared to the other groups. There was no change in dietary intake. There have been a number of studies examining the acute effects of HIIE but, to our knowledge, this is the first study examining the chronic effects of this particular exercise protocol.

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Chidnok, Weerapong. "Fatigue during high-intensity exercise : relationship to the critical power concept." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/12163.

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The hyperbolic power-duration relationship for high-intensity exercise is defined by two parameters: an asymptote (critical power; CP) reflecting the highest sustainable rate of oxidative metabolism, and a curvature constant (W'), which indicates a fixed amount of work that can be completed above CP (W>CP). According to the CP model of bioenergetics, constant work rate exercise above CP depletes the capacity-limited W' with fatigue occurring when W' is completely expended. The complete depletion of W' has been reported to occur when VO2max is attained and a critical degree of muscle metabolic perturbation (decline of finite anaerobic substrates and accumulation of fatigue-related metabolites) is reached. However, while the CP model is effective at predicting metabolic perturbation and the tolerable duration of severe-intensity constant work rate (CWR) exercise, it is unclear if metabolic perturbation and exercise performance can be explained by the CP model when different methods of work rate imposition are applied. Therefore, the purpose of this thesis was to: 1) investigate the efficacy of the CP concept to predict performance in exercise tests using different work rate forcing functions; and 2) explore whether the physiological bases for W' are consistent across different methods of work rate imposition. In study 1, compared to severe-intensity CWR exercise, the tolerable duration of intermittent severe-intensity exercise with heavy- (S-H) moderate- (S-M) and light-intensity (S-L) ‘recovery’ intervals was increased by 47%, 100% and 219%, respectively. W>CP (W') was significantly greater by 46%, 98%, and 220% for S-H, S-M and S-L, respectively, when compared to S-CWR, and the slopes for the increases in VO2 and iEMG were progressively lowered as the recovery work rate was reduced. In study 2, both the VO2max and W>CP were similar across incremental cycling protocols that imposed a fixed ramp rate and cadence (4.33 ± 0.60 L•min-1; 14.8 ± 9.2 kJ), a fixed ramp rate with cadence self-selected by the subjects (4.31 ± 0.62 L•min-1; 15.0 ± 9.9 kJ) and a step incremental test where subjects were instructed to select power output according to prescribed increments in ratings of perceived exertion (4.36 ± 0.59 L•min-1; 13.0 ± 8.4 kJ). In study 3, the VO2max and W>CP were also not different across a 3 min all-out cycling test (4.10 ± 0.79 L•min-1; 16.5 ± 4.0 kJ), cycling at a constant work rate predicted to lead to exhaustion in 3 min until the limit of tolerance (4.20 ± 0.77 L•min-1; 16.6 ± 7.4 kJ) and a self-paced 3 min work-trial (4.14 ± 0.75 L•min-1; 15.3 ± 5.6 kJ). In study 4, after completing severe-intensity exercise (>CP) to exhaustion, muscle homeostasis ([PCr], pH, [ADP] and [Pi]) returned towards baseline and subjects were able to exercise for at least 10 min at a heavy-intensity work rate (<CP); however, when the work rate was lowered but remained in the severe-intensity domain (>CP), muscle metabolites ([PCr], pH, [ADP] and [Pi]) did not recover and exercise tolerance was severely limited (39 ± 31 s). Finally in study 5, during severe-intensity intermittent knee extension exercise, the tolerable duration of exercise was 304 ± 68 s when 18 s recovery was allowed and was increased by ~69% and ~179% when the intermittent recovery periods were extended to 30 s and 48 s, respectively. The increased exercise tolerance with longer recovery periods occurred in concert with increased W>CP (3.8 ± 1.0 kJ, 5.6 ± 1.8 kJ and 7.9 ± 3.1 kJ for the intermittent protocols with 18, 30 and 48 s of recovery, respectively) and a delayed attainment of critical intramuscular metabolite concentrations ([PCr], pH, [ADP] and [Pi]). Therefore, the results of this thesis demonstrate that fatigue during various high-intensity exercise protocols is influenced by the capacity to complete work above the CP (W') and that W' depletion is linked to the attainment of VO2max and the attainment of critical levels of intramuscular [PCr], pH, [ADP] and [Pi]. These findings suggest that the CP model can be adapted to predict the degree of metabolic perturbation and exercise performance across a range of exercise settings in humans.

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Joo, Chang Hwa. "Effect of post-exercise cold water immersion on molecular responses to high-intensity intermittent exercise." Thesis, Liverpool John Moores University, 2015. http://researchonline.ljmu.ac.uk/4457/.

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The balance between the stress of training and competition and sufficient recovery is critical within the development of athletic performance. This stems from the need to recover between successive intense periods of exercise and provide sufficient time through which to adapt to the prescribed training stimulus. Cold water immersion (CWI) is now widely used by athletes to enhance the rate of recovery following training and competition. However, little information currently exists with respect to its influence on skeletal muscle adaptation. Therefore, the aim of this thesis was to investigate the impact of CWI on acute markers of adaptation in human skeletal muscle following low-damaging high-intensity intermittent exercise. The aim of study 1 (Chapter 4) was to devise a low-damaging high-intensity intermittent running protocol which would be used as the criterion mode of exercise in future studies within the thesis. The exercise was comprised of 60-min of high-intensity intermittent exercise (8 × 3-min bouts at 90% V ̇O2max interspersed with 3-min recovery) on a motorised treadmill. No significant reduction in maximal voluntary contraction of the quadriceps was observed immediately following completion of the exercise protocol or during the subsequent 7 d period compared to pre-exercise values (P = 0.59). Creatine Kinase (CK) concentrations remained similar to baseline following exercise (P = 0.96). Myoglobin (Mb) content increased following exercise (P = 0.01). However, values returned to baseline after 24 h (P = 0.32). These results suggest the high-intensity intermittent running protocol induced changes in physiological and subjective indices consistent with the effects of low muscle damaging as opposed to those changes normally associated with exercise-induced severe muscle damage. The purpose of the second study (Chapter 5) was to examine the effects of CWI (2 × 5-min (8oC)) on acute markers of skeletal muscle adaptation at rest. Rectal temperature remained similar throughout the CWI protocol (P = 0.36). However, significant reductions in skin (thigh and calf) and muscle temperature were observed immediately post-immersion and the post-immersion period (P < 0.05). Noradrenaline was significantly increased 3 h (355.7 ± 181pmol/l) and 6 h (390.9 ± 131pmol/l) post-immersion compared to baseline (P < 0.01). Muscle PGC-1α (3 h, 1.3 ± 0.2-fold; 6 h, 1.4 ± 0.3-fold) and VEGF165 (3 h, 1.9 ± 1.4-fold; 6 h, 2.2 ± 1.0-fold) mRNA expression were significantly increased at 3 h (PGC-1α, P < 0.001; VEGF165, P = 0.03) and 6 h (PGC-1α, P < 0.001; VEGF165, P = 0.009) post-immersion, respectively. These results indicate that CWI enhances the upstream signalling pathways associated with mitochondrial biogenesis and angiogenesis in human skeletal muscle at rest. The aim of the third study (Chapter 6) was to establish whether post-exercise CWI further enhances the upstream signalling pathways associated with mitochondrial biogenesis and angiogenesis in human skeletal muscle. On each occasion, participants rested passively (Cont) or undertook 2 × 5-min of CWI (8oC) at twenty minutes after completing the intermittent exercise protocol. Rectal temperature remained similar between CWI and Cont conditions during the 3 h post-exercise recovery period (P > 0.05), however, skin (thigh and calf) and muscle temperature were reduced in the CWI condition compared to Cont (P < 0.05). PGC-1α mRNA expression was significantly increased 3 h post-exercise under both conditions (CWI, P < 0.001; Cont, P = 0.003) with greater expression observed in CWI (CWI, 5.9 ± 3.1-fold; Cont, 3.4 ± 2.1-fold; P < 0.001). VEGF165 and VEGFtotal mRNA were greater in CWI (2.4 ± 0.6-fold, 2.3 ± 0.4-fold) compared with Cont (1.3 ± 0.5-fold, 1.0 ± 0.3-fold) at 3 h post-exercise (P = 0.01, P < 0.001). These findings demonstrate that post-exercise CWI increases the expression of upstream signalling pathways associated with mitochondrial biogenesis and angiogenesis in human skeletal muscle compared with exercise alone. Study 4 (Chapter 7) examined the influence of the repeated post-exercise CWI on upstream signalling pathways associated with mitochondrial biogenesis and angiogenesis in human skeletal muscle. On each occasion, participants rested passively or undertook 3 × 10-min of CWI (8oC) at twenty minutes after completing the intermittent exercise protocol, 1 h and 2 h post-exercise. Rectal temperature was reduced during the 3rd bout of CWI and subsequent 30-min period compared to Cont (P < 0.05). Skin temperature (thigh and calf) remained consistently lower during the immersion periods in CWI compared with Cont (P < 0.05). Muscle temperature was reduced before the 2nd bout of CWI (-5.8 ± 0.3oC) compared with Cont (-1.9 ± 0.4oC) and remained until 50-min after the 3rd immersion (P < 0.05). Noradrenaline were significantly greater at 3 h and 6 h following exercise in CWI (662 ± 139pmol/l, 518 ± 158pmol/l) compared with Cont (307 ± 162pmol/l, 245 ± 156pmol/l) (P < 0.05). PGC-1α mRNA expression was higher after 3 h post-exercise in the Cont (2.4 ± 1.7-fold) than CWI (1.8 ± 1.0-fold) conditions respectively (P = 0.06). At 6 h post-exercise, PGC-1α mRNA expression was greater in CWI (2.6 ± 1.4-fold) compared to Cont (1.7 ± 1.7-fold) (P = 0.03). VEGF165 and VEGFtotal mRNA increased more than ~1.6-fold at 3 h and 6 h following exercise and were similar between conditions (P > 0.05). These results indicate that increasing the repeated post-exercise CWI does not further increases the expression of upstream signalling pathways associated with mitochondrial biogenesis and angiogenesis in human skeletal muscle. This thesis provides novel findings concerning the influence of high-intensity intermittent exercise and post-exercise CWI on cellular and molecular adaptations in human skeletal muscle. These findings may offer important insights for athletes wishing to maximize training adaptations.

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Sletten, Nathan Robert. "Effects of high-intensity interval exercise on vasodilator function in children." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62809.

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Purpose: Exercise training can improve vascular function through anti-atherogenic effects on the vascular endothelium, a response which can be discerned following individual bouts of exercise. Although well characterized in adults, the effect of exercise intensity on the acute recovery patterns of vasodilator function is unknown in children. Study Design: Nine children (age = 10.5 ± 1.5 y, 6 girls) completed 1) high-intensity interval exercise (HIIE, six 1-minute sprints at 90% peak power (Wmax), with 1-minute recovery) and 2) moderate-intensity exercise (MIE, 15 minutes at 44% Wmax, total external work-matched to HIIE). Superficial femoral artery (SFA) diameter, blood flow, shear rates, and flow-mediated dilation (FMD) were measured before (Pre), immediately following (Post), and 60 minutes following (Post60) the exercise trials using duplex ultrasound. Results: Baseline diameter increased similarly following both HIIE (Pre 4.25 ± 0.42 mm, Post 4.76 ± 0.42 mm) and MIE (Pre 4.29 ± 0.49 mm, Post 4.62 ± 0.49 mm), returning to pre-exercise values 60 minutes later. Blood flow and antegrade shear rate were increased following HIIE and MIE, but to a greater extent after HIIE (P < 0.05). Retrograde shear rate was attenuated following both exercise conditions, remaining lower 60 minutes after exercise (P’s < 0.001). FMD was attenuated Post compared to Pre following HIIE (Δ -2.8%) and MIE (Δ -2.5%) (P’s < 0.05) and recovered to pre-exercise values with no difference between Post60 and Pre FMD. When FMD was corrected to account for changes in baseline diameter, there was no longer a significant main effect of time (P = 0.34) making the post-exercise nadir in FMD negligible. Conclusions: Acute bouts of external work-matched HIIE or MIE exert a similar impact on shear-mediated conduit artery vasodilation and FMD in children and this is reversible 60 minutes post-exercise. This suggests the mechanisms that govern the acute FMD response in adolescents and adults may be dissimilar in children. Graduate Studies, College of (Okanagan) Graduate

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Saunders, B. "Effects of buffering agents on high-intensity exercise performance and capacity." Thesis, Nottingham Trent University, 2012. http://irep.ntu.ac.uk/id/eprint/229/.

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High-intensity exercise results in hydrogen ion accumulation, which can have a deleterious effect on muscle function, and thus exercise tolerance. Buffering agents are commonly used to enhance exercise performance and capacity. Two such agents, β-alanine and sodium bicarbonate, increase intracellular and extracellular buffering capacity, which could contribute to an improved performance and capacity during exercise limited by increasing acidosis. Despite this, studies on the ergogenic effects of β-alanine are still in their infancy, and research on sodium bicarbonate remains equivocal. The aim of this thesis was to investigate the separate and combined effects of β-alanine and sodium bicarbonate on high-intensity exercise performance and capacity using various exercise modalities. The CCT110%, a cycling capacity test, was shown to be reliable (Chapter 4A), and subsequently employed to investigate the effect of sodium bicarbonate (Chapter 4B), β-alanine and co-supplementation of the two (Chapter 4C). Sodium bicarbonate supplementation was shown to improve total work done during the CCT110% (+4.8%), only when those experiencing gastrointestinal discomfort were removed from analyses, as was β-alanine (+14.6%); co-supplementation of the two did not confer any further benefits above β-alanine alone. Neither sodium bicarbonate (Chapter 5A) nor β-alanine or co-supplementation of the two (Chapter 5B) improved 5 x 6 s repeated running sprints (all P > 0.05). Sprint performance during the Loughborough Intermittent Shuttle Test was unaffected by β-alanine supplementation in elite (P = 0.63) and non-elite (P = 0.58) games players (Chapter 6), although YoYo Intermittent Recovery Test Level 2 performance was improved (+34.3%) with β-alanine in amateur footballers during a competitive season (Chapter 7). High-intensity match activities during competitive match play were unaffected by β-alanine supplementation (Chapter 8). The results in this thesis showed that β-alanine was effective at improving exercise capacity but not exercise performance. Results suggest sodium bicarbonate, and co-supplementation with β-alanine, may improve exercise tolerance although further research is warranted.

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Allison, Wayne. "Effects of high-intensity intermittent exercise on decision-making in soccer." Thesis, Sheffield Hallam University, 2009. http://shura.shu.ac.uk/20618/.

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The aim of this thesis was to identify physiological factors associated with decision making performance of soccer players. If a decrement in decision-making performance was observed, a second aim would be to assess the extent to which soccer players' decision-making capability could be improved and trained. To achieve these aims there were four specific objectives: 1) To measure decision-making in soccer players using a soccer-specific protocol to assess decision-making and determine the reproducibility of the protocol's measures; 2) determine the effect of soccer-specific intermittent exercise on decision-making capability of soccer players; 3) assess the influence of repeated sprints and sprint-recovery duration on decision-making performance of soccer players and 4) assess the extent to which decision-making can be trained, by comparing perceptual video training with a soccer-specific field-based perceptual training programme. Reproducibility of decision-making measures was determined by test-retest method. Ten male participants performed 10 decision-making test trials, rested for one hour then completed a further 10 trials on two occasions. Analysis revealed response time Intraclass Correlation Coefficient (ICC) = 0.91 and response accuracy ICC = 0.80. Coefficient of variation for response time was 3.4% and for response accuracy 4.6% indicated measures were reproducible. Using this protocol, 15 participants performed an experimental trial (decision-making task, before and after an intermittent treadmill protocol) and a control trial (before and after decision-making task) on separate occasions. Means were compared using a fully repeated measures factorial analysis of variance. There was an interaction for response time (p < 0.01), d = 0.64 (large) and an interaction in response accuracy (p < 0.01), d = 0.84 (large) which indicated that players' decision-making performance was impaired probably because of the physiological strain imposed. Investigating these findings, 10 male participants performed, the decision-making task separated by 10 x 10-s repeated sprints with either a 15-s or a 30-s recovery period on different occasions. Means were compared using a fully repeated-measures factorial analysis of variance. There was an interaction for response time (p < 0.01), d = 0.42 (moderate). There was also an interaction for response accuracy (p < 0.01), d = 0.85 (large) highlighting, response time and accuracy were adversely affected as a consequence of the repeated sprints. As a decrement in decision-making was observed, 24 male participants were divided randomly into one of four groups (control, placebo, perceptual training and a field-based decision-making training group) of six participants. Repeated sprints and decisionmaking performance was assessed before and after a six-week perceptual training intervention and during a retention test after a further seven days. Groups were compared using a two-way multivariate analysis of variance, by groups and occasion. Players who underwent field-based training improved their response time (p < 0.01), d= 0.34 (small) and response accuracy (p < 0.01), d = 0.88 (large) after the six-week training intervention. This illustrated that field-based decision-making training facilitated the acquisition of perceptual skill in soccer and could be used as part of players' overall training programme.

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16

Wootten, David F. "Short Term Time Course Skeletal Responses to High Intensity Physical Exercise." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/27880.

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The purpose of this randomized controlled trial was to investigate temporal skeletal responses to short-term high intensity physical activity. Twenty-eight normal active females [age: 20.7 +/- 2.1 yr (mean +/- SD)] were randomized into exercise (EX, n = 15) or control (CN, n = 13) groups. The exercise group trained 6 days/wk for 6 wk, which consisted of maximal isokinetic knee flexion/extension 3 days/wk, combined with 3 days/wk running. The purpose was to expose the tibiae to a period of abruptly increased loading forces. Tibial bending stiffness (EIMRTA), and serum concentrations of biochemical markers of bone formation [osteocalcin (OC)], and bone resorption [n-telopeptide of type I collagen (NTx)] were measured at baseline, 2 wks, 4 wks, and 6 wks. Isokinetic concentric knee extension/flexion peak torque, as well as total body and site-specific bone mineral density (BMD) were measured at baseline and 6 wk. After training, the exercise group significantly increased (p < 0.05) isokinetic concentric peak torque for the dominant (13.6%) and non-dominant (5.7%) quadriceps, as well as dominant (7.7%) and non-dominant (9.5%) hamstrings, compared to the controls. No differences for total body or site-specific BMD were noted. A two-way multivariate repeated measures ANOVA revealed no timeâ ¢group interactions for composite tibial bending stiffness [(EIMRTA); p = 0.57] or the biochemical markers of bone turnover [(OC and NTx); p = 0.15] across the four sampling periods. While there were no main effects for group, a trend for time (p = 0.051) for composite EIMRTA was observed. The exercise group demonstrated a 20% increase in EIMRTA from baseline (74.8 +/- 22.3 Nm2) to 6 wk (89.8 +/- 24 Nm2), compared to controls who demonstrated a 4% increase (Baseline 86.5 +/- 23.8 Nm2; 6 wk 90 +/- 23.7 Nm2). Significant group differences (p = 0.05) were noted for OC, but not NTx. Differences (p < 0.05) for OC were observed at baseline [13.2 +/- 2.4 ng/ml (CN), 15.6 +/- 2.7 ng/ml (EX)], and follow-up ANCOVA revealed no differences for subsequent sampling periods. Main effects for time were found for OC and NTx (p < 0.001). Main effects for time in OC were attributable to changes in the exercise group (p < 0.01) and NTx (p < 0.01), but not the control group. Ph. D.

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17

Odendal, Elsabe. "Pulmonary function and acid-base balance high intensity constant-load exercise." Master's thesis, University of Cape Town, 1993. http://hdl.handle.net/11427/27123.

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The possibility that an inadequate response of the pulmonary system might limit high intensity exercise in man has received increasing attention over the past few years. However, very few scientific investigations have focused systematically on pulmonary function during high intensity constant-load exercise. Furthermore, many studies have examined only one part of the pulmonary system during exercise and some have not included blood gas measurements as a measure of the adequacy of pulmonary function. The studies reported in this thesis were designed to investigate the possible failure of the gas exchanging and pump functions of the pulmonary system during high intensity constant-load exercise. In particular, the aim was to determine the extent to which the pulmonary system might be a factor causing fatigue during this form of exercise.

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18

Tyler, Alyssa N. "The Effect of High Intensity Exercise on pH and Inflammatory Biomarkers." Kent State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=kent1405583783.

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19

Ball, Derek. "Diet, acid-base status and the performance of high intensity exercise." Thesis, University of Aberdeen, 1992. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU045175.

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The aim of the present experiments was to investigate the effects of dietary components and composition on acid-base status. It was hoped that those dietary components which exert the greatest effect on acid-base would be identified. In a second series of experiments the role of diet-induced changes on the performance of high intensity exercise was investigated. The sodium salts of weak organic acids were administered after an overnight fast and their effects on blood acid-base status were observed. An alkalinising effect on blood and urine was observed over 3 and 24 hours respectively. In the next study the sodium salts were administered for five consecutive days; blood and urine acid-base status were measured 24 hour after ingestion. Under these circumstances the salt-induced alkalosis was only observed on urine. Blood acid-base status had, after 24 hours, returned to pre-ingestion values. The alkalinising effect on urine was sustained for as long as the sodium salts were consumed. However, upon cessation of the salt ingestion urine acid-base status had returned to the pre-ingestion values within 24 hours. In the third experiment the chronic effects of different macro nutrient intakes was investigated in two groups of matched female subjects. The omnivorous group had a higher dietary intake of protein than the vegetarian subjects. There was no biologically significant difference in blood acid-base status between the two groups. As a consequence of the higher protein intake the urinary titratable acid output of the omnivorous women was higher than that of the vegetarians. Despite the same dietary intake of calcium the omnivorous subjects had a higher urinary excretion of calcium than the vegetarians. It is thought the acidifying effect on urine from the higher protein intake of the omnivorous women was responsible for their greater urinary calcium excretion.

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20

Sproule, John Service. "Fluid manipulation strategies and running economy during prolonged high-intensity exercise." Thesis, Loughborough University, 1996. https://dspace.lboro.ac.uk/2134/25587.

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Running economy (RE) is defined as the rate of oxygen consumption at a given submaximal running velocity. Whilst the concept of running economy is well documented, little information is available about the to daily variation in RE, variation in RE within prolonged running bouts and the effects on RE of exercise-induced dehydration. Thus, the principal aim of this research was to investigate these aspects and attempt to contribute further knowledge and understanding of RE. The purpose of the first study (Chapter 4), was to investigate the daily variation in RE in twenty one habitually active Singaporean men (V0₂max = 51.6 ± 5.8 ml.kg⁻¹ min⁻¹). The RE was measured over three consecutive days during treadmill running at 3.33 m.s⁻¹, and at running speeds representing relative exercise intensities of 60% and 85% V0₂max (randomly assigned in a counterbalanced design). The running bouts were of 10 min duration at each speed, with 5 min rest between each running bout. The group mean (±SD) VO₂ during submaximal running at 3.33 m.s⁻¹ (82 ± 5.7% V0₂max) was 44.5 (±2.1), 43.8 (±2) and 44.2 (±2) ml.kg⁻¹ min⁻¹ for days one, two and three respectively. The mean coefficient of variation (CV) for RE at 3.33 m.s⁻¹ was 2.54 % (range = 0.24 - 5.41%). The group mean VO₂ during submaximal running at 60% and 85% VO₂max was similarly invariant over the three consecutive days. The results showed no differences in daily RE for the group (p > 0.05). The results suggest that for the individuals in this study RE does not change on a daily basis.

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Beale, Louisa. "High intensity intermittent exercise training in patients with chronic heart failure." Thesis, University of Brighton, 2011. https://research.brighton.ac.uk/en/studentTheses/bad848f5-5103-4ea0-ad97-7b382e403732.

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High intensity intermittent exercise may provide an alternative means of exercise training with greater health benefits than the lower exercise doses used in current practice, yet definitive guidelines for intermittent exercise are lacking. This thesis examines the methodology for intermittent exercise prescription, and assesses the efficacy of an intermittent exercise training intervention for chronic heart failure patients (CHF), thus providing a novel application in UK cardiac rehabilitation programmes.

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Collins, Jessica Rose. "Impact of High Intensity Interval Training Versus Traditional Moderate Intensity Continuous Training on Critical Power and the Power-Duration Relationship." BYU ScholarsArchive, 2021. https://scholarsarchive.byu.edu/etd/9185.

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Critical Power (CP) is the greatest power that a person can sustain for prolonged periods of time while maintaining steady state conditions. Work-prime (W’) is the amount of work that can be tolerated when exercising in non-steady-state conditions above CP. A person’s CP and W’ strongly influence the metabolic response and tolerance to exercise. PURPOSE: Compare the effect of equal amounts of moderate intensity continuous training (MICT) and high intensity interval training (HIIT) on CP and W’. Critical Power (CP) is the greatest power that a person can sustain for prolonged periods of time while maintaining steady state conditions. Work-prime (W’) is the amount of work that can be tolerated when exercising in non-steady-state conditions above CP. A person’s CP and W’ strongly influence the metabolic response and tolerance to exercise. PURPOSE: Compare the effect of equal amounts of moderate intensity continuous training (MICT) and high intensity interval training (HIIT) on CP and W’. METHODS: Twenty-two (10 female) untrained, young (26.4 ± 0.9 years) adults completed 8 weeks of cycling training (40 min, 3  per week) administered as either MICT cycling (44% max work rate achieved during a maximal graded exercise test; GXTmax) or HITT cycling (4 bouts at 80% GXTmax for 4 min with recovery intervals between). Cycling V̇O2max, CP, W’ and Anaerobic Capacity (i.e., Wingate) were determined before and after training. Specifically, CP was assessed with the work-over-time method derived from 4–5 constant-power tests to exhaustion. RESULTS: MICT (n = 11) and HIIT (n = 11) groups completed the same amount of work over the course of the training (P = 0.76). CP significantly increased in both groups, but to a greater extent in the HIIT group (MICT: 15.7 ± 3.1% vs. HIIT: 27.5 ± 4.3%; P = 0.04). The work that could be performed above CP (i.e., W’) was not significantly impacted by training (p = 0.76). V̇O2max significantly increased in both groups (P < 0.01), and the magnitude tended to be greater in the HIIT group (MICT: 8.3 ± 2% vs. HIIT: 14 ± 2.6%; P = 0.09). Interestingly, the training-induced change in CP was not significantly related to the training-induced change in V̇O2max. The training-induced increase in CP exhibited a positive curvilinear relationship with the training intensity, expressed as a percentage of the initial CP, with those performing the same workout at a greater percentage of CP exhibiting greater training-induced increases in CP (R2 = 0.49, P < 0.01). CONCLUSION: HIIT elicits approximately twice the increase in CP than an equal amount of MICT in untrained young adults. Moreover, the magnitude of increase in CP is strongly related to the intensity of the exercise, relative to CP, even when exercising at the same percentage of GXTmax. Thus, exercise may be more effectively prescribed relative to CP, rather than V̇O2max or GXTmax.

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23

Willcocks, Rebecca. "Investigation of metabolic responses to exercise in adolescents and adults during high intensity exercise and recovery." Thesis, University of Exeter, 2011. http://hdl.handle.net/10036/3221.

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Children and adolescents are thought to use oxidative metabolism to a greater extent than adults during high intensity exercise. The studies reported in this thesis examine the nature and implications of age-related differences in muscle metabolism during high intensity exercise and recovery. Chapter 4 concluded that during heavy intensity exercise, phosphocreatine (PCr) kinetics did not differ with age or sex, while Chapter 5 revealed that during very heavy intensity exercise, the fundamental τ was slower and slow component amplitude greater in men compared with adolescent boys, indicating that exercise intensity might play a role in determining age-related differences in muscle metabolism. In Chapter 6, two bouts of very heavy intensity exercise were completed, and prior exercise reduced the PCr slow component amplitude in men but not boys. Deoxyhaemoglobin (HHb) kinetics was faster in adolescents compared with adults during both heavy and very heavy intensity exercise, indicating that matching of oxygen delivery to oxygen utilisation is less precise at the onset of exercise in adolescents compared with adults. PCr recovery from high intensity exercise was faster in boys than men, but not different in girls and women, as described in Chapter 7. The speed of PCr recovery was correlated with maturity in adolescents, but was not correlated with end-exercise [PCr] or pH. Two different tests to measure mitochondrial capacity in adolescents were evaluated in Chapter 8, and a fitted curve and gated test were both used to determine PCr recovery kinetics. Finally, in Chapter 9, age-related differences in muscle metabolism and oxygenation during fatiguing exercise were examined; a strong trend for greater fatigue in adults compared with adolescents was accompanied by greater metabolic perturbation in adults. Overall, these data show that muscle metabolism and oxygenation differs between adolescents and adults during and following very high intensity exercise.

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24

Boynton, Jason R. "The effects of environmental temperature on high-intensity interval training." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2020. https://ro.ecu.edu.au/theses/2341.

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Endurance athletes typically spend the large majority of training (> 70%) at low intensities (i.e. below lactate threshold) coupled with short and intermittent bouts of high-intensity exercise or interval training (HIIT). Despite HIIT being a relatively small part of training in terms of duration, it has a substantial effect on the adaptations to endurance training. While it is well-established endurance exercise performance is affected in both hot and cold environmental conditions, the effect ambient temperature (TA; frequently referred to as environmental temperature) has on HIIT as performed by an endurance athlete population is not well understood. Therefore, the overall purpose of this thesis was to investigate the effects TA has on HIIT in an endurance trained population. Specifically, this thesis aimed to increase the understanding of how TA acutely affects performance and physiological responses during high-intensity intervals (Study 1); how repeated exposure to TA manipulates physiological responses during high-intensity intervals (Study 2), and how TA affects performance outcomes of a HIIT intervention (Study 3). In Study 1, eleven well-trained cyclists completed 4 interval sessions at 5°C, 13°C, 22°C, and 35°C (55 ± 13% RH) in a randomised order. Each session involved 5 x 4-minute intervals interspersed with 5 minutes of recovery. During the intervals, power output, core temperature (TC), oxygen consumption (VO2), and heart rate (HR) were recorded. It was hypothesized that the 13°C condition would have the highest mean power output compared to the other TA conditions. However, mean session power output for 13°C (366 ± 32 W) was not significantly different than 5°C (363 ± 32 W), 22°C (364 ± 36 W), or 35°C (352 ± 31 W). Power output was lower in the 5th interval of the 35°C condition, compared with all other TA. TC was higher in 22°C compared with both 5°C and 13°C (P= .001). VO2 was not different across TA. HR was higher in the 4th and 5th intervals of 35°C compared with 5°C and 13°C. It was concluded well-trained cyclists performing maximal high-intensity aerobic intervals can achieve near optimal power output over a broader range of TA than previous literature may indicate. Study 1 indicated TA had acute effects on performance and physiological responses during high-intensity aerobic intervals, especially in terms of cardiovascular stress. However, whether acute cardiorespiratory and thermoregulatory responses during high-intensity intervals change as a result of repeated TA exposures (i.e. during HIIT) was unknown. In Study 2, 20 trained cyclists and triathletes completed a 4-week (8 session) HIIT intervention in either cool (13°C) or hot (35°C) conditions. The HIIT intervention utilized the interval protocol from Study 1 and recorded cardiopulmonary and thermoregulatory measures during the first (INT8) and last (INT8) sessions. It was observed that time spent at or near maximal oxygen consumption (VO2max) during HIIT was greater in 13°C (877 ± 297 seconds) than 35°C (421 ± 395 seconds), but did not change for either TA condition between INT1 and INT8. HR was not significantly different between 13°C (164 ± 9 bpm) and 35°C HIIT (164 ± 12 bpm). TC significantly decreased in 35°C HIIT between INT1 and INT8. These results potentially indicate the relationship between time spent at or near VO2max and cardiovascular strain during HIIT is influenced by TA. Additionally, HIIT performed intermittently (~2x per week) at 35°C resulted in demonstrated evidence for heat acclimation in endurance athletes. Study 1 and Study 2 provided findings for performance, cardiorespiratory, and thermoregulatory responses during acute high-intensity interval sessions and after repeated exposure to TA. In particular, differences in time spent at or near VO2max between 13°C and 35°C HIIT, and changes in thermoregulatory responses over the course of a HIIT intervention both have the potential to affect endurance performance outcomes and coinciding physiological responses. In order to investigate this, Study 3 evaluated submaximal warm-ups and 20 km time-trials in temperate conditions (22°C) before (TT1) and after (TT2) the HIIT interventions from Study 2. Gross mechanical efficiency (GME) was measured during the warm-up (at 50% peak power output), whilst power output and HR were measured during the 20 km TT. Rate of perceived exertion (RPE) and body temperature (TB) were measured through the warm-up and time-trial. It was demonstrated that time-trial power output was increased after HIIT interventions in both the 13°C (3%; HIIT13) and 35°C (7%; HIIT35), yet no differences between groups for power output, HR, or RPE were noted. Within subject increases for HR and RPE during the 20 km time-trial were noted in HIIT13, but not in HIIT35. GME approached a significant decrease (P= .051) in HIIT13. A significant interaction in TB was observed between groups and TT1 and TT2 during both the 20 km time-trial and submaximal warm-up. These findings indicate that HIIT performed in hot and cool conditions result in similar temperate time-trial performance outcomes. However, changes in cardiorespiratory, thermoregulatory, and subjective responses during aerobic exercise after a HIIT intervention appear to be dependent on the TA HIIT is performed in. The results of this thesis demonstrate TA acutely affects performance, and cardiorespiratory and thermoregulatory responses during high-intensity intervals; repeated exposures to TA during HIIT can stimulate changes in thermoregulatory responses; and TA exposure during HIIT has limited effect on temperate endurance performance, yet affects coinciding cardiorespiratory, thermoregulatory, and subjective responses. These findings will assist coaches and athletes to make better informed decisions relating to HIIT prescription and acclimating endurance athletes to TA.

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25

Wessel, Paige. "Accuracy of Commercial Fitness Trackers During High-Intensity Functional Training." TopSCHOLAR®, 2016. http://digitalcommons.wku.edu/theses/1634.

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Commercially available fitness trackers have been found to accurately measure steps and caloric expenditure during walking and running activities. Circuit-style, highintensity functional training (HIFT) has become increasingly popular because it is inexpensive and effective in improving muscular strength and cardiovascular fitness. PURPOSE: To evaluate the accuracy of five accelerometers (ActiGraph GT3X, Nike Fuelband, Fitbit One, Fitbit Charge HR, and Jawbone UP Move) in estimating energy expenditure while performing an acute bout of HIFT. METHODS: Participants (n = 47) underwent baseline testing and at least 48 hours later, each participant completed the main test: a 15-minute workout consisting of 12 repetitions each of 7 different exercises; performed circuit-style by completing as many rounds as possible. During the main test, each participant wore the Cosmed K4b2 portable metabolic analyzer (PMA) and five different accelerometers. RESULTS: Four of the five fitness trackers reported lower (p <0.01) total caloric expenditure values compared to the PMA during the acute bout of HIFT. The waist-mounted device (ActiGraph, 182.55 ± 37.93 kcals) most closely mimicked caloric expenditure compared to the PMA (Cosmed, 144.99 ± 37.13 kcals) as indicated by an insignificant p value (0.056). Systematic differences between the activity monitors were calculated using an Intraclass Correlation (ICC) with an ICC = -0.032. The ICC of F (46,235) = 0.812 (p = 0.799) was not significant at the predetermined 0.05 alpha level. A Repeated Measures ANOVA showed that when compared to the Cosmed, all activity monitors were significantly different at the 0.05 alpha level. The Fitbit One and the Fitbit Charge HR were the only two activity monitors that are not significantly different from one another (p = 0.985). The range of error based on mean absolute percentage errors (MAPE) was lowest for the ActiGraph (15.1%) and highest for the Fitbit Charge HR (22.1%). CONCLUSION: The wrist- and hip-mounted fitness trackers do not accurately assess energy expenditure during HIFT exercise. Supported by: WKU Graduate School, NIGMS 2P20 GM103436-14; Institutional Development Award (IDeA) from National Institute of General Medical Sciences, National Institutes of Health, 5P20GM103436 and the WKU RCAP Grant 14-8007.

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Noonan, Benjamin Carter. "The Physiological Effects of Hockey Protective Equipment on High Intensity Intermittent Exercise." Yale University, 2006. http://ymtdl.med.yale.edu/theses/available/etd-06282006-133133/.

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Ice hockey is a contact sport played in a cold environment which leads to assumptions that players are not exposed to a thermal challenge. The purpose of this study was to test the hypothesis that the wearing of hockey protective equipment during an exercise protocol designed to simulate a hockey game would induce a thermal challenge and lead to decrements in performance. In order to test this hypothesis and qualify the physiological responses, subjects performed a standardized protocol performed on a stationary cycle ergometer in an environmental chamber set at typical (12ºC) ice hockey ambient conditions. The simulation was performed twice; once while wearing cotton undergarments only (NP), and once while wearing cotton undergarments and the typical protective equipment worn during a hockey game (P). Work intensity during each trial was held constant and was evaluated by examining mean power output, which was similar under both P and NP conditions (348.2 W vs 352.08 W, P > 0.05) P vs NP, respectively. Body (37.18 ºC vs 36.58 ºC) and skin temperatures (34.12 ºC vs 28.85 ºC) were elevated in P vs NP, respectively (P<0.05). Core temperatures (37.50 ºC vs 37.41ºC) displayed a trend towards being higher in P vs NP particularly during the third period of simulation (P = 0.053). Sweat loss as a percent of body mass was greater in P vs NP (2.57% vs 1.18%, respectively P<0.05), which led to an increase in plasma osmolality (287 vs 283 mosmol/kg H2O, respectively P<0.05) working heart rate (83.7% vs 78.8% of maximum heart rate), resting heart rate (63.4% and 55.9% of maximum heart rate), and urine specific gravity (1.026 vs 1.017) for P vs NP respectively (each P<0.05). The drop-off in power from pre to post simulated game was examined in both conditions by the use of five repeated maximal six second sprints interspersed with 24 seconds of recovery. The drop-off in both peak (12.0% vs 0.2%) and mean power (14.5% vs 2.7%) was greater in P versus NP (P<0.05). Plasma lactate concentration was higher following the simulated game in P vs NP (9.64 vs 5.96 mmol/L, P<0.05) as was plasma norepinephrine (2274.0 vs 1366.9 pg/ml, P<0.05). Rating of Perceived Exertion increased by 30-53% in the P condition (P<0.05) even though power outputs were equivalent. The elevated body temperature and increased water loss appeared to increase glycolytic flux, which when coupled with the consequences of thermal stress, reduced power output and led to the perception of elevated work intensities during the simulated game.

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Fletcher, Deborah K. "The influence of caffeine on lymphocyte activation after prolonged high intensity exercise." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/7047.

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Many athletes consume caffeine for its known ergogenic effects. Since being legitimised by its 2004 removal from the World Anti-Doping Agency prohibited list of substances, caffeine s ability to enhance performance has led to its widespread use amongst the athletic population. However, despite caffeine s prevalence, little research has focused on the effect of caffeine ingestion on immune function both at rest and in response to exercise in humans. Therefore, the aim of this thesis was to investigate the influence of typically-used doses of caffeine (typical daily intake in training and competition doses) on aspects of innate and acquired immunity in response to prolonged exercise. At rest both a high (6 mg kg-1) and low dose (2 mg kg-1) of caffeine had little effect on antigen-stimulated T (CD4+ and CD8+) or natural killer (NK) lymphocyte activation, while a high dose of caffeine only increased the number of antigen-stimulated NK cells expressing CD69 1 h following caffeine ingestion (Chapter 4). In response to prolonged high intensity continuous cycling both high and low doses of caffeine increased the natural state of activation as well as the antigen-stimulated activation of NK cells 1 h after exercise cessation (Chapters 5 and 6). However, at the same time-point a high dose of caffeine decreased CD4+ and CD8+ cell activation (Chapter 5). One hour after high intensity intermittent shuttle running, a high dose of caffeine attenuated the exercise-induced increase in NK cell activation both in terms of the number of cells expressing CD69 and their geometric mean fluorescence intensity expression of CD69 (Chapter 7). These effects did not occur in response to intermittent exercise when 2 mg kg-1 caffeine was instead ingested in 3 repeated doses throughout the day (Chapter 7). In conclusion, the findings of this thesis demonstrate the complex actions of caffeine on antigen-stimulated T and NK lymphocyte activation 1 h after prolonged intensive exercise. However, the biological significance of these findings in terms of caffeine s potential to alter an individuals susceptibility to infection following prolonged high intensity exercise are yet to be determined.

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Chalari, Eleanna. "The effect of high-intensity intermittent exercise on biomarkers of oxidative stress." Thesis, University of Hull, 2017. http://hydra.hull.ac.uk/resources/hull:16424.

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There are evidence that high-intensity acute exercise can promote oxidative stress. High-intensity intermittent exercise (HIIE) is a type of structured physical training characterised by repeated bouts of high-intensity exercise interspersed by recovery periods. As the impact of intermittency during acute HIIE has not been extensively studied, it is possible that the repeated intensive bouts within HIIE could induce oxidative stress levels. Plasma biomarkers, including lipid hydroperoxides and markers of DNA damage, have been increasingly applied within acute exercise physiology research to measure oxidative stress. This thesis presents the experimental outcomes of research into the effect of different forms of HIIE on established and novel biomarkers of oxidative stress. For the 1st study (chapter 3) a liquid chromatography-mass spectrometry (LCMS) method was developed and optimised to measure DNA oxidation in plasma samples. Implementing a range of progressive analytical techniques, the method developed had a sensitivity to detect 8-hydroxy-2'-deoxyguanosine (8-Oxo-dG) in human plasma samples in the range of 5 – 500 nM. The implementation of this LC-MS method along with other oxidative stress biomarkers was thereafter applied to a randomised investigation of different high-intensity intermittent exercise protocols. The 2nd (chapter 4) and 3rd (chapter 5) studies considered the effect of different forms of intermittent exercise undertaken by 9 healthy, regularly active male participants (aged 21.0 ± 3.0 years). Each intermittent exercise session was performed for a total duration of 45 minutes. Each 45 minute exercise protocol consisted of 4 minute stages of high-intensity intermittent running at a mean 75% v!O2max, followed by 1 minute of passive recovery (halt of running). The experimental protocol was specifically designed to match for average speed, duration and distance but varied in either the intermittency (chapter 4) or the acceleration/deceleration (chapter 5). The effects of different forms of intermittent exercise (high, moderate, low) or different acceleration/deceleration components (high, moderate, low) in relation to oxidative stress biomarkers were determined. Results showed the absence of significant increases in all the biomarkers examined. However, significant variation in individual oxidative stress responses was observed. Within a final study, the 8-Oxo-dG method developed was compared to a widely used ELISA method, as there are indications in the literature that ELISA may overestimate 8-Oxo-dG. Determination of 8-Oxo-dG was undertaken on blood plasma samples from 30 chronic heart failure patients (males = 23, females = 7) recruited from the Academic Cardiology department at Castle Hill hospital, Hull, UK, as previous studies have characterised the heart failure syndrome to be associated with higher levels of oxidative stress. Results showed that the LC-MS method developed found no detectable levels of 8-Oxo-dG in plasma samples whereas ELISA showed quantifiable amounts of 8-Oxo-dG. Thus, this thesis presented that the impact of intermittency or acceleration/deceleration following acute HIIE does not induce significant oxidative stress as determined by plasma and serum biomarkers, including plasma 8-Oxo-dG.

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Paul, David R. "Carbohydrate oxidation during high-intensity exercise after a preexercise fat-rich meal /." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488194825666821.

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Greenhaff, Paul Leonard. "Diet, acid-base status and the metabolic response to high intensity exercise." Thesis, University of Aberdeen, 1988. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU010287.

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The aim of these experiments was to investigate the influence that dietary manipulation has upon acid-base balance and substrate availability at rest and during high intensity exercise. It was hoped to identify some of the mechanisms that may control the utilisation of energy substrate and influence the onset of fatigue during high intensity exercise. A pattern of dietary and exercise manipulation intended to alter carbohydrate (CHO) and fat availability was undertaken during the first two experiments. In addition to influencing energy substrate availability, the diet and exercise regimen also significantly influenced resting acid-base balance and high intensity exercise capacity. The reduction in exercise performance afer administration of a low CHO, high fat, high protein diet may have been due to the diet-induced acidosis produced by this diet. However, it is also probable that glycogen availability was influencing exercise performance in this situation. A fixed period of exercise under the same experimental conditions indicates that a higher than normal muscle glycogen content may dictate the pattern of substrate utilisation during high intensity exercise. In a second series of experiments it was demonstrated that dietary manipulation alone will influence acid-base balance and exercise capacity. A high fat, high protein diet will produce a metabolic acidosis but will not influence total muscle glycogen content. In this situation, it is unlikely that a reduction in high intensity exercise performance can be attributed to the availability of muscle glycogen. It is possible that a change in fat availability, rather than muscle glycogen content, will influence the pattern of substrate utilisation during high intensity exercise. However, it is unlikely that a change in fat availability will be responsible for the reduction in exercise capacity recorded after a high fat, high protein diet. The reduction in exercise capacity may be the result of a diet-induced acidosis. Although it is unlikely that dietary acidosis will influence H+ efflux from muscle it may influence pre-exercise muscle buffering capacity. The resulting greater decline in muscle pH during exercise after a high fat, high protein diet may influence muscle function: firstly, by inhibiting the activation of muscle contraction which is due possibly to a reduction in the release of Ca2+ from the sarcoplasmic reticulum and a reduction in the affinity of the myofilaments to Ca2+. Secondly, by inhibiting muscle relaxation which is thought to result from a disruption in actin-myosin corss-bridge separation and a reduction in the rate of Ca2+ removal from the myofibril cytoplasm. Thirdly, by inhibiting muscle glycolysis at the point of PFK. Finally, there is some evidence to suggest that the rate of muscle lactate efflux and/or the metabolic fate of lactate produced during high intensity exercise are different from normal after a period of dietary manipulation.

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Peeters, Mon Jef. "The effect of recovery strategies on high-intensity exercise performance and lactate clearance." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2735.

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PURPOSE: To compare the effects of recovery intensity on performance of a bicycle sprint task and blood La⁻ clearance. METHODS: On three separate days twelve trained male subjects (27.4 ± 3.9 yrs) performed three supramaximal exercise (SE) bouts at 120% of maximum aerobic power (MAP) for 60% of the time to exhaustion (TTE). Bouts were separated by 5 mm of passive recovery (PR), active recovery (AR) or combined active recovery (CAR). The third bout was followed by a 14 mm recovery. Recovery intensities were: PR (rest), AR at 50% of the workload difference between the individual anaerobic threshold (IAT) and the individual ventilatory threshold (IVT) below the IVT ( ₋50%ΔT), or CAR at the IAT workload for 5 mm and at the ₋50%ΔT workload for 9 mm. Five 10 s sprints were performed 2 mm post-recovery. Blood lactate (La⁻) concentration, power parameters (Peak Power (PP), Mean Power (MP), Fatigue Index (Fl), and Total Work (TW)), Heart Rate (HR), and Oxygen Uptake (VO₂) were compared using repeated-measures ANOVA. Pairwise comparisons and dependent T-tests were performed to analyze differences. RESULTS: Mean La⁻ values for AR and CAR were lower than PR (9.7 ± 3.5, 9.5 + 3.5, 11.7 + 3.6, respectively, p≤0.05). La⁻ was significantly lower with CAR versus PR at the 3rd, 6th, 9th, and 14th mm of recovery (p≤0.05). AR versus PR La⁻ was lower at the 3rd, 6th, 9th, and 14th min of recovery (p≤0.05). Mean MP was greater in the AR group compared to the PR group (800.1 ± 114.5 vs 782.2 ± 111.7 W, p≤0.05). TW during AR was greater than PR (p≤0.05) but not CAR (p≤0.05, 40003.3 ± 5110.2, 39108.3 ± 4852.9, 39335.8 ± 5022.6 J, respectively). CONCLUSIONS: AR and CAR both demonstrated improved La⁻ clearance when compared to PR, but differences in La⁻ clearance did not determine performance on the sprint task. AR resulted in more TW than PR and greater maintenance of power over the sprints.

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Murgatroyd, Scott Richard. "'Parameters determining the induction and recovery of high intensity exercise intolerance in man." Thesis, University of Leeds, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.521468.

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Toone, Rebecca. "Assessing the hormone response to high intensity exercise and identifying associations with performance." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675729.

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The aim of this programme of research was to add to the existing body of knowledge on the measurement of certain hormones in relation to exercise training, the response to high intensity training, and their potential influence on short-term performance. The initial studies demonstrated agreement between venous and capillary concentrations of an array of hormones, and agreement between venous and saliva concentrations of testosterone and cortisol following scaling of saliva concentrations, suggesting suitability of use in an applied exercise setting. In addition, to ensure accurate measurement of steroid hormone concentrations in saliva, it was shown that samples should be refrigerated immediately, transferred to a freezer within 24 h of collection, and analysed within 28 days. Assessment of the response to two exercise bouts of a different type within the same day indicated that it could be beneficial to perform resistance training in the afternoon preceded by interval exercise in the morning in order to stimulate a hormonal milieu that may be more conducive to stimulating muscle protein turnover. The robust increases seen in testosterone and cortisol following interval exercise performed in the morning in that study were also observed in the same cycling sprint interval protocol performed in females. In this study, the magnitude of change in DHT concentration was related to sprint cadence. In investigating the potential acute effects of hormones on performance, the penultimate study demonstrated a positive association between affect as an indicator mood and percentage testosterone concentration during high intensity cycling. Conversely, in the final study, no postactivation potentiation effect was observed to different exercise stimuli, thus no association was observed between hormone concentrations and strength and power performance. These data may suggest that the acute short-term effects of hormone concentrations on performance may be more related to mood and behaviour in the context of this research.

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Wilkins, Lisa Jacqueline. "The effect of graded and short-term, high-intensity exercise on expiratory muscle performance." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-03032009-040735/.

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Lipski, Marcin. "High-intensity interval eccentric cycling: Acute and chronic effects." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2018. https://ro.ecu.edu.au/theses/2104.

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Eccentric cycling training has been prescribed in continuous and low intensities protocols, based on concentric cycling parameters. While the lower metabolic demand of eccentric than concentric cycling is advantageous for clinical or ‘at-risk’ populations, it is a disadvantage for cardiovascular and pulmonary adaptations. High-intensity interval protocols may increase both, strength and endurance. Thus, this research project compared i) an incremental concentric and eccentric cycling test until exhaustion for the relationship between power output and physiological parameters <Study1>; ii) interval and continuous eccentric cycling protocols for oxygen consumption, perceived exertion and enjoyment <Study 2>; and iii) aerobic performance, muscle morphology and function after 8-week interval eccentric versus concentric cycling training <Study 3>. Study 1: Nine men and two women (20-48 y) performed an incremental concentric and eccentric cycling test. Peak power output (PPO) was 53% greater (PStudy 2:The same subjects as those of Study 1 performed continuous cycling at 60% of PPO for 20 min at 60 rpm, and 13.2 min at 90 rpm (CONT13@60%), 4 x 4 min intervals at 75% of PPO with 2 min rest, 12 x 1 min at 100% of PPO with 1 min rest and 10 x 1 min at 150% of PPO with 1 min rest (INT1x10@150%). Total VO2 was the largest (pStudy 3:Eighteen men (19-56 y) performed either eccentric (EC, n=9) or concentric cycling (CC, n=8) twice a week for 8 weeks on an isokinetic cycling ergometer. Intensity was matched for perceived effort, started at 30% and 45%, and increased to 36% and 70% of concentric sprint PPO (10s) for CC and EC, respectively, and progressively increased from 5 x 2 min with a 1-min rest to 7 x 2 min with 30-s rest. The magnitude of increases in quadriceps cross-sectional area, concentric sprint PPO, countermovement and squat jump was greater (P

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36

Vaughan, Robert H. (Robert Harris). "Physiologic and Hematologic Responses Resulting From High-Intensity Training Among Elite Female Middle- and Long-Distance Runners." Thesis, University of North Texas, 1989. https://digital.library.unt.edu/ark:/67531/metadc330610/.

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The problem addressed in this study is whether physiologic, hematologic, and performance parameters obtained during and after a long term program of anaerobic and aerobic exercise can be used as markers of chronic fatigue.

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Evans, Elizabeth Serex Battaglini Claudio L. "Cardiovascular and blood lactate responses to low, moderate, and high intensity aerobic exercise in breast cancer patients is exercise intensity a true reflection of perceived exertion? /." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2008. http://dc.lib.unc.edu/u?/etd,1840.

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Thesis (M.A.)--University of North Carolina at Chapel Hill, 2008. Title from electronic title page (viewed Dec. 11, 2008). "... in partial fulfillment for the degree of Master of Arts in the Department of Exercise and Sport Science Exercise Physiology." Discipline: Exercise and Sports Science; Department/School: Exercise and Sport Science.

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Guelfi, Kym Janese. "Glucoregulatory responses to intermittent high-intensity exercise in individuals with type 1 diabetes mellitus : insight into the risk of hypoglycaemia." University of Western Australia. School of Human Movement and Exercise Science, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0078.

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[Truncated abstract] Exercise is generally recommended for individuals with type 1 diabetes mellitus since it is associated with numerous physiological and psychological benefits. However, participation in exercise can also increase the risk of experiencing severe hypoglycaemia both during exercise and recovery. Unfortunately, existing guidelines to minimise the risk of exercise-induced hypoglycaemia are often general and fail to take into account that different precautions are required for exercise of varying type, duration and intensity. Specifically, there are no evidence-based guidelines for safe participation in intermittent high-intensity exercise (IHE), which characterises the activity patterns of most team and field sports, manual labour occupations and spontaneous play in children. This is because the response of blood glucose levels to this type of exercise is not known. Consequently, the purpose of this thesis was to investigate the glucoregulatory responses to IHE that replicates the high-intensity work-to-recovery ratios observed in intermittent sports in individuals with type 1 diabetes, in order to assess the associated risk of hypoglycaemia. The first study of this thesis examined the effect of the repeated bouts of high-intensity exercise that characterise IHE compared to remaining inactive, on blood glucose and glucoregulatory hormone levels in individuals with type 1 diabetes. Eight healthy individuals with type 1 diabetes were tested on two separate occasions during which either a 20 minute rest (CON) or an IHE protocol designed to simulate the activity patterns of team sports was performed (repeated 4 second sprints every 2 minutes). ... During the second hour of recovery, Ra and Rd returned to baseline following MOD, but remained elevated after IHE. These changes in Ra and Rd were consistent with a lower glucose infusion rate (GIR) during early recovery from IHE and a higher GIR after 2 hours of recovery compared to MOD. In conclusion, the repeated bouts of high-intensity exercise associated with IHE stimulate a more rapid and greater increment in Ra during exercise and attenuate glucose Rd during early recovery. These findings assist in explaining, in part, the previous observation that the risk of hypoglycaemia might be lower during IHE and early recovery compared to MOD. Overall, the findings of this thesis have implications for current recommendations aimed at managing blood glucose levels during and after exercise to avoid hypoglycaemia.

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Born, Stephanie Ann. "The Effect of Creatine Supplementation on Exercise Performance following a Short-term Low Carbohydrate Diet." University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo149340968232177.

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Stone, Michael H., Meg E. Stone, William A. Sands, Kyle C. Pierce, Robert U. Newton, G. Gregory Haff, and Jon Carlock. "Maximum Strength and Strength Training---A Relationship to Endurance?" Digital Commons @ East Tennessee State University, 2006. https://dc.etsu.edu/etsu-works/4615.

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Endurance can be defined as the ability to maintain or to repeat a given force or power output. The sport performance-endurance relationship is a multi-factorial concept. However, evidence indicates that maximum strength is a major component. Conceptually, endurance is a continuum. The literature indicates that (a) maximum strength is moderately to strongly related to endurance capabilities and associated factors, a relationship that is likely stronger for high intensity exercise endurance (HIEE) activities than for low intensity exercise endurance (LIEE); (b) strength training can increase both HIEE and LIEE, the effect being greater for HIEE; (c) the volume of strength training plays a role in endurance adaptation; and (d) mechanical specificity and training program variables also play a role in the degree of adaptation..

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Toma, Kumika. "Effects of High-Carbohydrate and Low-Fat Versus High-Protein and Low-Carbohydrate Diets on High-Intensity Aerobic Exercise." View abstract, 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3372362.

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Han, Dae Uk. "Feasibility Assessment of High-Intensity Interval Training in Adults Living with Severe Mental Illness." Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/23386.

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Background: Adults living with Severe mental illness (SMI) are at a high risk of cardiovascular disease. With the growing popularity for High-Intensity Interval Training (HIIT), some evidence suggests that there is potential to greatly reduce cardiovascular and metabolic risk factors and improve functional exercise outcomes in comparison to moderate-intensity continuous training (MICT). However, little research on HIIT has been done in SMI. Therefore, the aim of the study was to assess the feasibility of HIIT in adults living with SMI. A secondary aim was also proposed, to compare the effect of HIIT to a lifestyle intervention in relation to Cardiometabolic Risk Factor (CMRF) and functional exercise capacity. Method: Adults living with SMI, attending a service provided by the Collaborative Centre for Cardiometabolic Health in Psychosis (ccCHiP) were recruited to participate in one of two 10-week programs, during their visit. The programs offered were a HIIT (Intervention; 20-min HIIT session, three times per week) or a lifestyle program (Control; 30-min lifestyle education and 30-min circuit exercise program, once per week). Feasibility was assessed based on enrolment and withdrawal rates in each group. Lipid profile and 6-Minute Walk Test (6-MWT) were variables assessed for CMRF and functional exercise capacity, respectively. Result: 15 participants were recruited (Intervention = 11; Control = 4). A total of 4 participants withdrew from the study (Intervention = 3; Control = 1). No significant difference was found between the intervention and control for lipid profile and 6-MWT. Conclusion: Preliminary evidence suggests that HIIT may be a feasible program, based on the level of enrolment seen among adults with SMI.

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Mannion, Anne Frances. "Limiting factors to high intensity exercise : the role of intramuscular pH and skeletal muscle buffering." Thesis, University of Salford, 1990. http://usir.salford.ac.uk/26797/.

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Within the context of a metabolic model of fatigue, formulated from a review of the literature, a decrease in intramuscular pH was identified as a potential limiting factor to the performance of high intensity exercise (HIE). This suggested a role for skeletal muscle buffering (B) in retarding the intramuscular acidosis typically incurred during HIE. Previous studies on human muscle, were largely unable to confirm this role, partly due to the lack of a clearly defined and consistently utilised method of measurement of B. The validity of the procedures currently employed in the determination of B was therefore investigated, revealing that many of the individual differences in B, previously attributed physiological significance, may have originated from inappropriate methodology. In a cross-sectional examination of the vastus lateralis muscle of young, active individuals, low correlations (p<0.05) between the muscle carnosine concentration ([CAR]) and in the 'in vitro B' (Bvit) (r=0.30), and between either [CAR] or Bvit and the % type II fibre area were observed. An elevated Bvit was shown to be of importance in minimising the decrement in pH during HIE, but did not per se permit the accumulation of a higher muscle lactate concentration, or allow for an enhanced HIE performance; these factors were more dependent on the % type II fibre area. The muscle pH, following dynamic HIE was highly variable between individuals, and showed a significant (p<0.05) negative correlation with the % type II fibre area. 16 weeks of isokinetic training of the quadriceps resulted in significant improvements (p<0.05) in dynamic HIE performance with no concomitant improvements in [CAR] or Bvit. The data suggest that the muscle buffer value per se, is not a major limiting factor to HIE, and that rather, the glycolytic capacity and pH tolerance of the muscle may be the more important factors to consider.

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Sperlich, B., D. P. Born, K. Kaskinoro, K. K. Kalliokoski, and Marko Laaksonen. "Squeezing the Muscle : Compression Clothing and Muscle Metabolism during Recovery from High Intensity Exercise." Mittuniversitetet, Avdelningen för hälsovetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-18973.

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The purpose of this experiment was to investigate skeletal muscle blood flow and glucose uptake in m. biceps (BF) and m. quadriceps femoris (QF) 1) during recovery from high intensity cycle exercise, and 2) while wearing a compression short applying ~37 mmHg to the thigh muscles. Blood flow and glucose uptake were measured in the compressed and non-compressed leg of 6 healthy men by using positron emission tomography. At baseline blood flow in QF (P = 0.79) and BF (P = 0.90) did not differ between the compressed and the non-compressed leg. During recovery muscle blood flow was higher compared to baseline in both compressed (P<0.01) and non-compressed QF (P<0.001) but not in compressed (P = 0.41) and non-compressed BF (P = 0.05; effect size = 2.74). During recovery blood flow was lower in compressed QF (P<0.01) but not in BF (P = 0.26) compared to the non-compressed muscles. During baseline and recovery no differences in blood flow were detected between the superficial and deep parts of QF in both, compressed (baseline P = 0.79; recovery P = 0.68) and non-compressed leg (baseline P = 0.64; recovery P = 0.06). During recovery glucose uptake was higher in QF compared to BF in both conditions (P<0.01) with no difference between the compressed and non-compressed thigh. Glucose uptake was higher in the deep compared to the superficial parts of QF (compression leg P = 0.02). These results demonstrate that wearing compression shorts with ~37 mmHg of external pressure reduces blood flow both in the deep and superficial regions of muscle tissue during recovery from high intensity exercise but does not affect glucose uptake in BF and QF. © 2013 Sperlich et al. :doi 10.1371/journal.pone.0060923

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45

Mier, Nicole M. "Training effect of a high intensity interval training (HIIT) program using upper extremity exercise." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1527569.

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The purpose of this study was to investigate the effects of a high intensity interval training program (HIIT) using the upper extremities on peak oxygen uptake (VO2peak), peak heart rate (HRpeak), total time-to-fatigue (TTF), peak power output (PPO), rating of perceived exertion (RPE), and blood lactate concentrations (bLa). Results showed significant (p ≤ 0.05) improvements by the HIIT group in VO2peak, HRpeak, PPO, and TTF when compared to a continuous training (CT) group. Results of this study suggest that upper extremity HIIT appears to produce greater improvements in several physiological outcome measures when compared to CT and may be an effective way to improve cardiopulmonary fitness. Furthermore, a HIIT program using the upper extremities as little as 2 days per week appears to be a viable way to improve factors that contribute to cardiopulmonary fitness, muscular fitness, and performance, while being an efficient use of time.

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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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Travis, S. Kyle, and Jeremy A. Gentles. "Using Echo Intensity as a Monitoring Tool to Determine Training Adaptations and Recoverability In High-Level Weightlifters." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/etsu-works/5831.

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48

Martinez, Nicholas. "Perceptual Responses to High-Intensity Interval Training in Overweight and Sedentary Individuals." Thesis, University of South Florida, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1535545.

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Contemporary aerobic exercise guidelines comprised of continuous durations and higher intensities have been shown to be effective in the prevention and treatment of risk factors associated with obesity and cardiovascular disease (CVD). However, high-intensity interval training (HIIT) has recently been examined as an advantageous protocol for producing more favorable physiological and psychological benefits in comparison to traditional continuous exercise guidelines. The dual-mode model, which examines the dose response relationship between exercise intensity and affective valence, would suggest that exercise performed well above the ventilatory threshold (VT) in the severe domain should result in negative affective valence. Numerous investigations have confirmed the reliability of the dual-mode models ability to predict compromised affective valence in the presence of heavy to severe exercise intensities, but only a small amount of research has examined the efficacy of the dual-mode model during HIIT. However, no research to date has combined HIIT with the dual-mode model's efficacy to predict affective valence in target populations challenged by exercise adherence, such as overweight and sedentary individuals. Therefore, the purpose of this study was to examine the dual-mode model's reliability to predict affective valence for overweight and sedentary individuals performing HIIT. A total of 14 participants (7 male, 7 female) with a mean age of 23 ± 4 (range = 18-33) and mean BMI of 29 ± 3 (range = 25-33) completed the study. Each participant completed a ramp maximal exercise test to determine VT and peak power data, which allowed for specific exercise intensities of delta (DT) to be prescribed for experimental trials. Participants were low to moderate risk. The four experimental conditions were all matched for total work: 1) continuous at 10% DT (Continuous-Heavy - CH), 2) 24 × 30-second intervals at 60% DT (Interval-Severe 30 Second - IS30), 3) 12 × 60-second intervals at 60% DT (Interval-Severe 60 Second - IS60), 4) 6 × 120-second intervals at 60% DT (Interval-Severe 120 Second – IS120). The continuous exercise condition was 20 minutes in duration, whereas all interval exercise conditions were 24 minutes in duration. Results indicated that in-task perceptual responses defined, as affective valence and perceived enjoyment were overall more favorable during IS30 and IS60 in comparison to CH and IS120. IS30 was the only experimental condition in which affective valence did not decline significantly (p > 0.05). Ratings of perceived enjoyment were greater at all measured time points during IS60 (p < 0.05) in comparison to CH. The findings of this study suggest that HIIT comprised of 30 and or 60 seconds help to facilitate more favorable perceptual responses of affective valence and perceived enjoyment than continuous exercise and intervals of longer than 60 seconds duration.

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Smith, Michelle R. "Effects of Pre-exercise Muscle Glycogen Status on Muscle Phosphagens, Sarcoplasmic Reticulum Function, and Performance During Intermittent High Intensity Exercise." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/34813.

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Eight competitive cyclists performed two cycling trials, one following a high carbohydrate diet (H-CHO) and the other following a low carbohydrate diet (L-CHO). Trials consisted of repeated 60s maximal effort sprints to fatigue at a workload designed to elicit 125-135% VO2peak at 90rpm. Three min of recovery separated sprints. Muscle biopsies taken at rest (biopsy 1), 85% max interval rpm (biopsy 2), and 70% max interval rpm (biopsy 3) revealed a main effect of diet on muscle glycogen levels: 609 Â± 38 HCHO vs. 390 Â± 42 mmol/kgdw L-CHO at biopsy 1, 383 Â± 29 vs. 252 Â± 28 mmol/kgdw at biopsy 2, and 346 Â± 29 vs. 196 Â± 18 mmol/kgdw at biopsy 3 (p<0.01). Similar decreases in muscle glycogen (45%), creatine phosphate (CP) (35%), and sarcoplasmic reticulum (SR) Ca2+-uptake (56%) were shown in both trials from biopsy 1 to 3. SR Ca2+-release decreased by 53% in H-CHO subjects and 36% in L-CHO subjects. Total exercise time tended to be longer in H-CHO than L-CHO subjects (57.5 Â± 10 vs. 42.0 Â± .89min) (p=0.09). H-CHO subjects exercised significantly longer than L-CHO subjects from biopsy 2 to 3 (33.6 Â± 10 vs. 18 Â± 3.6min) (p< 0.05). Results suggest that fatigue from 40- 60min of intermittent 60s high intensity cycling intervals is associated with reductions in muscle glycogen, CP, and SR function, and that the latter part of performance is impaired by low muscle glycogen. These data do not support a relationship between muscle glycogen status and SR function in intermittent high intensity exercise. Master of Science

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Bonsu, Biggie. "The effect of high intensity interval training on the post-exercise hypotensive response in overweight/obese young women." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85809.

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Thesis (MScSportSc)--Stellenbosch University, 2013. ENGLISH ABSTRACT: There are extensive literature on the PEH response after acute and chronic aerobic and resistance exercise, as well as a few studies on concurrent and water exercise. However, there is comparatively little evidence that high intensity interval training (HIIT) elicits similar post exercise blood pressure reductions (PEH) compared to other types of exercise. Furthermore, it is difficult to quantify the magnitude of the hypotensive response following these exercises, due to variations in exercise protocols in terms of intensity and duration. Both these training variables are considered important determinants of the magnitude and duration of the PEH response. The current study determined the magnitude of the PEH response after an acute bout and six sessions of HIIT, and the effects after two weeks of detraining in overweight/obese young women. Twenty young women (aged 21 ± 2 years) volunteered for the study. All the subjects were normotensive (SBP: 119.2 ± 5.6 mmHg and DBP: 78.8 ± 4.1 mmHg). Subjects performed six sessions of HIIT within two weeks and detrained for two weeks. SBP, DBP, MAP and HR were monitored during seated recovery after exercise for 60 min to determine the change from resting values. The overall outcome showed that an acute HIIT session resulted in a reduction of 2.9 mmHg in SBP which approached near clinical significance, while six sessions of HIIT caused a clinically significant reduction of 5.3 mmHg; this response was almost totally reversed after detraining. There were no clinically significant reductions in DBP after the acute or six sessions of HIIT (1.7 and 2.7 mmHg, respectively). However, a clinically significant hypotensive response of 3.9 mmHg was sustained after detraining following the maximal exercise capacity test. MAP also reduced by a magnitude of 2.3 and 5.6 mmHg, respectively, after the acute bout and six sessions of HIIT, and detraining values were still 2.9 mmHg lower than resting values and approached near clinical significance. The results indicate that both an acute bout and six sessions of HIIT elicited a meaningful PEH response. However, the six sessions of HIIT caused a clinically significant reduction which was approximately twice the acute session. Likewise, detraining showed clinically significant effects in DBP and MAP, but SBP returned to near baseline values. This suggests that in only two weeks, the accumulated effects of six sessions of HIIT elicited a greater hypotensive response than after an acute session of HIIT. AFRIKAANSE OPSOMMING: Daar is omvattende literatuur oor die post-oefening hipotensie (POH) na afloop van akute en kroniese aërobiese en weerstandsoefeninge, asook enkele studies oor gelyktydige krag- en uithouvermoë- en wateroefeninge. Daar is egter relatief min bewyse dat hoë intensiteit interval oefening (HIIO) soortgelyke post-oefening afnames in bloeddruk (POH) in vergelyking met ander tipes oefening veroorsaak. Voorts is dit moeilik om die omvang van die hipotensiewe respons na afloop van oefening te kwantifiseer, hoofsaaklik as gevolg van die variasies in oefeningprotokolle in terme van intensiteit en tydsduur. Beide hierdie inoefeningveranderlikes word as belangrike determinante van die omvang en die tydsduur van die POH respons beskou. Die huidige studie het die omvang van die POH respons na ŉ akute sessie en ses sessies HIIO, en die gevolge na afloop van twee weke se nie-inoefening (“detraining”) by oorgewig/vetsugtige jong dames, bepaal. Twintig jong dames (ouderdom 21 ± 2 jaar) het vrywillig ingestem om aan die studie deel te neem. Al die deelnemers was normotensief (SBD: 119.2 ± 5.6 mmHg en DBD: 78.8 ± 4.1 mmHg). Die deelnemers het ses sessies HIIO binne twee weke voltooi en het daarna vir twee weke geen inoefeningsessies gehad nie. SBD, DBD, GAD en HS is tydens ŉ sittende herstelfase vir 60 minute gemonitor om die verandering vanaf rustende waardes te bepaal. Die algehele uitkoms toon dat ŉ akute HIIO sessie ŉ afname van 2.9 mmHg in SBD tot gevolg gehad het wat aan kliniese betekenisvolheid grens, terwyl ses sessies van HIIO ŉ klinies betekenisvolle afname van 5.3 mmHg veroorsaak het; hierdie respons wat bykans volledige omgekeerd na die twee weke met geen inoefening. DBD het geen kliniese betekenisvolle afname na afloop van die akute of ses sessies van HIIO getoon nie (1.7 en 2.7 mmHg, respektiewelik). ŉ Klinies betekenisvolle hipotensiewe respons van 3.9 mmHg is egter gevind na die geen inoefeningsperiodes. GAD het ook met ŉ omvang van 2.3 en 5.6 mmHg, respektiewelik, verminder na afloop van die akute sessie en ses sessies van HIIO. Die geen inoefening waardes was steeds 2.9 mmHg laer as die rustende waardes en het aan kliniese betekenisvolheid gegrens. Die resultate toon dat beide ŉ akute sessie en ses sessies van HIIO ŉ betekenisvolle POH respons ontlok het. Ses sessies van HIIO het egter ŉ klinies betekenisvolle afname, wat ongeveer twee keer soveel as die afname van die akute sessie was, veroorsaak. In dieselde lig het ŉ twee weke geen inoefeningsperiode steeds klinies betekenisvolle veranderinge in DBD en GAD getoon, maar SBD het tot naby aan die basislyn waardes teruggekeer. Hierdie resultate suggereer dat in slegs twee weke die geakkumuleerde effekte van ses sessies van HIIO ŉ groter hipotensiewe respons as na ŉ akute sessie van HIIO ontlok het.

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Dissertations / Theses on the topic 'High intensity exercise'

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