The effects of exercise intensity and duration on excess post-exercise oxygen consumption (EPOC) were examined. Eight males exercised in a thermoneutral environment at 60% of maximal aerobic power (V0₂ₘₐₓ) for 30 min and performed the same total work at 80% and 40% V0₂ₘₐₓ by varying exercise durations. In addition, 2 work bouts were performed at 60% VO₂ₘₐₓ for 90 and 60 min. A standardized meal was consumed 2 h post-exercise. Oxygen consumption (V0₂), respiratory exchange ratio (RER), rectal temperature (Tc) and heart rate (HR) were monitored on a control day and before, during and for 3 h following exercise. VO₂ was equivalent to control day values within 30 min post-exercise on each of the 5 d and no consistent relation between exercise condition and duration of EPOC was observed. When total post-exercise VO₂ was expressed relative to control values, differences were greatest during the first 30 min post-exercise. Total net caloric expenditure was small (32. 5-57.9 kcal) in all cases. RER tended to remain equivalent to control levels post-exercise, with intermittent elevations. Significant elevations in Tc were obtained until 60 to 150 min post-exercise. No significant exercise-related effects were noted for dietary induced thermogenesis or the cumulative effect of the 5 exercise bouts on resting metabolic rate. Although exercise over a wide range of intensities and durations resulted in a significant EPOC, in all cases it was of short duration and the total 3 h energy expenditure was small. Neither duration nor magnitude of EPOC was associated with post-exercise RER or Tc. / Thesis / Master of Science (MSc)

Cardiovascular diseases (CVD) are the leading cause of death worldwide and the atherosclerotic process that precedes CVD starts during childhood. Physical activity (PA), cardiorespiratory fitness (CRF) and exercise are well known as preventive strategies for CVD. One possible mechanism for such prevention is the role of PA, CRF and exercise on the arterial and autonomic systems. The aim of this thesis was to investigate using observational and experimental studies the role of PA, CRF and exercise on the autonomic and arterial systems of healthy adolescents. Chapter 4 systematically reviewed observational cross-sectional studies and provided level one evidence for a significant and positive association between resting parasympathetic function and moderate-to-vigorous PA in youth. Chapter 4 also indicated that gaps exist in the literature such as the associations between PA intensities, CRF and heart rate variability (HRV). These findings were furthered in Chapter 5 which showed that vigorous PA (VPA) and moderate PA (MPA) were positively related with HRV at rest and cardiac autonomic recovery following exercise in adolescents. In Chapter 6 a high-fat meal was used aiming to increase CVD risk in the postprandial state, and it was demonstrated that PA levels and CRF are not significantly associated with postprandial HRV and arterial stiffness in adolescents. Aiming to investigate possible associations between the vascular and autonomic system, measures of baroreflex sensitivity (BRS) were introduced. Chapter 7 showed that BRS and its autonomic and vascular components present a between-day coefficient of variation lower than 20% whilst within day coefficient of variations were lower than 34% in adolescents. In Chapter 8 acutely following high- and moderate-intensity interval exercise a decrease in blood pressure was observed concomitantly with decreases in BRS. This was mainly mediated by decreases in the autonomic modulation, and the duration of the decreases in blood pressure was higher following high-intensity interval exercise. Chapter 9 extended these findings by demonstrating that the changes in BRS following the ingestion of glucose was not altered by the high or moderate-intensity exercise performed before glucose ingestion. Chapter 10 showed that following four weeks of high-intensity exercise interval training no improvements were observed in BRS and its autonomic and vascular components at rest or acutely following exercise. Collectively, the present thesis contributes significantly to the literature by providing novel evidence in healthy adolescents on the role of PA intensities, CRF and exercise on the arterial and autonomic systems at rest, acutely following exercise and in the postprandial state. The results gathered in this thesis indicate potential of the autonomic and vascular function as targets of CVD risk reduction in youth.

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.

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.

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. / Education, Faculty of / Kinesiology, School of / Graduate

Eighteen untrained males [age: 23 +/- 0.6 yr (SEM)] were randomized into high intensity (HIT: above lactate threshold, LT), moderate intensity (LIT: below the LT) or no training (NT) groups. Subjects trained on a cycle ergometer 4 days.wk-1 for 6 wk with the power output held constant. Maximal cycle ergometry was performed before and after the training period to determine changes in power output and oxygen consumption (VO2) at the LT and peak exertion. Before training and after 1, 2, 4, and 6 wk, subjects performed high constant-load (HCL) cycling bouts to quantify training adaptations in the SC. Training was designed to keep total work equivalent between the HIT and LIT groups. Increases in power output and VO2 at LT and peak exercise after 6 wk were noted in the HIT and LIT groups in comparison to NT group (p<0.05). No differences were noted between HIT and LIT. Two-way repeated measures ANOVA revealed a significant trial*group interaction for adaptation in the SC (p<0.001). After 1wk of training, a significant reduction in the SC was noted for HIT [mean+/-SEM]: (pre-training (PT): 703 +/- 61 ml.min-1; 1 wk: 396 +/- 60 ml.min-1) (- 44% from PT). Further adaptation for the HIT was also noted at 4 wk: 202 +/- 45 ml.min-1 (-71% from PT). For LIT, a significant reduction was noted at 2 wk (PT: 588+/-76 ml.min-1; 2 wk: 374 +/- 50ml.min-1) (-36% from PT). Further adaptation for LIT group was noted at 6 wk (252 +/- 38 ml.min-1) (- 57% from PT). Adaptation in SC was not noted at any interval for NT. Temporal changes in blood lactate (r = 0.40) and ventilation (r = 0.72) were significantly correlated with the changes for SC over the 6 wk training period (p<0.05). In conclusion, it was demonstrated that training at supra-LT and sub-LT intensities produces similar improvement in VO2 and power output at peak exercise and in the LT, when total work output is controlled. However, training at supra-LT intensity promotes larger and faster adaptations in the SC than training at the sub-LT levels. / Ph. D.

The main aim of this research was to develop a greater understanding of the effects of prior moderate and intense exercise on sports-related performance. The research developed through five related studies that examined the effects of exercise on key aspects of sports performance. Each study was conducted in appropriate field-based settings, using protocols that have relevance to the chosen sports and performance tasks that display ecological validity. Three intensities were examined across each of the five studies; rest, moderate and intense exercise. The preliminary study explored the effects of moderate and intense exercise on soccer passing performance in collegiate level players (n = 20). Repeated measures ANOVA revealed a significant (p = 0.010) effect of prior exercise on passing performance. Following on from this investigation, the effects of prior exercise on basketball passing performance in expert (n = 10) and non-expert players (n = 10) was examined. A 3 x 2 mixed ANOVA revealed a highly significant exercise intensity effect (p  0.001) as well as a highly significant exercise intensity by level of expertise interaction (p = 0.010). No between-group differences were observed however. This study nevertheless revealed that the expert players maintain a better level of performance compared to non-expert players following moderate and high-intensity exercise conditions. The third study explored the effects of moderate and intense exercise on coincidence-anticipation timing in expert (n = 11) and non-expert (n = 9) Gaelic games players. The 3 x 2 mixed ANOVA revealed no overall exercise intensity effect (p > 0.05) but there was a significant exercise intensity by level of expertise interaction (p = 0.031). Highly significant between-group differences (p < 0.001) were found, with the expert players maintaining a higher level of anticipation following moderate and intense exercise conditions. Study four comprised a small-scale study (n = 12) examining the effects of moderate and intense exercise on attention using the Stroop Colour-Word Test. Repeated measures ANOVA revealed a significant (p = 0.030) effect of prior exercise on attention. This study identified that attention following moderate-intensity exercise is equivalent to that at rest. However, following intense exercise attention deteriorates to a level below that at rest. The final study examined the effects of exercise intensity on groundstroke accuracy in expert (n = 13) and non-expert (n = 17) tennis players and comprised the most ecologically valid design. A range of 3 x 2 mixed ANOVAs were conducted revealing highly significant (p < .001) main effects for exercise intensity as well as highly significant (p = 0.003) between-group effects. No exercise intensity by level of expertise interaction was found however. In general, the findings suggest that performance following moderate-intensity exercise is equivalent to that at rest. However, significant decrements in key aspects of sports-related performance were observed following intense exercise. The findings of this research indicate that the theories of arousal cannot by themselves account for the outcomes of this work and the relationship between exercise and arousal needs to be explored further. Future research is imperative employing ecologically valid protocols and sport-specific performance tasks. The ensuing results in this case will have much more application and relevance to trainers, coaches and players.

There is need for enhanced prevention and treatment methods to combat sedentary lifestyle, obesity, and chronic disease by investigating the impact of specific exercise modalities and dietary factors on human health. The purposes of this study were: 1) to assess self-selected and perceived exercise intensity during High-Intensity Functional Training (HIFT) between males and females and to determine variables that predict self-selected exercise intensity (%VO2max) and/or perceived intensity (RPE) and 2) to investigate the impact of obesity on skeletal muscle metabolism in response to lipid oversupply by analyzing the responses of genes linked with fatty acid oxidation and inflammation in lean and obese subjects. Males and females were recruited to complete a 15min HIFT circuit wearing a metabolic analyzer, reporting RPE during and after the exercise bout. Obese and lean females were recruited to provide skeletal muscle cell biopsies for harvesting cell cultures from which to measure change in gene expression after exposure to a high lipid treatment. The first study results demonstrate that females exercised at a significantly higher self-selected exercise intensity while also reporting a lower RPE (p < 0.05). The second study revealed differential gene expression response and pathway activation related to lipid metabolism and inflammation between the lean and obese. In conclusion, gender plays a significant role in the intensity self-selected and the RPE reported during HIFT, suggesting HIFT may be an optimal home-based modality for female clients. Additionally, the skeletal muscle metabolic and inflammatory gene expression of the lean and obese respond differently to a high fat exposure and may provide further evidence of mechanisms linking obesity to metabolic disease.

These studies investigated the impact of intensity and body temperature on performance and cardiovascular regulation during high intensity and prolonged exercise. In study 1, polyphenol antioxidant supplementation proved to have no effect on exercise performance and related variables (gross efficiency, perceived exertion, maximal power) during exercise in the heat. Furthermore, there were no differences between the cardiovascular or thermoregulatory responses between control and antioxidant treatments. Study 2 utilized an integrative approach to investigate a classic topic in exercise physiology, namely, is the cardiac output to oxygen consumption relationship linear across a wide range of exercise intensities? The slope of the CO vs. VO2 relationship was significantly reduced from 70 to 100% of VO2max when compared to the slope from 40 to 70% of VO2max (2.0 ± 0.4 vs. 4.4 ± 0.3 l/min, p = 0.025). This finding, in combination with the plateau and eventual reduction in stroke volume at high intensity exercise compared to moderate intensity exercise (146.0 ± 16.6 vs. 138.5 ± 14.9 ml/beat, p = 0.015), argues in favor of a cardiac limitation to high intensity exercise. This study also showed that the pattern of oxygen extraction at the whole body level (arterial venous O2 difference) and the muscle level (deoxygenated hemoglobin) is not similar and that muscle specific differences exist regarding oxygen extraction. Study 3 determined that hyperthermia (elevation of skin temperature by 4.3°C and core temperature by 0.8°C) did not reduce SV independent of the increase in HR. Even under conditions of moderate hyperthermia the reduction in SV is due to the increase in HR and temporally unrelated to increases in cutaneous blood flow. In summary, antioxidant supplementation had no effect on performance, cardiovascular, or thermoregulatory responses to exercise in the heat in well trained subjects. High intensity exercise is associated with a reduced rate of increase in the CO vs. VO2 relationship. Finally, hyperthermia does not reduce SV during exercise when HR is maintained at normal levels. / text

Philosophiae Doctor - PhD (Physiotherapy) / Stroke is a debilitating medical and neurological condition. It is the leading cause of adult disability worldwide. Disability from stroke covers the three key classifications of the WHO-ICF framework on human function centred on health and health related issues, implying that the disability in stroke involve structural and activity limitations to participation restriction. Rehabilitation remains the hallmark of managing the plethora of neurological deficits accompanying stroke. Currently, the key advocacy in neuroscientific studies for stroke rehabilitation is that therapy should be directed towards task specificity. Task Specific Training most recently, the form of Circuit Class Therapy and the intensity of multiple repetition of the task has been identified as physiological mechanisms behind sustained motor learning following stroke.Circuit Class Therapy (CCT) is a form of Task Specific Training (TST) that involves the practice of structuring tasks in a circuit or series of workstations. It offers the patient the ability to practice multiple tasks in a conducive environmental because of its three key features of utilisation of different workstations that allow people to practice intensively in a meaningful and progressive way to suit their respective needs; the efficient utilisation of therapists'/trainees' time; and the group dynamics such as peer support and social support. Although these features are attainable following CCT challenges remain in selecting the most efficient intensity that could produce these benefits in stroke survivors. This study investigated the effectiveness of differing intensities of CCT in the rehabilitation of stroke survivors using the ICF framework to guide patients� response assessments after training.