The reliability of anaerobic threshold and the validity of its use as an index of circulorespiratory endurance and performance capacity were investigated using coefficients of correlation and mean scores. Reliability was determined for anaerobic threshold prediction using nonlinear changes in the V̇e exercise intensity curve and for indices associated with anaerobic threshold. The validity of anaerobic threshold was established through comparison of indices related to recognized trials of functional capacity and endurance performance. Significant coefficients of reliability were produced for predicting AT from nonlinear V̇e responses. In addition, respiratory indices associated with anaerobic threshold were also found to be reliable measures of function. The validity of anaerobic threshold indices was specifically related to functional measures described by performance capacity measurements. There was no evidence to suggest that anaerobic threshold represented measures of functional capacity. It was concluded that an aerobic threshold represented a reliable measure of optimum aerobic utilization which closely followed functional measures associated with performance capacity. From results, several implications were posed for the use of anaerobic threshold. First, anaerobic threshold appeared to identify the metabolic components of exercise. Second, its use reflected a functional measure of optimum aerobic utilization. Third, it reflected exercise demand that was less strenuous resulting in fewer physiological and psychological limitations. Fourth, it implied that performance could be evaluated with respect to aerobic/anaerobic functions. A description of the investigation and the comparisons used for the determination of anaerobic threshold reliability and validity are included. / Master of Science

Data were collected from the initial symptom-limited maximal exercise tests of 161 patients without. diagnosed coronary heart disease (CHD). Subjects were grouped according to their systolic (SBP) and diastolic (DBP) blood pressure changes between the final two stages of exercise. / Master of Science

Two groups of horses were each fed either a control diet of ground hay and concentrates (4 horses), or a Similar diet with 10% added fat after undergoing a baseline Standard Exercise Test (SET). The SET was a stepwise, incremental test to exhaustion on an equine treadmill set at a 6% slope. Resting and working heartrates and rectal temperatures were monitored, and venous blood was collected at rest, and every 3 minutes during exercise, just prior to each speed change. Blood was analyzed for pH, hemoglobin, and pCO₂, and base excess and plasma bicarbonate levels were calculated using nomogram equations. Plasma samples were analyzed for albumin at each step, and for sodium, potassium, chloride, and lactate at rest and exhaustion only. The plasma SID was calculated at rest and exhaustion by the following equation: ([Na⁺] + [K⁺]) - ([Cl⁻] + [Lactate]) The SET was performed after 16 days of interval training, and once more after another 16 days of interval training. Differences over time during exercise were found: heartrate, lactate, and potassium increased (p<.001), and hemoglobin increased (P<.01). Decreases were found in PH, pCO₂, bicarbonate concentration, base excess, and chloride (p<.001). Training effects were found in resting and working heartrates, pCO₂, bicarbonate concentration, and base excess, which all decreased during exercise with training. Hemoglobin increased during exercise with training. There were treatment * SET interactions for Strong Ion Difference, base excess, lactate concentration, pCO₂, and pH. There were no differences found between groups for any of the variables measured. Both groups showed improvements in fitness with training, and the fat group had a higher level of plasma lactate by SET 3. These results suggest that a high fat diet combined with interval training may have some effects on plasma lactate, and that training alone can affect many variables. The results also give evidence to support the evaluation of SID during exercise in horses. / Master of Science

A growing body of research suggests that the respiratory system may be limited in its ability to meet the demands of increased ventilitory work. This is supported by studies reporting altered contractile properties of the diaphragm in response to increased ventilations. In order to determine if expiratory muscle function is affected by increased ventilitory demand, this study evaluated maximal expiratory pressure, PeMax, in response to two separate short-term, high-intensity exercise trials. Males (n=7) and females (n=5) not currently in active physical training underwent a VO₂ max test and a constant workload of 90% of VO₂ max. PeMax was measured at rest, immediately post exercise, and at one two and five minutes into recovery for both exercise trials. PeMax values were found to decrease 12% and 17% in response to graded and constant workload conditions respectively (P<.05), and this decline persisted throughout the five minute recovery. No Significant relationship was found between magnitude of decline in PeMax and VO₂ max or decline in PeMax and Ve max. These findings suggest that maximal graded exercise as well as exhaustive constant workload exercise corresponding to 90% of VO₂ max provide the ventilitory stimulus great enough to result in a decline in expiratory performance. / Master of Science

The current study aimed to examine the naturalistic relationship between physical activity and sleep by exploring frequency, type, and timing of exercise and their association with a variety of sleep variables (e.g., sleep onset latency, wake after sleep onset, sleep efficiency). Young adults (n = 1003) completed a variety of self-report questionnaires, including a week-long sleep diary and a survey of typical frequency, type, and timing of exercise completed in the past week. Increased frequency of physical activity was related to increased sleep efficiency (total sleep time/time in bed), decreased time in bed, and decreased time spent awake in bed in the morning. Greater amounts of exercise energy expenditure (i.e., metabolic equivalents) per week was related to increased sleep efficiency, and decreased time in bed and time spent awake in bed in the morning. After controlling for other factors, this relationship remained true only for time spent awake in bed in the morning. Early morning exercisers reported shorter total sleep time and time in bed than those who typically exercised at other times. No exercise differences were found between those who met the research diagnostic criteria for insomnia and those who did not. This study provides valuable information to help guide future experimental and intervention studies.

Call number: LD2668 .T4 1985 E44 / Master of Science

Call number: LD2668 .T4 1985 D37 / Master of Science

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.

This thesis examined four key areas considered to contribute to why the efficacy of sodium bicarbonate (NaHCO3) as an ergogenic aid remains equivocal. Firstly, familiarisation to and test re-test reliability of continuous constant load cycling to exhaustion (TLIM) at 110% peak power output (WPEAK) were investigated. Results indicated two trials are required before participants become fully familiarised and reliable data are obtained and that daily biological variation was 6 ± 11% (16 ± 28 s). The primary aim of study two was to determine the most appropriate exercise intensity for future studies in this thesis. A secondary aim was to elucidate why certain participants appear to respond to NaHCO3 ingestion and others do not (Price and Simons 2010, Saunders et al. 2011). Therefore, we evaluated cycling TLIM at 100%, 110% and 120% WPEAK in the same participants. NaHCO3 ingestion increased TLIM by 17% compared to placebo (PLA) at 100% WPEAK. This was due, at least in part, to attenuated localised ratings of perceived exertion (RPEL). No difference in group level data was observed between treatments at 110% WPEAK or 120% WPEAK although there was marked inter and intra individual variance. Thirdly, in order to evaluate the efficacy of NaHCO3 at a tissue level we examined the effects of NaHCO3 on dynamic isolated muscle performance undergoing cyclical length changes. Acute power output (PO) was on average 7.0% greater for NaHCO3 treated extensor digitorum longus (EDL) muscles and 3.6% greater for NaHCO3 treated soleus (SOL) muscles compared to control (CON). Increases in PO were due to greater force production throughout shortening. Treatment of EDL and SOL did not alter the pattern of fatigue at a group level although similar to study 2 there was marked inter individual variation. Finally, to determine the effects of training status we evaluated the effects of 6 weeks high-intensity cycling training on the efficacy of NaHCO3. Overall, pre-training TLIM was 10% greater with NaHCO3 compared to PLA with a benefit to harm odds ratio of 571. Overall, post-training TLIM was 6% greater with NaHCO3 compared to PLA with a benefit to harm odds ratio of 17. Similar to studies 2 and 3 individual variation was observed. Based on daily biological variation for TLIM of 6% (as determined in study 1) and a recommended benefit to harm odds ratio threshold of > 66, NaHCO3 improved TLIM before training only. We concluded that 6 weeks high-intensity cycling training reduces the effectiveness of NaHCO3 in previously non-cycling trained males. The change in efficacy is likely due to, at least in part, training induced changes in intracellular buffering capacity. In summary, NaHCO3 is an effective ergogenic aid for TLIM cycling at 100% WPEAK in non-cycling trained males. This is due, at least in part, to attenuated localised ratings of perceived exertion (RPEL). In contrast, 6-weeks high-intensity cycling training reduces the efficacy of NaHCO3 for TLIM cycling at 100% WPEAK in previously non-cycling trained males. The change in efficacy is likely due to, at least in part, training induced changes in intracellular buffering capacity. At a skeletal muscle level, NaHCO3 increases acute PO in both predominantly fast (EDL) and predominantly slow (SOL) twitch muscle fibres, due to greater force production throughout shortening.

Thesis (MScMedSc (Biomedical Sciences))--University of Stellenbosch, 2005. / The purpose of this study was to determine the physiological and kinanthropometric attributes, respiratory muscle strength, and core stability of successful endurance paddlers, and to investigate the associations of these characteristics with kayak endurance performance in the laboratory and the field. Twenty male competitive paddlers (age: 28 ± SD 7 years, height: 184 ± SD 7 cm and weight: 80 ± SD 7 kg) were categorised in two ability groups, Elite and Sub-Elite. Testing included kinanthropometric measurements, maximum aerobic capacity, pulmonary function, six core stability tests, a 30 min endurance performance test (EPT) on the K1 Ergo and a 10 km time trial (TT) on the water. Maximum inspiratory mouth pressure (MIP) was measured before and after the 30 min EPT on the K1 Ergo to assess respiratory muscle fatigue. The Elite paddlers demonstrated significantly greater values for sitting height (as a percentage of stature), relative VO2max, PPO, PPO/kg, MVV and MIP compared to the Sub-Elite paddlers (All P < 0.05). They also demonstrated a significantly greater average PO and average back stroke length during the 30 min K1 Ergo EPT (P < 0.05) and a significantly faster race time (44:10 ± 1:17 vs 47:34 ± 3:14 min:s) during the 10 km water TT (P < 0.05), compared to the Sub-Elite paddlers. The paddlers did not experience respiratory muscle fatigue (as determined by change in MIP) after the 30 min K1 Ergo EPT. Significant intraclass correlations coefficients of r = 0.81 for average PO (30 min K1 Ergo EPT), r = 0.76 for MIP, and r = 0.95 for 10 km performance time, revealed the high repeatability of these tests. Significant relationships were found between the two endurance performance tests (30 min K1 Ergo EPT and 10 km water TT, r = -0.64, P < 0.05) and between both tests and a number of kinanthropometric, physiological and respiratory muscle function parameters. Stepwise multiple regression analysis revealed that PPO and MVV predicted endurance performance (average PO) on the K1 Ergo (R2 = 0.75, SEE = 15 W), whereas relative VO2max and best MIP predicted 10 km performance time on the water (R2 = 0.64, SEE = 115 s). The results of this study suggest that superior maximum aerobic capacities and respiratory muscle function distinguish successful paddlers from less successful paddlers and may be used to predict kayak endurance performance in the laboratory as well as on the water. No respiratory muscle fatigue occurred during the 30 min K1 Ergo EPT, indicating that respiratory muscle fatigue may not be a limiting factor to 30 min kayak endurance performance. The core stability results demonstrated no relevance to kayak endurance performance.