The purpose of this study was to assess the energy demands of a 2,000 meter race simulation (RS) for national level oarswomen; as evaluated on a rowing ergometer (RE). A Progressive Intensity Test (P.I.T.) was also performed on the RE to further evaluate the RS. Six national level oarswomen (X values: age= 24.5 yrs., ht= 179 cm, wt= 75 kg), all current national team candidates (1988), participated in this investigation. A 6 1/2 minute tape recorded water race was used to execute a 2,000 meter RS on a Dr. Gjessing Ergorow ergometer. The tape recording was an actual race tape that was respliced to last exactly 6 1/2 minutes. Metabolic and respiratory exchange variables were continuously monitored by an open circuit method, utilizing a Beckman Metabolic Measurement Cart interfaced on-line with a Hewlitt Packard 3052A data acquisition system. The energy demands were calculated from metabolic variables, total oxygen cost and the analysis of excess post-exercise oxygen consumption (recovery V0₂).Results indicated a mean V0₂max. of 3.85 1.min⁻¹ , mean net V0₂ of 24.48 1 and a mean recovery V0₂ of 4.92 1. This represented the aerobic cost of the event at approximately 80% or 4/5ths of the total energy cost while the anaerobic contribution was approximately 20% of l/5th of the total energy cost. During the RS, V0₂ values rapidly increased to 90% of mean V0₂max. (3.85 l.min⁻¹) in the first two minutes. Mean max. VE (BTPS) RS value was 122.4 1.min⁻¹. VE plateaued after two minutes and remained around 90% of P.I.T. mean max. VE for the final 4 1/2 minutes. Mean max. excess C0₂ for RS was 19.81 ml.kg⁻¹.min⁻¹. The average maximal heart rate, as recorded in the RS was 192.8 bpm. The results of this study indicate the high aerobic demands and tremendous exercise intensity involved in the 2,000 meter RS. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

No description available.

No description available.

No description available.

No description available.

No description available.

This study describes bone mineral index (g/cm²) of the distal and mid forearm, spine and hip in gymnasts/weight trainers, and runners with varying menstrual status. 12 eumenorrheic gymnasts/weight trainers (EGW), 11 eumenorrheic runners (ERU), 8 oligomenorrheic gymnasts/weight trainers (OGW), 3 oligomenorrheic runners (ORU) 4 amenorrheic runners (ARU) and a eumenorrheic control group (EC) of 18 subjects were examined. Bone mineral index (BMI) was measured using single and dual photon absorptiometry. EGW had greater BMI than ARU and EC (spine, hip and distal and mid forearm) and ERU (femur and distal forearm). The ARU were not significantly lower in BMI than the ERU. The ARU were only significantly lower in BMI than the EC at the distal forearm. OGW were not significantly greater in BMI than ORU. The OGW had greater BMI than the ARU (spine, femur and distal forearm), ERU and EC (femur and distal forearm). These results show higher BMI in gymnasts/weight trainers, independent of menstrual status, than in runners and controls.

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.