The purpose of this study was to investigate the relationships between the arm joint angle at contact-release with peak velocity in experienced cerebral palsied athletes during wheelchair propulsion. The subjects (n = 5) exercised for a few minutes to familiarize themselves with the roller set up. After practice, each subject was asked to push the wheelchair as fast as possible up to 10 seconds. A tach-generator was attached to the core of the roller and interfaced to a computer via an eight bit A/D converter. The sampling rate of the roller speed was 200Hz. One video camera operating at 30 frames per second, and posisioned 7 m from the roller side was used. The data were analyzed for shoulder, elbow, and wrist angles with the Peak Performance program in I.B.M. compatible computer. Subjects' peak velocities were 8.85, 4.49, 4.19, 3.66, and 4.09 m/s, and the mean percent of contact and release times were 32.8% vs 67.2%. Shoulder, elbow, and wrist contact angles were not statisticaly in this study. Results indicate that contact-release angle on hand-handrim was effected for peak velocity. Also there was no significantrelationship between speed and cycle time.Key WordsRacing wheelchair, cerebral palsy, Peak velocity, Propulsion, Joint angle. / School of Physical Education

The purpose was to describe the physiological response and nutritional consumption of one athlete competing in the RAAM. The 1999 RAAM covered 4727 kilometers from Irvine, CA. to Savannah, GA. The subject was a 36 year-old male elite triathlete with 12 years of training experience. VO2max was 4.32 L/min. Prior to RAAM, cycling economy was measured at 100 and 150 watts. During RAAM, the following measurements were continuously recorded: heart rate, power output, nutritional intake, and body mass. Power output was recorded using a hub dynamometer (4 strain gauges, PowerTap). The subject completed RAAM in 10.1 days and spent 18.6 h/day cycling. Mean cycling values for power output, mechanical energy and heart rate were: 97 watts, 6676 kjoules and 99 b/min. Daily cycling energy expenditure was 7,946 +/- 1435 kcal/day. Energy intake averaged 6,812 +/- 914 kcal/day with 67% CHO, 24% fat, and 9% protein. Body mass decreased by 2.5 kg and percent fat decreased from 9.2% to 7.1%.

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Recent research has highlighted that information-movement couplings are unique to the constraints of the task, environment and performer. This recent research implies that skills should be developed in practice environments that are reflective of those found in competition. Representative environments should also allow the performer to attune to specifying information essential for success of a skill. However, in water polo, shooting practice is often conducted without the presence of a goalkeeper or defender. The aim of this study was to determine the effect of game-specific task constraints on the ball speed, accuracy and technique of the water polo shot. Ten male competitive level water polo players performed a total of forty shots comprising ten shots in each of four conditions from the 4m-penalty line. Conditions included all combinations of goalkeeper and defender (absent or present). Three Sony mini-digital cameras (50Hz) were placed perpendicular to the movement, giving rear, overhead and a right sagittal view. Ball speed was measured using a Radar-gun (Stalker Pro, USA). For each condition, means and standard deviations were determined for all outcome measures (shooting accuracy and ball speed) and technique variables. A repeated measures ANOVA was used to determine the effect (p<0.05) of the goalkeeper and defender individually as well as in combination on the dependent variables. Cohen's effect sizes were also used to determine the magnitude of the difference between conditions. The presence of a defender resulted in a significant increase in lateral trunk flexion at ball release, decreased the duration of the shot and selected swing sub-phases (i.e. pick-up to top of back swing time) and significantly altered the placement of the ball in the goal. When the goalkeeper only was present, this resulted in decreases in total shot time and pick-up to top of back swing time and significantly altered the placement of the ball in the goal. The presence of the defender and goalkeeper in combination brought about a moderate effect, decreasing the ball speed, significantly decreasing the success of the shots, scores achieved and significantly altering the placement of shots. Forward swing distance and selected swing sub-phases (i.e. total shot time, pick-up to top of back swing time, forward swing start to midway and forward swing start to release) were also significantly decreased in the presence of the defender and goalkeeper. These findings highlight the importance of maintaining appropriate task constraints during water polo shooting practice. In effect the removal of the defender and goalkeeper leads to the development of inappropriate information-movement couplings. Specifically, the presence of the defender and/or goalkeeper lead to reductions in the durations of selected swing sub phases, resulting in changes in the relative coordination and timing of the water polo shot. These findings indicate that in order to facilitate the development of this specific shooting skill, coaches should structure practice to replicate the perceptual information available during competition.

Background: Very few studies have examined the demands of prolonged batting on physical, psychophysical and performance responses. Objective: The purpose of this study was therefore to determine the physiological and perceptual responses of batsmen scoring a simulated One Day International century. Furthermore, the impact that these responses had on batting performance were also measured. Methods: Seventeen male cricketers currently playing for Rhodes University or the country districts side, performed a simulated bating innings (BATEX©), typical of scoring a One Day international century. The BATEX© protocol consisted of six, five over stages (21 minutes each), with each stage matched to a specific phase of play where batsmen were encouraged to bat with the mindset of that phase. During stages one, three and five players ran at a “self-selected cruise pace” whereas during stages two, four and six players were required to run at maximum speed. At set intervals, selected physiological, perceptual and performance measures were recorded. Results: Most physiological responses increased and decreased accordingly with the low and high intensity stages with the exception of respiratory exchange ratio and core temperature responses. Mean physiological responses however, showed a progressive rise over time. Central ratings of perceived exertion increased as a function of intensity and duration. Sprint times got slower as the protocol progressed, while accuracy (impact accuracy) improved significantly (p<0.05) after stage one and then stabilised for the remainder of the protocol. Conclusion: The simulated batting protocol significantly impacted the physiological and perceptual responses over time. This was due to both the intensity and the duration of the work-bout. Furthermore, the increased physiological load placed on the batsmen significantly impacted the physical performance of the batsmen. An increase in sprint times (players getting slower) towards the end of the protocol may indicate the presence of physical fatigue. This physical fatigue did not however seem to impact the batsmen cognitively as accuracy improved after the first stage and then remained constant over time.

To enhance understanding of recovery and preparation in rugby union, the aim of this thesis was to examine the impact of competition on key parameters and investigate factors which may influence the recovery process from competition and training. The findings of study one demonstrate that movement patterns and thus the physiological demands of match-play vary considerably between different positional groups. Additionally, study two demonstrates that the movement characteristics which determine the extent of muscle damage post-match are position specific, and that movement characteristics may be used to prospectively tailor individual recovery and manage subsequent training. Recovery patterns may also be influenced by factors not associated with match-play such as sleep, which has important physiological and psychological restorative effects. The findings of study three suggest that sleep patterns may vary considerably within a squad with many players presenting evidence of sleep disruption, particularly post-match which may be detrimental to recovery. Recovery following exercise may also be modulated by the application of post-exercise recovery strategies such as cold water immersion. However, study four demonstrates that cold water immersion may impede adaptation to strength training in rugby union players. When no recovery intervention was administered during a five week pre-season period, isometric mid-thigh pull peak force and relative peak force significantly increased by 5.4 +/- 4.7 and 5.8 +/- 5.4% respectively. However when individuals were immersed in cold water post-training there were no significant changes in strength during the training period. These findings may have great implications for strength training, particularly during periods of physical development. The findings of the thesis have furthered understanding of the characteristics of performance and identified several factors which influence recovery from training and competition. This in turn may be used to inform best practice procedures in attempt to 'optimise' preparation and recovery in rugby union.

The purpose of this study was to examine the effects of event order on a cycling(C)/running(R) or R/C biathlon. Eight experienced male biathlete/triathletes with a mean age of 24.9 + 4.6 yr formed the sample of the study. Results show no significant interaction effects on oxygen consumption peak, oxygen consumption during steady-state, ventilation, and heart rate when C/R or R/C are performed at 70% oxygen consumption peak for subsequent R and C respectively. These results seem to indicate that the biathlete/triathlete is efficient in both C and R to the extent that event order does not significantly interact with metabolic response in submaximal cycling and running.

In order to test the effect of artificially induced alkalosis and acidosis on the appearance of blood lactate and work production, six well-trained oarsmen (age= 23.8 ±2.5 wt = 82.0 ±7.5kg.) were tested on three separate occasions after ingestion of 0.3 gm/kg body wt. NH4C1 (acidosis) , NaHC03 (alkalosis) or a placebo (control). Blood was taken from a forearm vein immediately prior to exercise for determination of pH and bicarbonate (HC03). One hour following the ingestion period, subjects rowed on a stationary ergometer at a pre-determined sub-maximal rate for 4 minutes, then underwent an immediate transition to a maximal effort for 2 minutes. Blood samples from an indwelling catheter placed in the cephalic vein were taken at rest and every 30 seconds throughout the 6 minute exercise test, and every 3 minutes during a 30 minute passive recovery period. Pre-exercise blood values demonstrated significant differences (p<0.01) in pH and HC03 in all three conditions. Work outputs were unchanged in the submaximal test and in the maximal test (p>0.05), although a trend toward decreased production was evident in the acidotic condition. Analysis of exercise blood samples using ANOVA with repeated measures revealed that the linear increase in blood lactate concentration([BLA]) during control was significantly greater than acidosis (p<0.01), although [BLa] during alkalosis were consistently elevated above control there was no significant difference in the linear trend (p>0.05). During recovery, there was no significant difference in the rate of lactate disappearance amongst the three conditions. It was concluded that under this protocol artificial manipulation of the acid-base status of the blood does not significantly influence work production despite significantly reduced [BLa] during acidosis. The inability of these pH changes to alter exercise performance emphasizes the relative importance of the intracellular and the extracellular buffer systems in well trained athletes. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate