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Pushing Economy and Propulsion Technique of Wheelchair Racers at Three Speeds

Victoria L. Goosey and Ian G. Campbell

Pushing economy and wheelchair propulsion technique were examined for 8 wheelchair racers on a motorized treadmill at 6.0, 6.5, and 7.0 m/s. Kinematic data for the sagittal view were collected by a video camera for two-dimensional analysis. Adaptations to speed changes occurred, initially by a decrease in cycle time and an increase in cycle rate, and later by an increase in the flexion of the elbow. At each speed there were large variations in pushing economy between individuals. The relationship between pushing economy and selected kinematic variables revealed that at 6.0, 6.5, and 7.0 m/s, economy was associated with (a) the lighter athletes (r = .89, .86, .83), (b) a greater range of elbow movement (r = -.85, -.65, -.63), and (c) a lower push rate (r = .73, .81, .63), respectively. Effects of lesion level and wheelchair design may be more important in explaining differences in pushing economy than differences in propulsion technique.

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Influence of Glucose Ingestion Prior to Prolonged Exercise on Selected Responses of Wheelchair Athletes

Owen Spendiff and Ian G. Campbell

Eight men with spinal cord injury ingested glucose (CHO) or placebo (PLA) 20-min prior to exercise. Participants performed arm crank ergometry for one-hour at 65% V̇O2peak, followed by a 20-min performance test in which athletes were asked to achieve their greatest possible distance. Physiological responses during the one-hour tests were similar between CHO and PLA trials. At the onset of exercise, the CHO trial blood glucose concentrations were higher than PLA (p < .05) but returned to resting values after 20-min exercise. Respiratory exchange ratio responses during the CHO trial were indicative of a higher rate of CHO oxidation (p < .05). A greater distance (km) was covered in the 20-min performance tests after CHO ingestion (p < .05). Results show preingestion of glucose improves endurance performance of wheelchair athletes.

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Influence of Timing of GlucoseDrink Ingestion on Selected Responsesof Wheelchair Athletes

Owen Spendiff and Ian G. Campbell

Seven athletes with low lesion paraplegia ingested a 7.6% 648ml glucose drink using two schedules of ingestion (4 × 162 ml per 20 min & 2 × 324 ml per 60 min) in a crossover design. Participants exercised at 65% peak oxygen uptake for one hour, followed by a 20-minute performance test. The cardiorespiratory responses during the one-hour tests were similar between trials. Plasma glucose concentrations significantly increased after ingestion and remained stable during the 162 trial, but reduced over time during the 324 trial. Free fatty acid concentrations increased for both trials but increased significantly more during the 324 trial. The results of this study suggest that the ingestion of glucose during exercise is the best strategy for wheelchair athletes competing in endurance events.

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A Kinematic Analysis of Wheelchair Propulsion Techniques in Senior Male, Senior Female, and Junior Male Athletes

Victoria L. Goosey, Neil E. Fowler, and Ian G. Campbell

The aim of the study was to examine and compare the propulsion techniques of senior male, senior female, and junior male athletes and to determine the relationship between the kinematic variables and performance. A two-dimensional video analysis was performed on the 800 m finals (n = 23) at the 1994 British Wheelchair National Track Championships. From this, the angle of lean, elbow angle, and the cycle dynamics were determined. The senior male athletes achieved a faster maximum velocity (7.3 ± 0.3 m.s-1) than that achieved by the senior female (5.9 ± 1.0 m.s1) and junior male athletes (6.0 ± 1.0 m.s-1), resulting in a greater distance covered during each push cycle. The kinematic analysis showed that the junior athletes adopted a 5° more upright position and spent less time in contact with the hand-rim (25%) than the senior athletes. A moderate correlation was found between cycle distance and performance time (r = -0.68; p < 0.01). In conclusion, this study suggests that there are kinematic differences between senior male, senior female, and junior male wheelchair athletes.

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Physiological Responses of Endurance-Trained Male Wheelchair Athletes to a 10-Kilometer Treadmill Time Trial

Ian G. Campbell, Clyde Williams, and Henryk K.A. Lakomy

The purpose was to examine selected physiological responses of endurance-trained male wheelchair athletes in different Paralympic racing classes (T2, n = 3; T3, n = 8; T4, n = 7) during a 10-km treadmill time trial (TM:10-km). Peak oxygen uptake (V̇O2 peak) was determined, and a TM:10-km was completed on a motorized treadmill. From this, % V̇O2peak utilized and the relationship between V̇O2peak and TM:10-km were established. During the TM:10-km, the following dependent variables were examined: propulsion speed, oxygen uptake, respiratory exchange ratio, and heart rate. The results showed athletes utilize a high % V̇O2peak (78.4 –13.6%) during the TM:10-km. There was a moderate correlation (r = -.57, p < .01) between VO2peak and TM:10-km. No physiological differences were found between the paraplegic racing classes (T3, T4), which suggests that there is some justification in amalgamating these racing classes for endurance events.

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The Relationship between Three-Dimensional Wheelchair Propulsion Techniques and Pushing Economy

Victoria L. Goosey, Ian G. Campbell, and Neil E. Fowler

Three-dimensional kinematic and physiological data were obtained from 18 wheelchair racers, to allow the relationship between pushing economy and kinematic variables at 4.70 m · s−1 (n = 18) and 6.58 m · s−1 (n = 12) to be examined. Large inter individual differences in wheelchair propulsion styles were present, which made it difficult to identify variables that were associated with pushing economy and indeed to distinguish key variables that were characteristic of an economical wheelchair racer. Furthermore, those variables associated with economy proved inconsistent across the two speeds. However, at both speeds a higher mechanical efficiency and lower push rate were associated with better economy (p < .05). It was also found that the timing parameters were important. In this respect most athletes tended to push through a similar push angle; however, push rate differed between individuals, suggesting that the magnitude and direction of the hand-rim forces may be important for determining economy of propulsion.