The aim of this study was to compare the kinetic and kinematic characteristics of plyometric drop-jump and pendulum exercises. Exercises were filmed (100 Hz) from the sagittal view and manually digitized; the data were smoothed and differentiated using cross-validated quintic splines. Ground reaction force data were sampled using a Kistler force platform sampling at 500 Hz. Differences between movement amplitudes and coordination strategies were assessed using t tests and conjugate cross-correlations. Pendulum exercises involved a greater range of motion at the ankle and knee but less motion at the hip joint than drop-jumps. Although different in absolute terms, the exercises used a similar coordination strategy. Drop-jumps resulted in greater peak vertical ground reaction forces than the pendulum exercises although the latter involved a greater net impulse. The similarity between the movement patterns for the two modes of exercise led to the conclusion that pendulum exercises offer a training stimulus similar to that of drop-jumps.
Neil E. Fowler and Adrian Lees
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.
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.