The purpose of this study was to identify the biomechanical factors limiting distance and the jump technique in the maximum effort standing long jump. The limiting factors and jump technique were identified through an analysis of the relationship between patterns of joint powers in the propulsion phase of the standing long jump and maximum isokinetic strength of the lower limb. The participants were 11 male athletes specializing in different events. Isokinetic strength of the extensor muscles at the ankle (30 and 90 deg/s), knee (60 and 180 deg/s), and hip (60 and 180 deg/s) joints was evaluated by dynamometry. Joint powers in the propulsion phase of standing long jump were calculated by inversed dynamics methods using digitized two-dimensional coordinate data (50 Hz) and ground reaction force data (500 Hz). Pearson's product-moment correlation analyses were used to assess the relationships between jump distance, joint powers over the propulsion phase, and isokinetic strength of the lower limb joints. The results indicated the following.
1. The magnitude of the body center of mass velocity and whole body mechanical energy at toe-off were correlated with jump distance (velocity: r=0.857, p<0.01, energy: r=0.926, p<0.01).
2. Peak powers at the knee and hip joints over the propulsion phase, normalized to body mass, were correlated with jump distance (knee: r=0.767, p<0.01, hip: r=0.723, p<0.05).
3. Isokinetic extensor strength at the ankle, knee and hip joints, normalized to body mass, did not correlate with peak power at the corresponding joint over the propulsion phase. Also, only knee extensor strength at 60 deg/s was correlated with jump distance (r=0.652, p<0.05).
4. Knee extension torque at maximum knee flexion, which is used as an index of countermovement, was correlated with jump distance (r=0.836, p<0.01) and peak knee power (r=0.765, p<0.01). In one participant who had the highest ratio of peak powers over the propulsion phase to isokinetic strength, knee extensor power was enhanced by increasing the knee extension torque with countermovement and coupling of the arm swing to knee extension during the propulsion phase.
Therefore, although the jump distance depended on the lower limb joint powers over the propulsion phase, the power was not directly modulated by isokinetic strength. This phenomenon might be derived from strategies that enhanced lower limb power with countermovement and coupling of the arm swing to lower limb motion.
