Abstract

The relationship between mechanical work, mechanical energy transfers, and running velocity was investigated in one female and five male long jumpers. Different submaximal and maximal jumpers were filmed with Locam camera set to operate at 100 frames x s. The mechanical energy curves were used to calculate the amount of energy transferred within body segments and between potential (PE) and kinetic (KE) energy. This was obtained by calculating the mechanical work in three different ways: Wn, which assumes no energy transfers, Wwb which assumes that energy can be transferred both within and between segments, and Ww which assumes PE/KE exchanges only. Mechanical work of the lower limb was calculated by integrating the joint moments with the angular velocities. The results indicated no statistically significant differences between maximal and submaximal jumps with regard to mechanical energy transfers ( from Wn) during ground contact. However, during the airborne phase between the last two contacts, transfers between PE and KE in the swinging leg and trunk were dependent on the jumping effort. The positive work of the hip joint during the take-off was found to have a significant positive correlation with tzhe length of the jump (r=.89, p<0.001). Large PE7KE transfers in the swinging leg and trunk support the importance of the correct timing of the swinging leg in the impact (eccentric) phase of the take-off contact, when a small reduction of the resultant velocity is desired. Verf.-Referat