The joint kinetics of the take-off leg affecting stiffness characteristics during bounding: Comparison with the rebound jump

Abstract

  The present study attempted to develop a training model using the rebound jump (RJ) for improving stiffness during bounding (BD), focusing on joint kinetics. 17 male track and field athletes (sprinters, jumpers, and decathletes) performed the BD and RJ. Video images of their jumping motions in the sagittal plane (300 Hz) and their ground reaction force data (1,000 Hz) were recorded. Stiffness was calculated using the spring-mass model, and the joint extension and plantar flexion torques during the first half of the take-off phase and negative torque power of the 3 lower joints (ankle, knee, hip) were calculated. The foot angle at the moment of touchdown during BD was also calculated. The results were as follows:
1.  During BD and RJ, stiffness was correlated with the ankle joint torque during the first half of the take-off phase and the negative torque power about the ankle joint.
2.  The foot angle at the moment of touchdown during BD was correlated with stiffness, contact time, ankle joint torque during the first half of the take-off phase, and negative torque power of the ankle joint.
3.  Ankle joint torque and negative torque power about the ankle joint during the first half of the take-off phase in BD were correlated with those during RJ.
  These results suggest that stiffness during BD and RJ are affected by ankle joint kinetics. On the basis of these results, previous studies and sports training principles, plyometric training using the RJ may be useful for improving the stiffness in BD via ankle joint kinetics.