English, K. L., Amonette, W. E., Babington, D. F., Johnston, L. J., Dupler, T. L., & Wise, D. D. (2003). Closed and open kinetic chain strength training does not reduce landing forces in female athletes. Medicine and Science in Sports and Exercise, 35(5), Supplement abstract 1465.

"Research has shown plyometric training can decrease landing forces and increase activity of the hamstring muscles when jumping and landing. Closed kinetic chain strength exercises for the lower extremities recruit both the quadriceps and hamstrings to stabilize the knee joint. When the foot is in contact with the ground, the hamstring muscles act to reduce stress on the ACL. Thus, a strong contraction of the hamstrings and a decrease in landing forces could diminish the likelihood of ACL injuries" (p. S265).

Female college volleyball players (N = 30) participated in a 6-week periodized training session consisting of either open kinetic chain or closed kinetic chain exercises. Factors associated with landing were measured.

All ground reaction forces and time of foot contact remained unchanged in both groups. Changes in EMG signals were observed.

Implication. Six weeks of strength training did not change landing forces or movement patterns in female volleyball players. Prevention against ACL injuries should not be expected from these forms of training.

Return to Table of Contents for this issue.