Purpose: The current study examined how different training affects the kinematics and applied moments at the knee during sporting maneuvers and the potential to reduce loading of the anterior cruciate ligament (ACL). The training programs were 1) machine weights, 2) free weights, 3) balance training, and 4) machine weights + balance training.
Methods: Fifty healthy male subjects were allocated either to a control group or to one of four 12-wk training programs. Subjects were tested before and after training, performing running and cutting maneuvers from which knee angle and applied knee moments were assessed. Data analyzed were peak applied flexion/extension, varus/valgus, and internal/external rotation moments, as well as knee flexion angles during specific phases of stance during the maneuvers.
Results: The balance training group decreased their peak valgus and peak internal rotation moments during weight acceptance in all maneuvers. This group also lowered their flexion moments during the sidestep to 60°. Free weights training induced increases in the internal rotation moment and decreases in knee flexion angle in the peak push-off phase of stance. Machine weights training elicited increases in the flexion moment and reduced peak valgus moments in weight acceptance. Machine weights + balance training resulted in no changes to the variables assessed.
Conclusions: Balance training produced reductions in peak valgus and internal rotation moments, which could lower ACL injury risk during sporting maneuvers. Strength training tended to increase the applied knee loading known to place strain on the ACL, with the free weights group also decreasing the amount of knee flexion. It is recommended that balance training be implemented because it may reduce the risk of ACL injury.
1School of Sport Science, Exercise and Health, University of Western Australia, Perth, AUSTRALIA; 2School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Perth, AUSTRALIA; and 3Department of Orthopaedics, Stanford University, Palo Alto, CA
Address for correspondence: David G. Lloyd, Ph.D., School of Sport Science, Exercise and Health, University of Western Australia, 35 Stirling Hwy. Crawley, WA 6009, Australia; E-mail: email@example.com.
Submitted for publication June 2009.
Accepted for publication December 2009.