The effects of plyometric versus dynamic stabilization and balance training on lower extremity biomechanics.

BACKGROUND Neuromuscular training that includes both plyometric and dynamic stabilization/balance exercises alters movement biomechanics and reduces ACL injury risk in female athletes. The biomechanical effects of plyometric and balance training utilized separately are unknown. HYPOTHESIS A protocol that includes balance training without plyometric training will decrease coronal plane hip, knee, and ankle motions during landing, and plyometric training will not affect coronal plane measures. The corollary hypothesis was that plyometric and balance training effects on knee flexion are dependent on the movement task tested. STUDY DESIGN Controlled laboratory study. METHODS Eighteen high school female athletes participated in 18 training sessions during a 7-week period. The plyometric group (n = 8) performed maximum-effort jumping and cutting exercises, and the balance group (n = 10) used dynamic stabilization/ balance exercises during training. Lower extremity kinematics were measured during the drop vertical jump and the medial drop landing before and after training using 3D motion analysis techniques. RESULTS During the drop vertical jump, both plyometric and balance training reduced initial contact (P = .002), maximum hip adduction angle (P = .015), and maximum ankle eversion angle (P = .020). During the medial drop landing, both groups decreased initial contact (P = .002) and maximum knee abduction angle (P = .038). Plyometric training increased initial contact knee flexion (P = .047) and maximum knee flexion (P = .031) during the drop vertical jump, whereas the balance training increased maximum knee flexion (P = .005) during the medial drop landing. CONCLUSION Both plyometric and balance training can reduce lower extremity valgus measures. Plyometric training affects sagittal plane kinematics primarily during a drop vertical jump, whereas balance training affects sagittal plane kinematics during single-legged drop landing. CLINICAL RELEVANCE Both plyometric and dynamic stabilization/balance exercises should be included in injury-prevention protocols.