The relationship between open and closed kinetic chain strength of the lower limb and jumping performance.

Closed kinetic chain (CKC) exercise has become popular in rehabilitation partly due to the belief that it is more closely related to function than open kinetic chain (OKC) resistance. This study's purpose was to investigate the relationship between OKC and CKC strength of the lower limb extensors and functional performance. Twenty uninjured female subjects performed isotonic strength tests for the knee extensors in OKC and for the hip, knee, and ankle extensors in the squat exercise (CKC). Vertical and standing long jump performance was assessed using an optoelectric motion analysis system. Pearson product-moment correlation analysis showed that CKC strength scores were correlated with vertical jump performance (r = 0.722, p = 0.002) and standing long jump performance (r = 0.650, p = 0.005). Open kinetic chain strength demonstrated minimal correlation with vertical jump (r = 0.097) and standing long jump performance (r = 0.070). We conclude that lower limb extensor CKC muscle strength is more highly related to jumping performance than knee extensor OKC strength, but further research is needed to assess possible differences in training effectiveness for these two regimes.