Abstract
BACKGROUND:
The effects of stretch-shortening cycle (SSC) training are well-described in the literature but the mechanism of how it changes the characteristics of the SSC moment-time curve and contraction velocity is unknown.
OBJECTIVE:
The purpose of the present study was to investigate the adaptation mechanisms of the knee extensor contractile properties in response to a short-term unilateral SSC exercise training.
METHODS:
Twenty-four subjects (22.9 ± 2.4 years) were randomised to an experimental or control group. A custom-built dynamometer was used to test the mechanical properties of the quadriceps muscle. Each subject participated in the pre-, and post-test session. Subjects in the experimental group participated in nine training sessions and performed maximal voluntary stretch-shortening cycle contractions on the dynamometer. Changes in the knee extensor contractile properties were measured from an SSC curve.
RESULTS:
Multivariate analysis of variance (MANOVA) revealed a significant multivariate effect for the measured variables in relation to group assignment. SSC exercise training significantly changed concentric moment(M_{CC}, F_{1,22} = 96.2, p = 0.000), and contraction velocity(F_{1,22} = 125.6, p = 0.000) resulting in a 29.6% improvement in concentric peak angular velocity (ω). Stepwise multiple regression analysis showed that ω was significantly predicted only by M_{CC}(r = 0.751, p = 0.005).
CONCLUSIONS:
Short-term unilateral SSC exercise training modifies the characteristics of the SSC moment-time curve and contraction velocity through the mechanical adaptation of the knee extensor contractile properties.