Effect of stretch positions on hamstring muscle length, lumbar flexion range of motion, and lumbar curvature in healthy adults

Abstract

Hamstring stretching is a common practice in physical therapy to change not only hamstring muscle length (HML), but also lumbar flexion range of motion (LROM) or lumbar curvature (LC). Yet limited published research compares the effectiveness of two commonly used hamstring stretch positions, sitting and standing. The purposes of this study were to determine the effect of (1) stretch position on HML; and 2) HML on LROM and LC. Thirty-six participants (M=44.8 years, SD=17.1) with short HML (i.e., with shortness for men ≥45° and for women ≥24° of active knee flexion with 90° hip flexion) were measured for HML, LROM, and LC; randomly allocated to one of three groups: (1) hamstring stretching in sitting (SI); (2) standing (ST); or (3) no stretching (control); and remeasured after 4 weeks. Participants in the stretching groups performed two 30-second static stretches 4 days per week for 4 weeks. Multivariate analysis of covariance (MANCOVA) showed significance between the stretching groups and nonstretching group for HML only. Nonsignificance was shown for HML between the stretch positions (i.e., SI–active knee extension (AKE) and ST-AKE), indicating that both were equally effective for increasing HML. However, there was no change in LROM or in LC even though HML increased.