Acute effects of static and dynamic stretching on hamstring eccentric isokinetic strength and unilateral hamstring to quadriceps strength ratios

The main purposes of this study were to investigate the acute effects of static and dynamic lower limb stretching routines: (a) on peak torque, total external work and joint angle at peak torque of the hamstrings during maximal eccentric isokinetic leg flexion; (b) on unilateral hamstring to quadriceps (H/Q) strength ratios; as well as (c) to determine whether static and dynamic routines elicit similar responses. A total of 49 active adults completed the following intervention protocols in a randomised order on separate days: (a) non-stretching (control condition), (b) static stretching, and (c) dynamic stretching. After the stretching or control intervention, eccentric isokinetic peak torque, the angle of peak torque and total external work were assessed with participants prone at 1.04 and 3.14 rad center dot s1. Unilateral strength ratios of the knee were also recorded. Measures were compared via a fully-within-groups factorial analysis of variance (ANOVA). There were no main effects for eccentric isokinetic peak torque, angle of peak torque, total external work and unilateral H/Q strength ratios. The results suggest that dynamic and static stretching has no influence on eccentric strength profile and unilateral H/Q strength ratios and hence both forms of stretching do not reduce these two primary risk factors for muscle injury.