The Influence of Gender and Age on Hamstring Muscle Length in Healthy Adults

STUDY DESIGN: Cross-sectional descriptive study. OBJECTIVES: To examine the factors of gender and age, stratified by 10-year increments, on hamstring muscle length (HML) as measured by passive straight-leg raise (PSLR) and popliteal angle (PA). BACKGROUND: Differences in HML between men and women have not been examined for a large group of healthy adults over a wide range of ages. The usefulness of these data is to provide some typical values of HML for future reference. METHODS AND MEASURES: Two hundred fourteen adults (108 women, 106 men; age range, 20-79 years) with no known history of hip or knee joint disease and no history of recent hamstring strain participated in the study. PSLR (trunk-thigh angle) and PA (thigh-leg angle) were estimated with a goniometer. A 2-way analysis of variance (ANOVA) was used to analyze the effects of 2 independent variables (gender and age) on 2 dependent variables (PSLR and PA). Statistical significance was established at alpha<.05. RESULTS: HML differed significantly (P<.001) between genders for both methods of measurement, with females demonstrating greater flexibility than their male counterparts. The difference between genders was 8 degrees for PSLR and 11 degrees for PA. HML was not influenced by age. CONCLUSIONS: This study provides physical therapists with typical values of HML in healthy men and women.