Lower extremity muscular flexibility in long distance runners.

Muscle tightness is often considered to be a predisposing factor in muscle injuries. The purpose of this study was to assess the muscle flexibility of the hamstrings, rectus femoris, iliopsoas, gastrocnemius, and soleus muscles in long distance runners. Range of motion measurements of five movements, including hip flexion with knee extended, hip extension with knee flexed, hip extension with knee extended, ankle dorsiflexion with knee extended, and ankle dorsiflexion with knee flexed, were evaluated to determine muscle tightness. Twenty runners and 20 nonrunners volunteered for the study. Each group consisted of 10 males and 10 females. The observed means were compared between runners and nonrunners, males and females, plus the dominant and nondominant leg using a three-way analysis of variance. The runners were found to have tighter hamstrings (p < .05), and soleus (p < .05) muscles than nonrunners. There was no significant difference in rectus femoris and iliopsoas muscle tightness in runners compared with nonrunners. In addition, the males had tighter hamstring muscles than the females in both runners and nonrunners (p < .05). The hamstring muscles of the dominant leg were tighter than the hamstrings of the nondominant leg in all subjects (p < .05). In conclusion, long distance runners appear to have posterior muscle tightness in the lower extremity.