Lower Extremity Muscle Activation During Over Ground versus Treadmill Running

Abstract

Introduction: Treadmills employ a movable belt that creates a backward force not normally present during running. Discrepancies exist in the literature regarding differences in joint kinematics, kinetics and muscle activation during overground running (O) and treadmill running (T). The authors sought to identify lower extremity muscle activation differences between O and T in heel-strike runners while running at their preferred speed. The backward motion of the treadmill was hypothesized to decrease hamstring activation, which would in turn require a new forward propulsion mechanism to exist. Methods: Ten recreational runners volunteered for the study. Active surface electrodes (were placed on the following muscles of the right lower extremity: Rectus femoris, Semitendinosus, Biceps femoris, Tibialis anterior, Soleus, Gastrocnemius, Gluteus maximus and Gluteus medius. Participants then underwent a five-minute jogging warm-up on a treadmill at their own preferred pace. Maximum voluntary isometric contractions (MVICs) were performed for each of the eight muscles in order to normalized the measurements. Muscle activation data were collected and analyzed for O and T with participants running at their preferred pace. Paired t-tests were performed to determine differences in muscle activation between O and T running for each of the eight muscles. The level of significance was set at 5%. Results and discussion: No significant differences were observed between O and T running for each of the eight muscles tested. Individual muscle activity was similar between O and T with the soleus exhibiting the highest activity and the rectus femoris demonstrating the lowest for both scenarios. Support for the hypothesis was not observed, as the average muscle activation patterns between the two running conditions were similar for each of the eight lower extremity muscles. These results are different from previous studies and may be due to the participants running at a self-selected speed or inability to analysis each phase of gait individually. Conclusion: Based solely on the average muscle activation of eight lower extremity muscles, the treadmill is an acceptable alternative to overground running in recreational runners.