Locomotion Laboratory in the Department of Integrative Physiology, University of Colorado at Boulder
Saturday 2:30-2:45, Ballroom C
Enlargement of the gluteus maximus (GMAX) was an important adaptation in the evolution of human locomotion, but the functional purpose of this enlargement is less certain. No single study has quantified GMAX activation across the range of locomotor gaits and speeds for the same subjects, thus comparing relative electromyography (EMG) amplitudes has not been possible. Therefore, we assessed the EMG activity of the gluteal muscles during walking, running, sprinting and climbing. We hypothesized that the inferior and superior GMAX would be most active during sprinting and climbing. To gain further insight into the contribution of the gluteal muscles during running, we measured muscle activity during walking and running with external devices that either increased the torso’s moment of inertia or the hip extensor torque, increasing or decreasing the need to control forward trunk pitch. We hypothesized that the superior GMAX EMG would be most active when the need for trunk pitch control was increased and vise versa. We found that GMAX activity was greatest in sprinting, similar in running and climbing, and least in walking. Further, only the inferior GMAX significantly increased in activity when forward trunk pitch increased. Our data suggests that the large size of the GMAX reflects its role during rapid and powerful movements such as sprinting and climbing and that the superior GMAX does not control forward trunk pitch. Although this study is not extensive enough to make any definitive evolutionary conclusions, it demonstrates that the GMAX plays an important role in numerous modes of locomotion.
This project was funded in part by the Undergrate Research Opportunities Program of the University of Colorado at Boulder.