The Gluteus Medius Activation in Female Indoor Track Runners is Asymmetrical and May be Related to Injury Risk

Abstract

Track runners train and compete solely in the counter clockwise direction around the track. These repetitive motions place track runners at risk of “over-use” injury, but strength differences place females at greater risk than males. This study was conducted to evaluate the asymmetry of gluteus medius muscle activation patterns in female runners as they run around the curves of an unbanked 200 m track. Wireless surface electromyography (EMG) sensors were adhered to the skin overlaying the gluteus medius. Participants’ muscle activation was recorded as they ran two 200 m trials at a pace of 5±0.5 m/s and walked 200 m at a chosen pace. Each participant’s EMG for the running strides was normalized to the average amplitude of their walking trials. There were significant increases in muscle activation of the outside (right) gluteus medius when athletes ran on the curves compared to the straightaways (359.1 percent of walking ±132.8 and 324.7±102.6 respectively, p=0.015). There was a trend for de- creases in muscle activation of the inside (left) gluteus medius when athletes ran on the curves compared to the straightaways (449.2 percent of walking ±136.1 and 469.4±132.6 and respec- tively, p=0.065). These data suggest that the gluteus medius abducted the outside (right) leg to contribute to the lateral forces necessary to run around the curve. The muscular demands for the two legs are different, and are consistent with observed injury patterns. This loading pattern and mechanism of injury may be useful for guiding training and rehabilitation strategies. KEY