Relationship Between Gluteus Medius Muscle Activity, Pelvic Motion, and Metabolic Energy in Running (P190)

Abstract

PURPOSE: To investigate the relationship between gluteus medius muscle (GM) activity, pelvic motion, and changes in metabolic energy demands while running. METHODS: Five healthy, female subjects (mean age 22.8 +/- 2.2) were obtained from a sample of convenience. Subjects were recreational runners who ran >= 5 miles per week (mean 28.0 miles +/- 15.2). Subjects were asked to run on a treadmill for 30 minutes at a self-selected speed (6.52 mph +/- 0.2). Muscle Activity - Surface electromyography (sEMG) data was collected on the GM at a rate of 1000 Hz (MyoSystem 1200(TM), Noraxon). Kinematics - Three-dimensional data oil pelvic position was sampled at a rate of 60 Hz using all electromagnetic kinematic tracking system (MotionMonitor(TM), Innovative Sports Training) with sensors (Polhemus Fastrak) secured over the posterior superior iliac spines. Metabolic Energy Oxygen consumption (VO2) was obtained through ventilatory expired gas analysis (SensorMedics, Inc., Yorba Linda, CA) during rest, exercise and five minutes into recovery. The change in VO2 between 25-30 minutes (average value) was determined (Delta VO2) as was the time constant of VO2 recovery kinetics. MatLab v 7.1 was used for kinematics analyses. A Pearson's Correlation was calculated using SPSS v 14.0; statistical significance was defined as p<0.05. RESULTS: Peak GM amplitude exhibited a positive trend with VO2 recovery kinetics (R-2=0.807) and the rate of change in pelvic drop (R-2=0.647). Pelvic drop and kinetics were significantly correlated (R-2=0.942). However, Delta VO2 was not correlated with peak GM activity, pelvic drop, or kinetics. CONCLUSION: VO2 recovery kinetics were not influenced by Delta VO2 rather by biomechanical factors. Subjects with increased pelvic drop exhibited increased GM activity, and these two variables led to increased kinetics. These findings suggest that increased pelvic motion during running results in metabolic inefficiency, and could therefore adversely affect running performance.