Developing a Practical Application of the Isometric Squat and Surface Electromyography

Abstract

Electromyography (EMG) is a research tool used in gait analysis, muscle coordination evaluation, clinical evaluation and sports techniques. Electromyography can provide an insight into neural adaptations, cross education effects, bilateral contraction deficiencies, and antagonist activity in exercise-related movements. While there are clear benefits to using EMG in exercise-related professions, accessibility, cost, and difficulty interpreting the data limit its use in strength and clinical settings. We propose a practical EMG assessment using the isometric squat to identify compensatory activation patterns and report early observations. Ten healthy participants were recruited. Participants performed a 2-min isometric handgrip protocol and an isometric squat protocol. The isometric handgrip was used to identify the expected EMG amplitude response solely due to fatigue. There was a significant increase in EMG amplitude after 2 min (p < 0.05), with the relative increase of 95% CI (1.4%; 27.4%). This indicates the relative increase in EMG amplitude expected if the only influence was fatigue in the 2-min protocol. In the isometric squat protocol, we identified a number of different muscle activation compensation strategies with relative EMG amplitude increases outside of this bandwidth. One subject demonstrated a quadricep compensation strategy with a 188% increase in activation, while reducing activation in both the hamstrings and lower back by 12%. Exercise professionals can use this information to design exercise programs specifically targeting the unloaded muscles during the isometric squat.