The effect of heel elevation on rectus femoris and thoracolumbar extensor EMG activity during deep squatting-standing movement

Abstract

Background Deep squatting-standing movement is a multi-joint movement used to develop neuromuscular control and strength in different rehabilitation settings. The elevated heel during deep squatting-standing movement showed little literature on studying its effect on the back and lower extremity muscles. Objectives The current study investigated the impact of the elevated heel during deep squatting-standing movement on the electromyography activities of the selected rectus femoris and thoracolumbar extensor muscles. Materials and Methods A quasi-experimental study with one group was conducted on two separate occasions (feet flat on the ground and with heel elevation using a 7 cm wedge) with twenty young active Saudi female university students (Age = 20.72 ± 1.34 years, BMI = 21.48 ± 2.29 kg/cm 2 ). The electromyography (EMG) activity of the rectus femoris and thoracolumbar muscles was measured using the Delsys Trigno TM wireless EMG System (Delsys Inc., USA) during deep squatting to standing movements. Results During deep squatting with heel elevation, rectus femoris showed a statistically significant increase in EMG activity compared to foot flat in the ground ( p -value < 0.05). Conversely, thoracolumbar extensors showed a statistically significant decrease in EMG activity compared to the foot flat in the ground without statistically significant changes in EMG activity between right and left thoracolumbar extensors (p-value > 0.05). Conclusion These findings suggest that elevated heel during deep squatting-standing movement enhances the rectus femoris muscle activity and lower back safety.