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

BackgroundDeep 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.ObjectivesThe 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 MethodsA 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/cm²). 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.ResultsDuring deep squatting with heel elevation, rectus femoris showed a statistically significant increase in EMG activity compared to foot flat in the ground (<i>p</i>-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).ConclusionThese findings suggest that elevated heel during deep squatting-standing movement enhances the rectus femoris muscle activity and lower back safety.