Surface Electromyography analysis of the free, Smith Machine and split squats performed by strength-trained males.

Squats recruit a large proportion of the body’s muscular system and provide the foundation for strength training programs for athletes. However, our understanding of electromyographical activity in variations of the high-bar back-squat, notably the split squat, is somehow limited. Therefore, this study aims to investigate surface electromyography (sEMG) activity in the free, Smith and split types of squat. A randomised sample of 10 healthy strength-trained males (age, 20.3 ± 0.5 years; height, 1.7 ± 0.6 m; mass, 78.1 ± 9.5 kg) performed 3 repetitions of each type of squat at 75% of their 1RM. A Noraxon EMG - Raxon system was used to collect peak EMG, RMS EMG, and iEMG for the eccentric and concentric phases of the squat. All sEMG data was normalised to the Smith squat. Two-way ANOVAs were used for type-of-squat and phase-of-squat (p ≤ 0.01). Statistically significant effects for type-of-squat were found for peak EMG and iEMG of the bicep femoris (BF), lateral gastrocnemius (LG) and tibialis anterior (TA) (0.001 ≤ p ≤ 0.003). Significant differences in phase-of-squat were found for peak EMG and RMS EMG of BF (p = 0.001). RMS EMG of the BF (p = 0.002) and LG (p = 0.001) showed significant differences regarding type-of-squat. Therefore, the split squat elicited higher BF and LG muscle activity compared to the free and Smith squats. The findings suggest that the split squat optimally stimulates the BF and LG and should consequently be incorporated into strength and conditioning programs for athletes.