Mehls, K, Grubbs, B, Jin, Y, and Coons, J. Electromyography comparison of sex differences during the back squat. J Strength Cond Res 36(2): 310-313, 2022-Currently, there is limited information regarding the muscle activity differences between men and women during the traditional back squat. The back squat is a widely used exercise which stimulates lower-body musculature; thus, information regarding the muscle activity patterns during this exercise is pertinent when prescribing resistance training. This study evaluated muscle activity differences (using surface electromyography) in men and women during the traditional back squat with a load prescribed to elicit strength gains. Resistance-trained men (n 5 14) and women (n 5 14) performed 3 sets of 4 repetitions in the traditional back squat using 85% of their pretest 1 repetition maximum. Muscle activity data were collected for 6 muscles including the vastus lateralis, vastus medialis, rectus femoris, gluteus maximus, semitendinosus, and biceps femoris (BF). Independent sample t tests revealed a significantly higher normalized muscle activity in men in the BF muscle during the descending phase of the back squat. No other muscle activity differences were present between men and women. These results indicate that men activate the BF muscle during the traditional back squat to a greater extent than women. For women, it may be necessary to consider other exercises to optimally stimulate and strengthen the BF muscle during resistance training.
The aim of this study was to compare gluteus maximus-to-hamstring (GM:H) co-activation, hamstrings-to-quadriceps (H:Q) co-activation, and mean muscle activity in the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RM), gluteus maximus (GM), semitendinosus (ST), and bicep femoris (BF) muscles across a range of training loads (40%, 50%, 50%, 70%, 80% 90% 1RM) of the barbell back squat in resistance trained females. Surface electromyography (EMG) was observed in 18 healthy resistance trained females for the VL, VM, RM, GM, ST, and BF during the ascending and descending phase of the back squat. During the ascending phase, the VL, VM, RM, GM, ST, and BF displayed significantly more EMG activation at 90% 1RM compared to 40%-70% (p < .03). During the descending phase, there were no significant differences displayed in mean muscle activity at 40%-80% of 1RM compared to 90% of 1RM. There were no significant differences in H-Q co-activation and GM-H co-activation during the ascending or descending phase across external loads. These findings are similar to the results found in similar studies using male participants and support that higher training intensities (80%-90% 1RM) of the barbell back squat significantly activate muscles surrounding the hip compared to lower loads (40%-70%). The results of this study also suggest that training intensities of 80% 1RM and 90% 1RM elicits the similar musculature activation in the muscle surrounding the hip in resistance trained females. Highlights. During the back squat, mean muscle activity of the hip and leg muscles increased linearly with exercise intensity (40%-90% of one-repetition max) in resistance trained females. . No significant difference in mean activity were noted between 80% and 90% of one-repetition max during the ascending and descending phases. . During the ascending phase, 80% of one-repetition max generated the highest gluteus maximus to hamstring activity co-activation ratio. . During the descending phase, 40% of one-repetition max produced a gluteus maximus to hamstring activity co-activation ratio closest to 1.0.
Weightlifting derivatives have become an increasingly popular form of resistance training among youth athletes over the past decade. This study aimed to examine the loading profiles of youth athletes during the hang power clean to determine optimal loading parameters for force, power, rate of force development, and barbell velocity. Sixteen male youth athletes (Age: 16.94 ± 0.97 years; Height: 180.08 ± 8.14 cm; Body mass: 81.06 ± 15.04 kg; Hang Clean 1RM 70.17 ± 14.41 kg) performed three repetitions of the hang power clean at 10% intervals ranging from 30-90% of their one-repetition maximum (1RM). One-way repeated measures ANONAs revealed that external load had a significant effect on the peak and average of all variables examined (p < 0.05). Most notably, peak power was maximized at 70% 1RM which was not significantly different 60-90% 1RM. Peak rate of force development was maximized at 90% 1RM, though it was not significantly greater than 50-90%1RM. Conversely peak barbell velocity was maximized at 30% 1RM which was significantly greater than 50-90% 1RM. While the results for power are similar to that of older, stronger athletes, the youth population in this study maximized barbell velocity and rate of force development at different external loads compared to more developed athletes. These results seem to suggest that youth athletes need to achieve a higher level of strength before they are capable of training with high relative external loads while maintaining high barbell velocities.
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