Effect of external load on muscle activation during the barbell back squat

Abstract

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.

A Wearable Hip Exoskeleton for Anaerobic Exercise in Healthy Adults

“…In addition, even in exercises with large movements or those performed in a prone position, such as kick-backs, mountain climbs, and split jacks, there was a tendency for abdominal and lower-extremity muscle activity to be higher with the Bot Fit. This con rms previous ndings that resistance training increases trunk-and leg-muscle activation through increased external loading and higher training intensity 37 . These results emphasize the effectiveness of the Bot Fit in developing and strengthening target muscles and suggest its potential as a tool to enhance tness exercises.…”

Comparison of kinematics and electromyography in the last repetition during different maximum repetition sets in the barbell back squat

“…However, it is unclear if technique remains consistent across the entire spectrum of these loads when training to, or near voluntary failure. Earlier research supports the assumption that technical variations depend on load, as evidenced by the influence of load on EMG signals ( Mehls et al, 2021 ; Martinez, Coons & Mehls, 2023 ). Repetition range might influence joint and barbell kinematics and EMG amplitude during different phases of the lift due to compensatory strategies, which are indirect measures ( Morton et al, 2019 ; Larsen, Haugen & van den Tillaar, 2022 ) of understanding differences between a given repetition range and 1RM squat strength.…”

The Effect of Restricted Hip Extension on Muscle Activity During Functional Movements

“…A final potential reason the current study did not see a significant difference in muscle activity is low absolute loading. It has been well established that as external load on the body or a muscle increase, muscle activity also increases (19). The functional movements tested in this study did not apply any external loading above the participants bodyweight.…”

“…To the author's knowledge, only one study has observed the effects of restricted hip extension on muscle activity during functional movement patterns (a bilateral air squat) (17). Additionally, it has been noted that males and females adopt different strategies to complete movements for a variety of reasons and that females have higher rates of lower extremity injury than males (18,19). To better understand the effects of restricted hip extension on muscle activity in healthy females during functional movements, further investigation is required.…”