Quadriceps effort during squat exercise depends on hip extensor muscle strategy

Abstract

Hip extensor strategy, specifically relative contribution of gluteus maximus versus hamstrings, will influence quadriceps effort required during squat exercise, as hamstrings and quadriceps co-contract at the knee. This research examined the effects of hip extensor strategy on quadriceps relative muscular effort (RME) during barbell squat. Inverse dynamics-based torque-driven musculoskeletal models were developed to account for hamstrings co-contraction. Net joint moments were calculated using 3D motion analysis and force platform data. Hamstrings co-contraction was modelled under two assumptions: (1) equivalent gluteus maximus and hamstrings activation (Model 1) and (2) preferential gluteus maximus activation (Model 2). Quadriceps RME, the ratio of quadriceps moment to maximum knee extensor strength, was determined using inverse dynamics only, Model 1 and Model 2. Quadriceps RME was greater in both Models 1 and 2 than inverse dynamics only at barbell loads of 50-90% one repetition maximum. The highest quadriceps RMEs were 120 ± 36% and 87 ± 28% in Models 1 and 2, respectively, which suggests that barbell squats are only feasible using the Model 2 strategy prioritising gluteus maximus versus hamstrings activation. These results indicate that developing strength in both gluteus maximus and quadriceps is essential for lifting heavy loads in squat exercise.

A Comparison of Gluteus Maximus, Biceps Femoris, and Vastus Lateralis Electromyography Amplitude in the Parallel, Full, and Front Squat Variations in Resistance-Trained Females

“…Alternatively, the hamstrings might not be highly activated because increasing hamstrings reliance necessitates greater knee extensor moments to counter the hamstrings' knee fl xion moment. 61 However, the MVIC position for the vastus lateralis is obtained with both the hip and knee fl xed to 90°. 54 This is the knee angle at which, in the squat, there is a notable amount of net knee extension moment.…”

Weaker lower extremity muscle strength predicts traumatic knee injury in youth female but not male athletes

“…The 1RM barbell squat test is a measure of maximum muscular strength of the thigh and hip muscles (quadriceps, the gluteus muscles, hamstrings and hip adductors) 17 and the relative 1RM, 1RM value expressed relative to bodyweight (r1RM), was used. The 1RM barbell squat was performed according to Fysprofilen.…”

The Comparison of the Gluteus Maximus Activity during Various Prone Hip Extension in Subject with Chronic Low Back Pain

“…Based on the muscle attachment, GM showed increased leverage to its superior attachment to the dorsal ilium and was involved primarily in hip extension and lateral rotation [28]. A previous study finding suggested that the GM and RF perform a hip extensor muscle strategy synergistically during the ascending phase of standing squat exercise [32].…”