Hip Thrust Versus Back Squat Training in Untrained Adults

Cross-sectional area of the upper, middle, and lower gluteus maximus was measured via magnetic resonance imaging (MRI) at baseline and following the 9-week training intervention. T1-weighted transverse images were obtained using a 3T MRI scanner, and muscle borders were manually traced using ImageJ software by a single investigator blinded to group allocation. Bilateral (left + right) mCSA values were summed at each of three standardized anatomical sites (upper, middle, and lower gluteus maximus) to assess site-specific hypertrophic response to training.

Dynamic lower-body strength was assessed via 3-repetition maximum (3RM) testing for the barbell hip thrust, barbell back squat, and barbell deadlift at baseline and following the 9-week training intervention

Surface electromyography (sEMG) was used to assess muscle excitation of the right upper, middle, and lower gluteus maximus and the right gluteus medius during a single 10-repetition-maximum (10RM) set of both the barbell back squat and barbell hip thrust exercises, performed during participants' first training session. Wireless sEMG electrodes were placed at standardized anatomical sites, and signals were sampled at 1000 Hz, rectified, filtered, and smoothed before being normalized to each participant's maximum voluntary isometric contraction (MVIC) for the corresponding muscle. Mean and peak sEMG amplitudes were calculated for each muscle site during each exercise and compared between the back squat and hip thrust conditions.