This study compared the effects of two lower-body resistance training exercises - the barbell back squat and the barbell hip thrust - on muscle growth and strength in untrained young adults. Thirty-four participants were randomly assigned to train using either the back squat or the hip thrust, two times per week for nine weeks. Muscle size (via MRI) and strength (via weightlifting tests) were measured before and after training to determine whether one exercise produced greater improvements than the other, particularly in the gluteal muscles. Muscle activity during the first training session was also measured using surface electromyography (sEMG) to see whether early muscle activation could predict later muscle growth.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
39
Participants performed training twice per week (non-consecutive days) for 9 weeks, totaling 15-17 supervised sessions. Training volume progressed weekly: 3 sets in week 1, 4 sets in week 2, 5 sets in weeks 3-6, and 6 sets in weeks 7-9, matching the set-volume scheme used in the hip thrust group. Each set consisted of 8-12 repetitions performed to volitional muscular failure (defined as the inability to complete another repetition with proper form); load was adjusted as needed to keep repetitions within this range. Repetitions were performed with a controlled tempo (\~1-second concentric, \~2-second eccentric). All training sessions were supervised by study personnel. Participants were instructed to refrain from any other lower-body resistance training for the duration of the study.
School of Kinesiology
Auburn, Alabama, United States
Hypertrophy
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.
Time frame: Baseline and 9 weeks
3RM strength testing
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
Time frame: Baseline and 9 weeks
One-bout EMG gluteal maximus recordings
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.
Time frame: Single training session within the first week of the intervention.
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