Resistance training induces similar adaptations of upper and lower-body muscles between sexes

Abstract

The purpose of the study was to compare sex adaptations in hypertrophy, strength and contractile properties of upper and lower-body muscles induced by resistance training (RT). Eighteen RT untrained male (MG) and female (FG) students (aged 24.1 ± 1.7 years, height: 1.75 ± 0.08 m, weight: 70.4 ± 12.3 kg) undervent 7 weeks of biceps curl and squat training (2 days/week, 60–70% repetition maximum, 3–4 sets, 120 s rest intervals, reps until muscular failure). At baseline and final measurement, thickness and cross-section area, one-repetition maximum and tensiomyography parameters (contraction time − Tc and radial displacement − Dm) of elbow flexors (biceps brachii) and knee extensors (4 quadriceps muscles) were evaluated. Although MG tends to display greater absolute strength gains for upper- (p = 0.055) and lower-body (p = 0.098), for relative changes ANCOVA revealed no sex-specific differences for either of the tested variables. Significant hypertrophy was observed for all tested muscles, except for vastus intermedius in FG (p = 0.076). The Dm significantly decreased for biceps brachii (MG by 12%, p < 0.01 and FG by 13.1%, p < 0.01) and rectus femoris (MG by19.2%, p < 0.01 and FG by 12.3%, p < 0.05), while Tc values remain unchanged. These results indicate that initial morphological, functional and contractile alterations following RT are similar for males and females, and that there are no specific sex adaptations either for the upper- or lower-body muscles. The study was registered with ClinicalTrials.gov (NCT04845295).

Does Back Squat Exercise Lead to Regional Hypertrophy among Quadriceps Femoris Muscles?

“…The Shapiro–Wilk test was used to assess the normality of the distribution, whereas the homogeneity of the variances and the homogeneity of the regression slopes were tested by Levene’s test and by an interaction between the covariate and the independent variable, respectively. The reliability of the strength and ultrasound measurements was reported previously [ 20 ]. Baseline differences in CSA between measured muscles were tested by a one-way ANOVA.…”

“…The CSA of four quadriceps muscles (VM, VL, VI, and RF) was assessed using an ultrasound machine (Siemens Antares, Erlangen, Germany) with a variable high-frequency transducer (from 7 MHz to 13 MHz) and an image-fitting technique previously validated by our group [ 10 , 20 ]. Briefly, the RF CSA was measured at the level of three-fifths of the distance between the spina iliaca anterior superior and superior patellar border, whereas the CSA of VI was measured at the halfway point between the spina iliaca anterior superior and the proximal border of the patella.…”

“…The mentioned position was the same for all subjects in all training sessions. The range of motion of the exercise included a full concentric movement (up to the vertical position); during the eccentric phase, the movement was performed until the femurs were parallel to the floor, when the trochanter major and the lateral epicondyle of the femur were at the same level [ 10 , 20 ]. The height of the parallel squat was measured for each participant individually.…”

The Biological Basis of Sex Differences in Athletic Performance: Consensus Statement for the American College of Sports Medicine

“…Males and females exhibit similar relative (percentage) magnitudes of muscle hypertrophy, muscle strength, and power improvements in response to high-load resistance training (~6-12 wk) in young adults (e.g., (419,(433)(434)(435)(436)) and adults older than 50 yr (437), with the expected moderating effects of frequency, volume, and intensity (419,436). Males and females also adapted similarly (relatively) to 12-wk high-intensity interval training on the bike with similar muscle hypertrophy (5%) and increased fatigue resistance (4.8%) (438).…”

The Biological Basis of Sex Differences in Athletic Performance: Consensus Statement for the American College of Sports Medicine

“…Males and females exhibit similar relative (percentage) magnitudes of muscle hypertrophy, muscle strength, and power improvements in response to high-load resistance training (~6-12wk) in young adults (e.g., (419,(433)(434)(435)(436)) and adults older than 50yr (437), with the expected moderating effects of frequency, volume, and intensity (419,436). Males and females also adapted similarly (relatively) to 12-wk high-intensity interval training on the bike with similar muscle hypertrophy (5%) and increased fatigue resistance (4.8%) (438).…”