Sex Differences in Resistance Training: A Systematic Review and Meta-Analysis

Area of Science:

• Exercise Physiology
• Sports Science
• Human Kinetics

Background:

• Understanding sex-based differences in response to resistance training is crucial for optimizing exercise prescriptions.
• Previous research has yielded mixed results regarding sex differences in strength and hypertrophy adaptations.

Purpose of the Study:

• To systematically review and meta-analyze existing literature to determine if males and females exhibit different responses to identical resistance training protocols for strength and hypertrophy.
• To identify potential sex-specific adaptations in response to resistance exercise.

Main Methods:

• A systematic review and meta-analysis were conducted on studies comparing male and female responses to resistance training.
• Data were analyzed using robust variance random effects modeling, with adjustments for small sample sizes.
• Statistical significance was set at P < 0.05.

Main Results:

• No significant sex difference was found for hypertrophy adaptations (effect size [ES] = 0.07 ± 0.06; P = 0.31).
• No significant sex difference was observed for lower-body strength adaptations (ES = -0.21 ± 0.16; P = 0.20).
• Females demonstrated a significantly greater effect size for relative upper-body strength gains compared to males (ES = -0.60 ± 0.16; P = 0.002).

Conclusions:

• Males and females adapt similarly to resistance training regarding hypertrophy and lower-body strength.
• Females may possess a greater capacity for relative upper-body strength increases compared to males.
• Further research is needed to elucidate the mechanisms behind the observed upper-body strength difference, including neural, muscular, or motor learning factors.