Men and women gain muscle at about the same relative rate when they train the same way—women just start with less muscle, so they gain less in absolute numbers.
Scientific Claim
Biological sex does not significantly alter the relative percentage gain in muscle mass or strength following resistance training, despite large differences in baseline testosterone levels between males and females.
Original Statement
“Multiple meta-analyses have reported similar relative increases in muscle mass and strength following RET... no sex-based differences in muscle protein synthesis rates over 24 h following RET... postmenopausal females can gain, relatively, similar amounts of muscle to age-matched men.”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design cannot support claim
Appropriate Language Strength
probability
Can suggest probability/likelihood
Assessment Explanation
The claim is based on synthesis of multiple RCTs and meta-analyses. The language 'does not significantly alter' is statistically precise and appropriate for a narrative review.
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.
Systematic Review & Meta-AnalysisLevel 1aIn EvidenceQuantifies whether sex differences exist in relative muscle hypertrophy after resistance training across all high-quality RCTs.
Quantifies whether sex differences exist in relative muscle hypertrophy after resistance training across all high-quality RCTs.
What This Would Prove
Quantifies whether sex differences exist in relative muscle hypertrophy after resistance training across all high-quality RCTs.
Ideal Study Design
A meta-analysis of all RCTs comparing % change in muscle CSA or FFM in men vs. women after 8+ weeks of standardized resistance training, with subgroup analysis by age and training status.
Limitation: Cannot assess hormonal mediation mechanisms.
Randomized Controlled TrialLevel 1bTests whether testosterone suppression in men reduces relative hypertrophy to female levels.
Tests whether testosterone suppression in men reduces relative hypertrophy to female levels.
What This Would Prove
Tests whether testosterone suppression in men reduces relative hypertrophy to female levels.
Ideal Study Design
A double-blind RCT of 40 men, randomized to testosterone suppression (GnRH antagonist) or placebo during 12 weeks of resistance training, comparing % change in muscle CSA to a matched female group.
Limitation: Ethical constraints on hormone suppression in healthy men.
Prospective Cohort StudyLevel 2bTracks long-term hypertrophy trajectories in men and women over decades of training.
Tracks long-term hypertrophy trajectories in men and women over decades of training.
What This Would Prove
Tracks long-term hypertrophy trajectories in men and women over decades of training.
Ideal Study Design
A 20-year prospective cohort of 500 men and 500 women tracking annual muscle mass changes via DXA, training volume, and hormone levels from early adulthood to middle age.
Limitation: High attrition and confounding by life events.
Evidence from Studies
Supporting (1)
Load-induced human skeletal muscle hypertrophy: Mechanisms, myths, and misconceptions.