Men and women gain muscle at roughly the same 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 from 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, despite males having 10- to 20-fold higher testosterone levels than females.”
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 meta-analyses of RCTs, which support the conclusion. The language 'does not significantly alter' is appropriately probabilistic and reflects the evidence.
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 EvidenceThe relative muscle hypertrophy response to resistance training in males versus females when matched for training volume and experience.
The relative muscle hypertrophy response to resistance training in males versus females when matched for training volume and experience.
What This Would Prove
The relative muscle hypertrophy response to resistance training in males versus females when matched for training volume and experience.
Ideal Study Design
A meta-analysis of 40+ RCTs comparing % change in muscle CSA or FFM in males and females following identical resistance training protocols (volume, load, frequency), controlling for age, training status, and nutrition.
Limitation: Heterogeneity in outcome measures (DXA vs. ultrasound) may reduce precision.
Randomized Controlled TrialLevel 1bIn EvidenceCausal equivalence of muscle protein synthesis response to resistance training between sexes.
Causal equivalence of muscle protein synthesis response to resistance training between sexes.
What This Would Prove
Causal equivalence of muscle protein synthesis response to resistance training between sexes.
Ideal Study Design
A double-blind RCT with 40 healthy young adults (20 male, 20 female), matched for fitness, performing identical resistance training, with muscle MPS measured via D2O tracer over 24h post-exercise.
Limitation: Short-term MPS may not reflect long-term hypertrophy.
Prospective Cohort StudyLevel 2bLong-term muscle gain trajectory in men and women over a training career.
Long-term muscle gain trajectory in men and women over a training career.
What This Would Prove
Long-term muscle gain trajectory in men and women over a training career.
Ideal Study Design
A 10-year prospective cohort of 100 men and 100 women starting resistance training at age 18–20, tracking annual FFM gain via DXA, training volume, and hormonal profiles.
Limitation: Confounding by lifestyle, diet, and societal training norms.
Evidence from Studies
Supporting (1)
Load-induced human skeletal muscle hypertrophy: Mechanisms, myths, and misconceptions.