When men and women do strength training, their fast-twitch muscle fibers grow about the same amount—so sex doesn’t really make a difference in how much these muscles get bigger.

A meta-analysis pooling individual participant data from RCTs comparing type II muscle fiber hypertrophy (via muscle biopsy) in males and females after standardized resistance training protocols (e.g., 8–12 weeks, 3–5 sets of 6–12 reps at 70–85% 1RM), with lnRR calculated for each study and heterogeneity assessed by sex subgroup.

A double-blind, parallel-group RCT assigning healthy adult males and females (n=50 per group) to identical resistance training programs (e.g., 12 weeks, 3x/week, 75% 1RM, 8–12 reps) with pre- and post-intervention muscle biopsies from vastus lateralis to measure type II fiber hypertrophy using lnRR and pd.

A prospective cohort study following 100 healthy adults (50 male, 50 female) undergoing 16 weeks of supervised resistance training, with muscle biopsies taken at baseline, 8 weeks, and 16 weeks to track type II fiber hypertrophy trends and compare sex-specific lnRR trajectories.

Analysis of pre-existing datasets from resistance training studies that include muscle biopsy data, comparing mean % change in type II fiber size between males and females after training, using lnRR and pd as reported metrics.