Effects of variations in resistance training frequency on measures of muscle hypertrophy: A systematic review and meta-analysis

Abstract

This systematic review and meta-analysis examined the effects of variations in resistance training frequency on measures of muscle hypertrophy. Sixteen studies involving both trained and untrained men and women were analyzed, comparing low-frequency (1-2 sessions per muscle group per week) and high-frequency (3-6 sessions per muscle group per week) protocols, mostly with equated total weekly training volume. Results indicated no statistically significant differences in muscle hypertrophy outcomes between low- and high-frequency training when volume was matched. Effect sizes were generally small or negligible, supporting training volume as the primary driver of hypertrophic adaptations rather than frequency alone. Some individual studies suggested modest benefits of higher frequency or split routines, but these findings were inconsistent. Strength gains mirrored hypertrophy results, showing similar improvements across frequencies. Individual variability in response to frequency manipulation was noted, highlighting the potential for personalized programming. Frequency may offer practical advantages in distributing training volume and managing recovery without compromising hypertrophic outcomes. Future research should investigate long-term adaptations and individualized frequency strategies to optimize resistance training programs.