The Resistance Training Dose-response: Effects Of Weekly Volume On Strength Gain

PURPOSE: This meta-analysis explored the nature of the continuous dose-response relationship between weekly resistance training (RT) set volume and strength gain. METHODS: Each RT intervention included healthy participants <70 years old, utilized a dynamic RT intervention ≥4 weeks differing in set volume and/or frequency while controlling for other RT variables, and measured maximal strength using a dynamic (up to a 10RM), isometric, or isokinetic assessment. All contributing RT sets were classified as direct or indirect: direct sets were those that trained the exact exercise used for the strength assessment while indirect sets were any that were likely to meaningfully train the muscle(s) involved in the strength assessment. Then, weekly volume for indirect sets was quantified as 1 for ‘total,’ 0.5 for ‘fractional,’ and 0 for ‘direct.’ A series of multi-level meta-regressions were performed, with all models adjusted for frequency, intervention duration, and training status. RESULTS: The multi-level meta-regression models for the effect of weekly set volume on strength gain included 66 studies, 490 effects, and 2,020 participants. The relative evidence was strongest for the ‘fractional’ quantification method (2 x Log(BF) = 18.21 to 45.96). Model comparisons revealed the reciprocal model was the best fit, with a marginal slope of 0.21% [95% CrI: 0.16%, 0.26%]. CONCLUSIONS: The best fit meta-regression model indicated a positive dose-response relationship whereby higher weekly ‘fractional’ set volumes resulted in additional strength gain, though with strong diminishing returns and a functional plateau. These findings align with previous meta-analytic work, and expands on them by including new data, a novel volume quantification method, and nonlinear relationships.