How often you lift each week doesn’t seem to matter much for building muscle — as long as you do the same total number of sets, spreading them out or grouping them doesn’t make a big difference.
Scientific Claim
Weekly resistance training frequency is not consistently associated with muscle hypertrophy in young, mostly male adults, as the posterior probability of a positive effect was less than 100%, suggesting frequency may have negligible or inconsistent effects when volume is held constant.
Original Statement
“The posterior probability of the marginal slope exceeding zero for frequency’s effect on hypertrophy was less than 100%, indicating compatibility with negligible effects.”
Evidence Quality Assessment
Claim Status
overstated
Study Design Support
Design supports claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The original text implies a definitive conclusion ('negligible effects'), but the study only shows compatibility with negligible effects — a probabilistic finding. Causal or definitive language is inappropriate.
Evidence from Studies
Supporting (1)
The Resistance Training Dose Response: Meta-Regressions Exploring the Effects of Weekly Volume and Frequency on Muscle Hypertrophy and Strength Gains
When people lift weights, doing more total sets helps muscles grow, but doing more workouts per week doesn’t necessarily make them grow bigger — unless they’re doing more total work. This study found that frequency alone doesn’t reliably boost muscle growth.