The Study
Effects of equal-volume resistance training with different training frequencies in muscle size and strength in trained men
This study compared two ways of lifting weights and saw what happened to a few guys' muscles. It didn't prove that one way is better—it just showed a tiny change in one muscle group for one group. So we can say 'maybe' or 'it's linked,' but not 'this causes that.'
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Two groups of experienced lifters trained the same total amount but one group trained once a week and the other twice a week — both for 10 weeks.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 546 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1The 3.1% bicep thickening is small and likely not noticeable visually; no strength gain means lifting heavier weights didn’t improve.
- 2Only the once-a-week group got 3.1% thicker biceps; neither group got stronger.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
PeerJ
Year
2018
Authors
P. Gentil, J. Fisher, J. Steele, M. Campos, M. H. Silva, A. Paoli, Jürgen Giessing, M. Bottaro
Related Content
Claims (6)
Among trained young men doing the same total amount of weight training, switching from working out twice a week to once a week was linked to a small increase in bicep muscle thickness, but no change in strength. This suggests that changing the schedule, not the total workload, might have triggered minor muscle growth by introducing a new stimulus.
For men who are already trained, doing resistance training once or twice a week with the same total workload does not lead to measurable increases in elbow strength, suggesting that further strength gains may not occur even with different training frequencies.
In trained young men, performing resistance training once or twice a week for 10 weeks with a fixed volume leads to little increase in muscle size and no improvement in strength, indicating that further progress may require a change in training approach.
For men who already train regularly, doing resistance workouts once or twice a week with the same total workload as more frequent sessions results in similar gains in muscle size and strength.
Changing from training twice a week to once a week might trigger small muscle growth in experienced lifters, even if the total amount of work stays the same, suggesting that changing how the training is structured, rather than how often it occurs, could help overcome plateaus.
When the total amount of weight training is the same each week, doing it in two sessions produces more muscle growth than doing it in one session.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.