The Study
High Resistance-Training Frequency Enhances Muscle Thickness in Resistance-Trained Men.
This study tried to see if lifting weights more often makes muscles bigger, and it randomly picked who did what — so we can guess that the higher frequency might have caused the bigger muscles. But we don’t know if the people measuring the muscles knew who did what, so we can’t be totally sure.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Two groups trained with the same total amount of work, but one trained each muscle group every day, the other only once a week. After 8 weeks, both got equally strong, but the daily group got bigger muscles in the arms and thighs.
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.
- 1Yes — training more often can make specific muscles grow bigger without making you stronger, if total workout volume is the same.
- 2Muscle thickness increased more in forearm flexors and vastus lateralis for the 5-day/week group; no difference in bench press, squat, or row 1RM.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Strength and Conditioning Research
Year
2019
Authors
R. Zaroni, F. Brigatto, B. Schoenfeld, T. V. Braz, Júlio C. Benvenutti, M. D. Germano, P. H. Marchetti, M. Aoki, C. Lopes
Related Content
Claims (3)
Lifting weights more often each week helps you build bigger muscles and get stronger, but after a certain point, you don’t gain much extra strength—though your muscles can still grow. If you keep the same total amount of lifting, doing it in more frequent, lighter sessions helps strength more than muscle size.
If you're a guy who already lifts weights, doing full-body workouts five days a week will make your forearm and thigh muscles grow bigger than if you only work each muscle group once a week, after eight weeks of training.
If you're already strong and lift weights, training each muscle group either once or five times a week for eight weeks will give you about the same strength gains on the bench press, squat, and row.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.