The Study
Resistance exercise load does not determine training-mediated hypertrophic gains in young men.
This study tested whether lifting light weights or heavy weights makes your muscles bigger, and found that both worked about the same—like using a small shovel or a big shovel to dig a hole, and ending up with the same size hole. But it doesn’t prove one is better than the other for everyone, just for these 18 guys.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Scientists had guys lift either light weights or heavy weights until they couldn't do another rep, for 10 weeks, to see which made muscles bigger.
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 554 / 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 — if you want bigger muscles, light weights to failure work just as well as heavy ones.
- 2But if you want to lift heavier things, you need to train with heavy weights.
- 3Light weights (30% max) made muscles grow 6.8% bigger; heavy weights (80% max) made them grow 7.2% bigger — almost the same.
- 4But heavy weights made them stronger at lifting max weight.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of applied physiology
Year
2012
Authors
C. Mitchell, T. Churchward-Venne, Daniel W D West, N. Burd, L. Breen, S. Baker, Stuart M Phillips
Related Content
Claims (6)
Increases in strength are mainly due to changes in how the nervous system activates muscles, while increases in muscle size are mainly due to the total amount of training performed within a repetition range of 4 to 30 reps.
In young men, lifting lighter weights to muscle failure for 10 weeks results in about the same increase in quadriceps muscle size as lifting heavier weights to failure, suggesting that how heavy the weight is may not matter as much as reaching muscle fatigue during training.
In young men, lifting weights to failure produces similar increases in size for both slow-twitch and fast-twitch muscle fibers, whether using light or heavy weights.
In young men, the level of a specific molecular signal detected one hour after weight training does not predict how much muscle mass will be gained over time.
When people lift light weights until they can't do another rep, they gain more endurance for that specific lifting style than when they lift heavy weights, even if the total effort feels similar.
When young men lift heavy weights (80% of their maximum), they gain more strength than when lifting light weights (30% of their maximum), even if both groups end up with the same amount of muscle growth.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.