The Study
Resistance Training Load Effects on Muscle Hypertrophy and Strength Gain: Systematic Review and Network Meta-analysis
This study looked at lots of different workouts and found that lifting heavy weights probably makes you stronger than lifting light weights — but lifting light weights until you’re tired can make your muscles just as big as lifting heavy ones. It’s like saying: eating lots of veggies might not make you taller, but it won’t stop you from growing — and eating meat might help you jump higher.
Analysis score
Maximum 100 for a systematic review with meta-analysis.
Where the score came from
If you lift weights until you can't do another rep, it doesn't matter if you use light or heavy weights — you'll grow your muscles about the same. But if you want to get stronger, heavier weights work better. Newbies grow muscle faster than experienced lifters, and doing more workouts helps experienced people grow more. Men get stronger than women with heavy lifting.
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 548 / 100
Quality score
The highest quality evidence. Systematic reviews and meta-analyses that pool randomized controlled trials, giving the most reliable summary of experimental evidence.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — you don't need heavy weights to build muscle if you train hard, but if you want to get stronger, go heavy.
- 2Beginners see big gains fast; experienced lifters need more volume.
- 3Men may benefit more from heavy lifting than women.
- 4Muscle growth: same for light (>15 reps), medium (9–15 reps), and heavy (≤8 reps) weights.
- 5Strength: heavy > medium > light.
- 6Untrained: +33% more muscle growth.
- 7More sessions = more growth for trained people.
- 8Men: bigger strength gains than women with heavy weights.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Medicine and Science in Sports and Exercise
Year
2020
Authors
P. Lopez, R. Radaelli, D. Taaffe, R. Newton, D. Galvão, G. Trajano, J. Teodoro, W. Kraemer, K. Häkkinen, R. Pinto
Related Content
Videos (3)
Claims (10)
When people lift weights until they can no longer complete another repetition, the amount of muscle growth is similar whether they use light, moderate, or heavy weights.
When resistance training is performed until muscle fatigue is reached, lifting light weights and lifting heavy weights result in the same amount of muscle growth.
When you lift weights until you can't anymore, you build about the same muscle size no matter how many reps you do, but doing more reps makes you stronger than doing fewer reps.
If you lift weights until you can’t do another rep, your muscles will grow about the same no matter how heavy the weights are—but you’ll get stronger faster if you lift heavier weights.
If you push your muscles as hard as you can until you can't do any more reps, that's what really makes them grow bigger. It doesn't matter how many reps you do, as long as you're giving your absolute best effort.
Lifting weights until you can't lift anymore makes muscles grow bigger no matter how heavy the weights are, but using heavier weights builds more strength than lighter ones.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.