The Study
Higher- and lower-load resistance exercise training induce load-specific local muscle endurance changes in young women: a randomised trial.
This study tried two different ways of lifting weights and saw which one made arms and legs stronger or able to do more reps. Because they randomly picked which arm/leg did which, we can guess that the weights caused the changes — but we’re not super sure because we didn’t see how they did the study in full.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Two groups of women trained their arms and legs with heavy and light weights, each side doing a different weight. After 10 weeks, their muscles got stronger and could do more reps—but which weight helped more depended on which kind of rep they tested.
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 552 / 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—choosing the right weight matters for specific endurance goals, especially in legs.
- 2But for arms, any weight works similarly.
- 3Muscle size only increased in arms with light weights.
- 4Heavy weights: better at heavy reps in legs (9.3 vs 7.5 reps).
- 5Light weights: better at light reps in legs (24.7 vs 15.2 reps).
- 6Arms: same gains no matter the weight.
- 7Only light weights made arms bigger.
- 8Legs didn't get bigger with either weight.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme
Year
2022
Authors
Matthew D Fliss, J. Stevenson, Sobhan Mardan-Dezfouli, Donna C W Li, C. Mitchell
Related Content
Claims (6)
While the majority of individuals exhibit similar hypertrophic responsiveness across high- and low-load resistance training, a subset may demonstrate load-specific responsiveness, though such responses are inconsistent and not reliably predictable.
When lifting weights with your arms, whether you use heavy or light weights, you get about the same improvement in how many reps you can do with both heavy and light weights.
Using light weights for arm exercises can make your arms slightly more muscular, but using light or heavy weights for leg exercises doesn’t change leg muscle size in young women who haven’t trained before.
Lifting heavy weights makes your legs much stronger than lifting light weights, but for your arms, both heavy and light weights make you about equally stronger.
If you lift heavy weights, you get better at doing more reps with heavy weights; if you lift light weights, you get better at doing more reps with light weights — your muscles adapt specifically to the weight you use.
Working out with weights three times a week for 10 weeks makes you better at doing more reps — but how much better depends on whether you used heavy or light weights.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.