The Study
Molecular signatures underlying heterogenous hypertrophy responsiveness to resistance training in older men and women: a within-subject design.
This study found that when older people lift weights with more sets, some of them grow bigger muscles — but not everyone. It’s like trying two different ways to grow a plant and seeing which one works better for each plant. But we don’t know if the researchers made sure no one knew which plant got which treatment, so we can’t be 100% sure the extra sets caused the growth.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
When older people lift weights, some grow big muscles, some grow a little, and some don’t grow at all. This study found that doing more sets helps those who usually respond well, but not those who don’t respond at all. Their muscles also change in different ways at the molecular level.
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 541 / 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’re someone who doesn’t grow muscle easily, doing more sets won’t help.
- 2But if you respond well, more sets make a difference.
- 34 sets helped medium and high responders grow more muscle than 1 set.
- 4Low responders didn’t grow more muscle no matter how many sets they did.
- 5Frizzled-1 protein went up in everyone who did 4 sets.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of applied physiology
Year
2025
Authors
M. Lixandrão, M. Bamman, K. Lavin, Igor Longobardi, Guilherme Telles, Felipe C. Vechin, Felipe Damas, D. Drummer, J. McAdam, Luiz A Riani Costa, C. Libardi, Bruno Gualano, Hamilton Roschel
Related Content
Claims (9)
When people gain muscle from resistance training, the amount of growth varies between muscles, and these differences are partly linked to how similar the responses are across muscles, but much of the variation comes from personal biological traits unrelated to the workout itself.
When people lift weights regularly, their muscles usually get about 5% bigger on average, no matter what kind of weight routine they follow.
In people who already train regularly, 8 weeks of weight training causes a small increase in muscle size that is often too small to measure reliably, making it hard to tell which training methods are better.
Some older people don’t build muscle no matter how much they train—and their muscles don’t show any detectable biological changes, even when they do more exercise.
For older people, doing four sets of weight exercises instead of just one can help build more muscle—but only if their body is already somewhat responsive to exercise; if it’s not responsive at all, more sets don’t help.
Doing more weight training raises levels of a protein called Frizzled-1 in older people’s muscles, no matter whether they gain muscle or not.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.