Why some people grow muscles better than others when lifting weights
Molecular signatures underlying heterogenous hypertrophy responsiveness to resistance training in older men and women: a within-subject design.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
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.
Surprising Findings
Low responders showed no molecular changes regardless of training volume.
Common belief is that more training always triggers some biological adaptation—even if muscle doesn’t grow. This study shows that for some, the muscle cells literally don’t 'hear' the signal.
Practical Takeaways
If you’re an older adult not gaining muscle despite consistent training, try increasing volume—but know it may not work if you’re a low responder.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
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.
Surprising Findings
Low responders showed no molecular changes regardless of training volume.
Common belief is that more training always triggers some biological adaptation—even if muscle doesn’t grow. This study shows that for some, the muscle cells literally don’t 'hear' the signal.
Practical Takeaways
If you’re an older adult not gaining muscle despite consistent training, try increasing volume—but know it may not work if you’re a low responder.
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
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Claims (6)
Individual hypertrophic responsiveness to resistance training exhibits moderate inter-muscle correlation, but a substantial proportion of variability is attributable to non-exercise-specific biological factors.
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.
People who build the most muscle from weight training show increased activity in their muscle cells’ systems that rebuild proteins, use energy during exercise, and fix damaged proteins.
People who build some muscle with more training (but not a lot) show reduced activity in systems that break down muscle and increased activity in systems that help move proteins around and respond to hormones.
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.