Why stretching muscles under load makes them grow bigger
The interplay between muscle length, range of motion, and exercise selection: a review
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Training at shorter muscle lengths with higher torque did NOT lead to greater hypertrophy.
Common belief: more force = more growth. This shows that even when muscles generate more force in a shortened position, they don’t grow more—contradicting traditional load-based models.
Practical Takeaways
Prioritize exercises that load muscles at their longest length—e.g., deep squats, Romanian deadlifts, full-range dumbbell curls, and bottom-position leg extensions.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Training at shorter muscle lengths with higher torque did NOT lead to greater hypertrophy.
Common belief: more force = more growth. This shows that even when muscles generate more force in a shortened position, they don’t grow more—contradicting traditional load-based models.
Practical Takeaways
Prioritize exercises that load muscles at their longest length—e.g., deep squats, Romanian deadlifts, full-range dumbbell curls, and bottom-position leg extensions.
Publication
Journal
Sports Medicine International Open
Year
2025
Authors
G. F. Pedrosa, Mariano Rezende Pereira, Witalo Kassiano
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Claims (5)
When comparing full range of motion to lengthened partials, observed hypertrophy differences may be confounded by differences in peak resistance location, making it difficult to isolate the effect of muscle length alone.
Lifting weights when your muscles are stretched out more (like at the bottom of a squat or a full bicep curl) tends to make them grow bigger than lifting with your muscles mostly shortened, as long as there's still resistance pushing back when they're stretched.
Just stretching your muscle under light weight won’t make it grow — you need to push hard while it’s stretched out, like doing a bicep curl slowly at the bottom where it’s fully extended.
Doing a full squat or starting a bicep curl from the bottom makes your muscles grow more at the far ends (like the top of your thigh or the outer part of your bicep) than doing partial reps from the top.
Even if you lift heavier weights with your muscles mostly bent, you don’t grow bigger muscles than if you lift lighter weights with your muscles stretched out — the stretch matters more than how heavy the weight is.