Squats vs. Leg Extensions: Which Builds Thigh Muscles Better?
Comparison of Muscle Hypertrophy and Strength Adaptations Induced by Back Squat and Leg Extension Resistance Exercises
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Leg extensions produced significantly greater hypertrophy in the rectus femoris at all three measurement sites compared to back squats.
Common fitness wisdom says compound lifts like squats stimulate more total muscle growth—but here, an isolation move outperformed it in a major thigh muscle.
Practical Takeaways
If you want to maximize rectus femoris growth, include leg extensions in your routine—even if you squat regularly.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Leg extensions produced significantly greater hypertrophy in the rectus femoris at all three measurement sites compared to back squats.
Common fitness wisdom says compound lifts like squats stimulate more total muscle growth—but here, an isolation move outperformed it in a major thigh muscle.
Practical Takeaways
If you want to maximize rectus femoris growth, include leg extensions in your routine—even if you squat regularly.
Publication
Journal
Journal of Strength & Conditioning Research
Year
2025
Authors
Witalo Kassiano, Bruna Costa, Gabriel Kunevaliki, Felipe Lisboa, Aline Prado, Luis Alves, Ian Tricoli, Natã Stavinski, Jarlisson Francsuel, Edilson S. Cyrino
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Claims (10)
Compound exercises involving greater total muscle mass do not produce superior hypertrophy in target muscles compared to isolation exercises when training volume and effort are equated.
Squats make the lower part of the outer thigh muscle grow more than leg extensions do, probably because squats involve more hip and knee movement together.
Which leg exercise you choose matters: leg extensions grow the front thigh muscle more, squats grow the lower outer thigh more and make you stronger at squats—but both help you get stronger at leg extensions.
Even if you only do squats, you still get almost as strong at leg extensions as someone who only does leg extensions—so squats aren’t useless for that movement.
Doing leg extensions makes the front thigh muscle grow more evenly along its length than doing squats, which don’t stimulate that muscle as much.