Even though leg extensions only move one joint, they might work your front thigh muscles better than squats or leg presses because they really target one specific muscle in the quad.
Evidence from Studies
Supporting (1)
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Comparison of Muscle Hypertrophy and Strength Adaptations Induced by Back Squat and Leg Extension Resistance Exercises
The study shows that leg extensions build the front thigh muscle (rectus femoris) more than squats do, which supports the idea that this exercise works that specific muscle better.
Contradicting (2)
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Hypertrophic Effects of Single- versus Multi-Joint Exercise: A Direct Comparison Between Knee Extension and Leg Press.
The study found that leg extensions work the front thigh muscle (rectus femoris) better than leg presses, but both exercises work the rest of the quads about the same.
Quadriceps EMG/force relationship in knee extension and leg press.
The study found that leg extensions don’t activate the quadriceps or the rectus femoris more than leg presses do — both exercises use the muscles similarly.
Gold Standard Evidence Needed
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