The leg curl is the primary machine hamstring isolation exercise. Unlike the RDL or good morning (hip hinge patterns), the leg curl trains the hamstring as a knee flexor — targeting a different function and the biceps femoris more directly.
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Form Guide
Step-by-step: Leg Curl
1Lying leg curl: lie face down, pad just below your calf. Hips stay flat on the pad throughout.
2Curl the pad toward your glutes as far as possible — aim for full knee flexion.
3Do not let your hips rise off the pad (if they do, the weight is too heavy).
4Lower with control — 2–3 second eccentric.
Common Mistakes
What most people get wrong
Hips rising: reduces hamstring stretch and shifts load to the lower back.
Partial range of motion: get the pad all the way to the glutes.
Programming
How to program the Leg Curl
3–4 sets of 10–15 reps. Include both leg curls (knee flexion emphasis) and RDLs (hip extension emphasis) for complete hamstring development — they train the muscle in different functions.