Single-Leg Leg Curl
How to Do a Single-Leg Leg Curl
Adjust the machine so the working knee aligns with the machine's pivot and the roller sits comfortably near the lower calf or ankle.
Lie face down or use the machine's intended body position and place only the working leg under the moving pad.
Hold the handles and keep the hips, torso, and working thigh stable against the support.
Brace lightly and bend the working knee to curl the heel toward the glute.
Continue through your comfortable range without lifting the hips or rotating the pelvis.
Pause briefly near peak knee flexion and contract the hamstring.
Lower the pad slowly until the working leg returns toward full comfortable extension.
Finish all planned reps on that leg, then switch sides and match the range, tempo, and repetitions.
Form Check & Technique
DO THIS (Technique Tips)
- Align the knee with the machine pivot.
- Keep the hips supported.
- Pause briefly at peak flexion.
- Control the eccentric.
- Train the weaker side first when needed.
- Match range and tempo between legs.
- Use a load that lets the thigh stay still.
AVOID THIS (Common Mistakes)
- Knee Not Aligned With the Pivot — Fix: adjust the seat or body position before loading the machine.
- Hips Lifting Off the Pad — Fix: lower the load and keep the pelvis supported.
- Twisting Toward the Working Side — Fix: hold the handles and keep the hips square.
- Using Momentum — Fix: curl and lower slowly instead of jerking the stack.
- Cutting the Eccentric Short — Fix: return toward full comfortable extension under control.
- Using Different Range on Each Side — Fix: standardize pad setup and range before comparing strength.
- Doing Extra Reps on the Strong Side — Fix: start with the weaker side and match the clean repetition count.
About Single-Leg Leg Curl
The single-leg leg curl is a unilateral machine hamstring exercise in which one knee flexes against resistance at a time. On a prone machine, align the knee with the machine pivot, place the roller near the lower calf or ankle, keep the hips supported, curl the heel toward the glute, pause, and lower slowly. Training one side at a time makes strength and control differences easier to identify.
Single-Leg Leg Curl Muscles Worked
The hamstrings are the primary muscles responsible for knee flexion in the single-leg curl.
- The gastrocnemius can assist because it also crosses the knee.
- The machine supports the rest of the body so the working leg can be trained without the opposite hamstring helping directly.
Sets & Reps Guidance
Technique / Learning
Technique: 2–3 sets of 10–15 light reps per leg while learning machine alignment.
Strength Focus
Heavy accessory work: 3–4 sets of 6–10 reps per leg with strict machine control.
Muscle Growth (Hypertrophy)
Muscle growth: 3–4 sets of 8–15 reps per leg with a controlled eccentric and brief top pause.
General training baseline. Need.fit automatically adjusts exact sets, reps, and working weight based on your individual fitness level, recovery, and progress over time.
Exercise Variations & Alternatives
Standing Leg Curl
Unilateral knee-flexion exercise performed standing on a machine, cable, or band.
Lying Leg Curl
Bilateral prone leg curl using the same basic knee-flexion pattern.
Seated Leg Curl
Seated machine hamstring curl with the hips flexed.
Banded Leg Curl
Elastic-resistance knee-flexion alternative for home training.
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Why Use a Single-Leg Leg Curl?
Training each leg separately prevents the stronger side from sharing the load during the same repetition. It also makes differences in range, strength, and control easier to notice and track.
Single-Leg vs Two-Leg Leg Curl
The bilateral version is efficient and usually allows a heavier total stack load. The single-leg version uses less total weight but lets you train and compare each hamstring independently.
Single-Leg Lying Curl vs Single-Leg Seated Curl
A prone machine places the hip closer to neutral, while a seated machine places the hip in flexion.
- Both train knee flexion.
- Use the machine available to you and follow its pivot and pad adjustments rather than forcing one setup onto another design.
Which Leg Should You Start With?
If one side is weaker or less coordinated, begin with that side and match the same reps on the stronger side. This keeps the stronger leg from setting a volume target the weaker side cannot reproduce cleanly.
How to Set the Roller Pad
Place the roller against the lower leg near the ankle without loading directly onto an uncomfortable joint or tendon area. The exact position varies by machine, but it should let the knee move smoothly through the machine's arc.
How Much Range of Motion Should You Use?
Use a comfortable full range that keeps the hips and thigh stable. Muscle & Strength recommends bringing the heel toward the glute and pausing at the top; do not chase range by lifting the pelvis or twisting.
How to Program Single-Leg Curls
They fit well after compound lower-body exercises or after a hip hinge. Moderate-to-high reps are useful for hypertrophy, while heavier controlled sets can provide additional unilateral strength work.
Sources & References
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