The lying down hamstring curl (also called the prone leg curl or lying leg curl) is a machine-based isolation exercise for the hamstrings performed face-down on a padded bench with the legs extended and the ankles hooked under a roller pad. It is the most commonly used machine hamstring exercise and one of the most effective ways to isolate the knee flexion function of the hamstrings with precise, progressive loading.
What the Lying Down Hamstring Curl Is
The lying hamstring curl involves:
- Lying face-down (prone) on the leg curl machine
- Legs extended with the ankle pad positioned just above the heels
- Curling both legs (bilateral) or one leg (unilateral) against the resistance by bending the knees
- The movement is from near-full knee extension to maximum comfortable knee flexion and back
This is an open chain exercise: the foot moves freely in space rather than being fixed against a surface. As covered in the open chain knee extension article on this site, open chain exercises specifically isolate the target muscle without the co-contraction of surrounding muscles that occurs during closed chain movements.
Muscles Targeted
Primary:
- Biceps femoris (long and short heads): The primary lateral hamstring muscle. The long head crosses both the hip and knee; the short head crosses only the knee.
- Semitendinosus: Medial hamstring, crosses both hip and knee.
- Semimembranosus: Medial hamstring, crosses both hip and knee.
Secondary:
- Gastrocnemius: The calf muscle crosses the knee posteriorly and contributes to knee flexion. Its contribution during the lying curl is greater than during the seated curl because the ankle position changes the gastrocnemius’s effective length.
- Popliteus: Contributes to the initiation of knee flexion through tibial internal rotation (the screw-home mechanism, as covered in the tibial internal rotation article on this site).
Lying Down vs Seated Hamstring Curl: The Key Difference
The lying (prone) and seated hamstring curl machines both target the hamstrings through knee flexion, but the hip position fundamentally changes the training stimulus.
Hip position in the lying curl: The hip is in extension (flat on the bench). With the hip extended, the hamstrings (which cross both the hip and knee) are in a relatively shortened position at the hip end. This means the hamstrings begin the curl at a shorter overall length.
Hip position in the seated curl: The hip is flexed to approximately 90 degrees (sitting position). With the hip flexed, the hamstrings are stretched at the hip end. Starting the knee flexion from this stretched hip position places the hamstrings under greater initial tension and through a longer effective range.
The practical implication:
The seated hamstring curl generally produces greater peak hamstring tension and a greater stretch-shortening cycle stimulus because of the hip-flexed starting position. The lying hamstring curl is somewhat easier on the hamstrings overall but is more comfortable for most people and is the version available in most commercial gyms.
Both versions have a place in a complete hamstring training programme.
Step-by-Step Technique: Machine Version
Setup
- Adjust the machine to fit your body:
- Lie face-down on the bench with the knee joint aligned at the edge of the pad (the knee should be at the pivot point of the machine’s arm)
- Position the ankle roller pad just above the heels (not directly on the Achilles tendon)
- The thighs should be fully supported by the bench pad
- Some machines have an angled bench that places the hips in slight flexion; this is fine and increases the hamstring stretch slightly
- Grip the handles on the sides of the machine for stability
- Select the appropriate resistance
The Curl
- Take a breath and brace the core gently
- Curl both legs upward by bending the knees
- Continue until the knees are at maximum comfortable flexion (ideally 90 degrees or beyond)
- At the top position, squeeze the hamstrings firmly for 1 to 2 seconds
- Lower slowly under control, taking 2 to 3 seconds
- Return to the near-extended starting position without fully locking out the knees
- Repeat for the prescribed reps
Key Technique Cues
Keep the hips down: The most critical cue. As the knees curl upward toward maximum flexion, the natural tendency is for the hips to rise off the bench, bringing the pelvis into posterior tilt. Hip lifting reduces the hamstring isolation and shifts load toward the lower back. Press the hips firmly into the bench pad throughout the entire set.
Controlled eccentric: The lowering phase should take 2 to 3 seconds. The eccentric phase of the hamstring curl is particularly important for hamstring injury prevention: the hamstrings must control high forces during eccentric lengthening (as in the late swing phase of running), and the eccentric phase of the curl develops this quality.
Full range of motion: Aim to reach at least 90 degrees of knee flexion at the top of each curl. Stopping well short of 90 degrees significantly reduces the training stimulus by avoiding the peak contraction range.
Foot position: The feet can be neutral (toes pointing straight back), internally rotated slightly (toes toward each other), or externally rotated slightly (toes apart). Internal foot rotation may increase medial hamstring (semitendinosus and semimembranosus) activation. External rotation may increase lateral hamstring (biceps femoris) activation. Neutral position provides a balanced stimulus.
No momentum: The curl should be driven entirely by hamstring contraction, not by swinging the legs or using the hips. Momentum reduces the effective load on the hamstrings and is particularly problematic during the eccentric lowering phase.
Dumbbell Lying Hamstring Curl (Home Alternative)
For people without access to a leg curl machine, the dumbbell hamstring curl replicates the lying curl movement using a dumbbell held between the feet.
How to Do It
- Lie face-down on a flat bench or on the floor
- Hold a dumbbell between the feet (one end resting on the soles of both feet, or pinched between the inner arches)
- The legs are extended in the starting position
- Curl both legs upward by bending the knees, raising the dumbbell
- Hold for 1 to 2 seconds at the top
- Lower slowly under control
- Complete the prescribed reps
Dumbbell weight selection: Begin lighter than expected. Holding a dumbbell between the feet is less stable than the machine’s ankle pad, and the instability makes the exercise more challenging at a given load than the machine version.
Stability tips:
- Pressing the feet firmly together creates a more stable dumbbell grip
- Using a dumbbell with a hexagonal shape (rather than round) reduces rolling
- The inner arch grip (dumbbell between the arches of both feet) is typically more stable than the sole-top grip for heavier dumbbells
Sets and reps: 3 sets of 10 to 12 (the dumbbell version typically uses slightly higher reps than the machine due to the lighter loads achievable)
Single-Leg Lying Hamstring Curl
The unilateral version develops each hamstring independently and addresses side-to-side asymmetries.
How to Do It
- Set up as for the bilateral version
- Place one leg aside (resting on the bench but not curling)
- Curl the working leg only
- The resistance used is significantly less than the bilateral version (approximately 55 to 65 percent of the bilateral load per leg)
- Complete all reps on one side before switching
Why unilateral is important: As covered in the prevent hamstring injuries article on this site, hamstring asymmetry is a significant injury risk factor. The single-leg version directly measures and addresses side-to-side differences that the bilateral version conceals.
Sets and reps: 3 sets of 10 to 12 per side
Common Errors and Fixes
Error 1: Hips Rising Off the Bench
What it looks like: The pelvis lifts upward as the knees curl, with the lower back arching significantly.
Why it happens: The hamstrings are not strong enough to complete the full range curl without the hip flexors and lower back assisting, or the resistance is too heavy.
Fix: Reduce the resistance and consciously press the hips into the bench throughout the set. If hips continue to rise, reduce the range of motion to the point where the hips can remain flat, and build from there.
Error 2: Shortened Range of Motion
What it looks like: The knees only reach 45 to 60 degrees of flexion rather than 90 degrees or beyond.
Why it happens: The resistance is too heavy for the full range, or the machine is set up incorrectly (ankle pad positioned too low, so the knee is not at the pivot point).
Fix: Check the machine setup first. If setup is correct, reduce the resistance to allow the full range to be completed.
Error 3: Rapid Eccentric Phase
What it looks like: The legs drop rapidly to the starting position rather than being lowered under control.
Why it happens: Fatigue or habit of using momentum.
Fix: Count 2 to 3 seconds during every lowering phase. The eccentric phase is critical for hamstring injury prevention and should never be rushed.
Error 4: Ankle Pad Positioned on the Achilles Tendon
What it looks like: The ankle pad sits directly on the Achilles tendon rather than just above it on the lower calf.
Why it matters: Direct pressure on the Achilles tendon is uncomfortable and can potentially irritate the tendon with repeated loading.
Fix: Position the ankle pad just above the heel, on the lower calf rather than on the tendon itself.
Error 5: Gripping the Handles Too Tensely
What it looks like: The athlete grips the handles with white-knuckle tension throughout the set.
Why it matters: Excessive upper body tension can produce neck and shoulder strain and also interferes with the focus on the hamstring contraction.
Fix: Hold the handles lightly for stability only, rather than gripping tightly. The hands are there for balance, not for force production.
Progressions
Beginner: Bilateral lying curl, machine, 3 x 12 at a moderate load. Focus on full range and controlled eccentric.
Intermediate: Single-leg lying curl, 3 x 10 per side. Or bilateral curl with slow eccentric (5 seconds down), 3 x 8.
Advanced: Single-leg curl with slow eccentric (4 to 5 seconds down), 3 x 8 per side. Or weighted dumbbell curl with pause at the top, 3 x 10.
Nordic curl integration: Once the single-leg curl with slow eccentric is well-established, the Nordic hamstring curl (as covered in the how to do nordic curls at home article on this site) provides the eccentric hamstring loading at longer muscle lengths that the lying curl does not adequately address.
Programming the Lying Down Hamstring Curl
As an isolation accessory exercise:
Most commonly placed after primary posterior chain compound exercises (Romanian deadlift, hip thrust, good morning).
3 to 4 sets of 10 to 12 at moderate load, 2 times per week.
For hamstring hypertrophy:
The lying hamstring curl is one of the most effective exercises for hamstring hypertrophy due to its isolated loading and the ability to train to failure safely. Combined with a hip-extension hamstring exercise (RDL, single-leg RDL) for complete posterior chain development:
- Romanian deadlift: 4 x 8 (hip extension emphasis)
- Lying hamstring curl: 3 x 12 (knee flexion emphasis)
For injury prevention:
The lying hamstring curl develops the basic knee flexion strength of the hamstrings. For comprehensive hamstring injury prevention, complement with:
- Nordic hamstring curl (eccentric at long length)
- Single-leg RDL (hip extension under load)
- Hamstring bridge series (as covered in the hamstring bridge article on this site)
Progressive loading:
Increase the weight by the smallest increment available when 3 sets of 12 can be completed with full range and a controlled 3-second eccentric. Consistency of progression over months rather than large jumps is the most reliable approach.
Frequently Asked Questions
Is the lying hamstring curl better than the seated?
Neither is universally better but they have specific advantages. The seated curl produces greater hamstring tension through the stretched hip-flexed position and is gaining favour in hypertrophy-focused training. The lying curl is more commonly available, comfortable for most people, and is the appropriate choice when the seated version is not available. A programme that includes both covers the hamstrings through different length-tension relationships for more complete development.
How much weight should I use for the lying hamstring curl?
Begin with a weight that allows 12 reps with full range of motion and a 2 to 3 second eccentric without the hips lifting. This is typically less than people expect. Increase by the smallest available increment when the full prescribed reps are achievable with good technique.
Can I do the lying hamstring curl with knee pain?
Depends on the cause of the knee pain. The lying hamstring curl loads the posterior knee structures (hamstring tendons, popliteus, posterior capsule) and is generally well-tolerated for anterior knee pain (patellofemoral pain). For posterior knee pain, Baker’s cyst, or popliteus tendinopathy, the lying curl may aggravate symptoms and a physiotherapy assessment should guide exercise selection. For ACL rehabilitation, the lying curl is introduced progressively based on graft healing timelines.
Is the lying hamstring curl useful for sprinters?
Yes, as one component of a complete hamstring programme. The lying curl develops the knee flexion function of the hamstrings, which contributes to the late swing phase of sprinting where the knee must flex rapidly against high eccentric hamstring loads. However, sprinters also need the hip extension function of the hamstrings (developed through RDLs and hip thrusts) and the eccentric hamstring strength at long muscle lengths (developed through Nordic curls). The lying curl is a useful but not sufficient standalone hamstring exercise for sprinters.