🦵 Leg Curl Form Guide
Isolate hamstrings for powerful leg development.
SportsReflector AI analyzes your leg curl form by tracking key body landmarks such as the knee, hip, and ankle joints. We specifically monitor the knee joint angle throughout the concentric and eccentric phases, ensuring a full range of motion and controlled movement. Our AI also assesses hip stability and the absence of compensatory movements, providing a comprehensive score for optimal hamstring activation.
Primary Muscles
Hamstrings
Equipment
Leg Curl Machine
AI Score Categories
5 metrics tracked
What AI Analyzes in Your Leg Curl
SportsReflector tracks 5 key metrics to generate your 0–100 form score.
AI Form Score
Every Leg Curl session gets an overall form score plus category-level scoring for each metric above.
4 Leg Curl Mistakes AI Catches
These are the most common Leg Curl form errors — and the ones most likely to cause injury or limit your progress.
Jerking the weight up or allowing it to drop quickly on the eccentric phase reduces muscle tension and engagement. This can also place undue stress on the knee joint and lower back, increasing the risk of strain or injury due to uncontrolled forces.
Fix: Focus on a slow, controlled movement. Aim for a 2-second concentric lift and a 3-second eccentric lowering phase. Ensure the weight is appropriate for maintaining control throughout the entire repetition.
Allowing the hips to lift off the bench during the curl indicates that the weight is too heavy or the core is not engaged. This shifts the load from the hamstrings to the lower back and hip flexors, reducing hamstring isolation and potentially causing lower back discomfort or injury.
Fix: Reduce the weight to a manageable level. Actively press your hips and lower back into the pad throughout the entire movement. Engage your core to maintain a stable torso.
Not fully extending the legs at the start or not fully contracting the hamstrings by bringing the heels close to the glutes limits the muscle's work. This reduces the effectiveness of the exercise, preventing full hamstring development and strength gains.
Fix: Ensure your knees are fully extended (but not locked) at the start. Curl the weight until your heels are as close to your glutes as possible, achieving a peak contraction in the hamstrings.
Allowing the knees to splay outwards during the curl can indicate weak adductors or an attempt to recruit other muscles to assist the movement. This reduces the direct isolation of the hamstrings and can place awkward stress on the knee joint.
Fix: Keep your knees aligned with your hips and ankles throughout the movement. Imagine squeezing a ball between your knees to maintain proper alignment and hamstring focus.
Muscles Worked
Get Your Leg Curl Form Score
Record your Leg Curl on your iPhone and get an instant 0–100 AI form score with specific corrections for every mistake above.
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