Legs / Beginner / Isolation (single joint)

Single-Leg Leg Extension

A machine isolation exercise for the quads.

At a glance

Primary

Quads

Equipment

Machines

Movement pattern

Knee extension

Level

Beginner

Type

Legs, Isolation (single joint), One side at a time, Balance / unstable

Loads the knee. Use a load you can control and skip it if it causes pain.

How to do it

1. Seat yourself in the machine and adjust it so that you are positioned properly. The pad should be against the lower part of the shin but not in contact with the ankle. Adjust the seat so that the pivot point is in line with your knee. Select a weight appropriate for your abilities.
2. Maintaining good posture, fully extend one leg, pausing at the top of the motion.
3. Return to the starting position without letting the weight stop, keeping tension on the muscle.
4. Repeat for the desired number of repetitions.

Common mistakes

• ✗ Swinging heavy weight with momentum.

  Why it hurts: The shin pad acts as a long lever on the knee; jerky reps load the patellar tendon and the joint behind the kneecap.

  ✓ Instead: Use a weight you can lift in 2 seconds and lower in 3, and pause at the top.

• ✗ Machine not adjusted to your body.

  Why it hurts: If the knee is not in line with the machine's pivot, the joint shears as it moves.

  ✓ Instead: Line the knee up with the pivot point and set the pad just above the ankle.

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