Exercise guide · Legs & Glutes

Machine Single-Leg Leg Extension

The Single-Leg Leg Extension (Machine) extends one knee at a time against the machine roller. The nonworking leg stays clear, unlike the standard bilateral leg extension.

Targets: Quads
Equipment: Machine
Type: Isolation

Step by step

How to do the Machine Single-Leg Leg Extension

Adjust the backrest, knee pivot, and shin roller so the working knee aligns with the machine axis and the pad rests above the ankle.
Sit fully against the back pad, grip the handles, and keep the nonworking leg safely away from the roller.
Extend the working knee until the leg is nearly straight without lifting the hips or locking forcefully.
Pause while the quadriceps contracts and the thigh remains on the seat.
Lower the roller slowly to a comfortable bend, complete the set, and reposition for the other leg.

Form cues

Use one leg only
Align knee with pivot
Keep thigh on the seat
Lower the roller slowly

Common mistakes

Helping with the nonworking leg
Misaligning the knee with the machine pivot
Lifting the hips to finish the extension
Dropping the roller rapidly into deep knee flexion

Muscles worked

Primary

Quads

Secondary

None significant

Safety: Use substantially less load than for bilateral extensions, set the machine axis carefully, and avoid forceful knee lockout. Stop for sharp kneecap, knee-joint, or hip pain.

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