Smart Workout Diary

Machine Single-Leg Extension

The machine single-leg extension is an isolation exercise performed one leg at a time on a leg-extension machine. It primarily trains the quadriceps through knee extension and can help build thigh strength, muscle control, and balanced development between legs.

Demonstration

Machine Single-Leg Extension — demonstration 1
Machine Single-Leg Extension — demonstration 2

Instructions

  1. Adjust the machine so the seat back supports your torso, the knee joint aligns with the machine pivot, and the lower pad rests just above the ankle.
  2. Select a manageable load, sit tall with your back against the pad, and secure the working leg behind the roller pad. Keep the non-working foot safely clear of the moving lever.
  3. Brace your torso, hold the handles, and begin with the working knee bent comfortably without forcing a deep bend.
  4. Extend the knee smoothly until the leg is nearly straight, keeping the thigh on the seat and avoiding a forceful lockout.
  5. Lower slowly back to the starting position with control. Complete the chosen repetitions, then set up and repeat on the other leg.
Muscle Group
Quads
Type
Strength
Mechanics
Isolation
Equipment
Machine Strength
Difficulty
Beginner

Technique tips

  1. Match the pivot carefully: poor knee-to-pivot alignment can make the movement feel uncomfortable and reduce control.
  2. Use a smooth tempo: lift without swinging and make the lowering phase deliberate.
  3. Keep your hips down: do not lift or slide your hips to move a heavier load.
  4. Train both sides evenly: use the same controlled range of motion and repetitions for each leg.
Exercise library