1. Sit on machine and place ankles under the roller pads.
2. Raise legs upward until knees are straight.
3. Lower legs back down to start position, knees bent 90 degrees.
Foot position: Pointing your toes directly upward (a) hits all sections of the quadriceps equally. Pointing your toes inward (b) internally rotates the tibia to target the inner quad “teardrop” (vastus medialis). Pointing your toes outward (c) externally rotates the tibia to hit the outer quad (vastus lateraJis).
Foot spacing: There isn’t much space on the roller pads to adjust foot spacing, but placing your feet close together will tend to target the outer quad, and a wider spacing will focus a little more on the inner quad.
Body position: Adjust the backrest so that the back of your knee fits snugly against the front edge of the seat and your whole thigh is supported. Leaning your torso backward or raising your buttocks off the seat extends the hip joint stretching the rectus femoris, making this section of the quad work harder during the exercise.
Range of motion: The arc of motion should be approximately 90 degrees. Forcibly contract the quadriceps at the top when the knees are fully straight. To avoid excess stress on the patella (kneecap), do not bend the knees beyond 90 degrees.
Resistance: Resistance is fairly uniform, but on many new machines the resistance increases slightly as the weight is raised up. less resistance at the start position minimizes stress across the kneecap with the knee bent.
One-leg extension: Performing this exercise one leg at a time improves focus. The unilateral leg extension is particularly useful for improving thigh asymmetry or aiding in rehabilitation when one leg is injured.