Leg Extension & Curl Machines

Leg Extension and Curl Machines: Isolate the Quads and Hamstrings

A leg extension machine seats the user with a pad across the shins and loads the quads as the knee straightens. A leg curl machine does the opposite, loading the hamstrings as the knee bends. They are the two isolation pieces every leg session ends on, and the ones most often paired on a single frame.

Seated, Prone or Kneeling Leg Curls

The seated leg curl keeps the hip flexed, which stretches the hamstrings and lets them take more load. The prone (lying) curl works face down with a straight hip and is the easiest to teach. The kneeling curl trains one leg at a time standing, and needs the least floor space. Which one a combination machine carries decides its curl position, so check that before comparing prices.

Plate-Loaded or Selectorized

Selectorized extensions and curls hold resistance evenly through the whole arc and change weight by pin, which is why gym buyers almost always choose them. Plate-loaded versions cost less and take standard plates, and for a home gym that is usually the deciding factor. A dual-function machine that does extension and curl from one seat is the common home choice; commercial floors run separate pieces so two members can train at once.

How to Use a Leg Extension Machine

Set the back pad so the knee joint lines up with the machine pivot and the shin pad sits just above the ankle. Extend until the legs are straight, hold for a count, and lower slowly. On the curl, pull the heels toward the glutes without lifting the hips off the seat. Three sets of 10 to 15 reps on each; these are not movements to load heavy and fast.