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How to Do the Leg Extension Exercise

Work the Quadriceps with the Leg Extension


Updated May 01, 2014

The leg extension exercise is popular for muscles of the front of the thighs -- the quadriceps including the rectus femoris and vastus muscles. The machine version uses a lever machine with a padded front bar which is pushed upward with extended legs. Some authorities are critical of this exercise because it traps the knee joint in one path, which, they say, could lead to injury. Even so, the exercise is widely used in knee/thigh rehabilitation with light weights and monitored repetitions.

If you need more general guidance on weight training, please refer to the beginner's guide.

1. How to Do the Leg Extension Exercise - Setup and Movement

leg extension
Photo (c) Paul Rogers & Cooloola Fitness
  1. Sit on the padded seat provided. (See image.)
  2. Initially, select a light weight from the stack.
  3. Hook the feet under the bar. Adjust the bar so that it rests comfortably at the lower end of the leg.
  4. If the machine in your gym does not have leg length adjustment, don't use it because an uncomfortable position might cause undesirable forces in the exercise movement.
  5. When set, choose a weight that enables you to extend the legs straight with effort but not too much strain. Don't use this exercise to test your maximum leg strength for example.
  6. Hold the head steady, grip the bars firmly at each side. Brace and breathe out on exertion and in on recovery.
  7. Do 2 to 3 sets of 8 to 12 repetitions each.

2. How to Do the Leg Extension Exercise - Points to Note

Leg extension
Photo (c) Paul Rogers & Cooloola Fitness
  1. Make sure your back is pushed back firmly against the back rest, particularly at the base of the spine.
  2. Keep the head and neck still on the leg extension. Don't wobble forward, back or to the sides.
  3. Don't use very heavy weights for this exercise. Keep the load light to moderate.
  4. Adjust the leg bar length appropriately so that the padded bar is not too far up the shins.
  5. Don't do this exercise if your knees hurt during the process.
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