KNEE
(LEG) EXTENSION
CORRECT FORM
1)
Assume a seated position on the knee extension machine as shown. Position
your back flat on the back pad and your buttocks flat on the bottom
pad. Position
your legs so that the roller pad contacts just above your foot.
Grasp the handles alongside of you.
2) Begin to
extend the knees while keeping your back and buttocks in the same
position.
3) Extend your
knees to the maximum position. Contract your quadriceps muscles
at the top of the movement.
4) Lower the
roller pad slowly and under control.
5) Inhale as
you lower the pad, exhale as you raise the roller up.
6) The knee
extension can also be done with one leg only. In this case, leave
the opposite leg bent.
MUSCLES
USED
SAFETY
CONSIDERATIONS/PRECAUTIONS
The
main safety issue to consider with the knee extension is being sure
that you are sitting all the way back. Allowing yourself to shift
forward is a compensation you will make to offset the weight being
lifted. This will only share the workload with the lower back by changing
the mechanical advantage of the quadriceps.
EFFECTIVENESS
The knee extension
is an effective exercise for shaping of the quadriceps muscles. This
is one of the more popular exercises in the gym.
For bodybuilders,
this exercise is essential because of its importance in isolating
the quadriceps muscle.
For other athletes
however, there are some risks to be weighed. First, understand that
your quadriceps do not work in this manner during any sports. There
is little functional carryover to standing. Typically, the quadriceps
is responsible for decelerating the knee joint during running, jumping,
planting, pivoting, etc. Or, the quadriceps acts in a power-move
to push the body forward. This exercise will not improve any of
those aspects of sports performance, because of the position you
are training in.
More importantly,
studies show that few activities - not walking, running, jogging,
squats, stairs, etc. - place more stress on the anterior cruciate
ligament (ACL) than does resisted knee extension.(1)
Given
that athletes in many sports, especially skiing, basketball and
football, are more likely to sustain an ACL tear, the use of this
exercise as a training tool for athletes should definitely be questioned.
HELPFUL
WITH TRAINING FOR
Bodybuilding.
REFERENCES
1.
Parker MG: Biomechanical and histological concepts in the rehabilitation
of patients with anterior cruciate ligament reconstructions. JOSPT
July 1994, 20(1):44-50.
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