Isokinetic Strength Training Of The Hemiparetic Knee

Hemiparesis is weakness on one side of the body. This is frequently the result of a stroke but is less serious than hemiplegia, which is total paralysis of one side of the body. Because of the reduction in motor control often associated with hemiparesis, it can be difficult or impossible to use traditional strength-training exercises to rebuild strength. Isokinetic strength training is one way to address this problem.

Method

An isokinetic strength-training machine allows a physical therapist to control the precise range of motion to be worked by entering specifications into the machine's computer. It also allows for control over the level of resistance and the speed of the exercise. To reduce contributions from complementary muscles and effectively isolate the knee flexors and extensors, the machine provides stabilization for the patient in the form of a contoured seat that is adjustable to ensure appropriate support for a variety of body sizes and types.

Hamstrings

The hamstrings are the group of muscles on the back of the thigh that empower flexion at the knee joint, which can also be thought of as bending the knee. For isokinetic training of this muscle function, you sit on the machine with your extended leg strapped to the top of a resistance bar. The therapist enters the specifications regarding range of motion and speed into the machine, and you pull down on the resistance bar to bend your knee.

Quadriceps

The quadriceps are the group of muscles on the front of the thigh that power extension at the knee joint, or extending the leg at the knee. This is the opposite of what the hamstrings do, so as you might suspect, the isokinetic exercise is the opposite as well. Still in the seated position, you now have your bent leg strapped to the underside of the resistance bar. After the therapist enters the appropriate settings, you push up on the bar to extend your leg.

Effectiveness

A 1997 study by Shelley Sharp and Brenda Brouwer directly addressed the effects of isokinetic strength training of the hemiparetic knee and noted that this type of training has been shown to result in increased strength and improved gait, or walking ability. According to a 2006 study by H. Coury and others in the online journal "Gait and Posture," this type of training has gotten similarly good results for patients who have had surgery to repair an anterior cruciate ligament, or ACL. Coury says that more research needs to be done regarding possible harm to ACL patients due to shear stresses that may have been placed on the knees of patients in his study.