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The Role of Muscle Fatigue in Knee Injuries

Preventing injuries in athletes is a major goal of sports medicine research. In this study researchers look at the effect of muscle fatigue on knee ligament injuries. Fatigue leads to a loss of joint position sense called proprioception.

We know that reduced joint position sense leads to injury. We don't know what causes decreased joint proprioception. Is it a change in the receptors in the muscle? Receptors in the joint? Or is some other part of the proprioceptive pathway affected?

This study had two goals. The first was to measure the effects of two kinds of fatigue on knee joint proprioception. The second goal was to find out what part of the muscle control pathway changes with fatigue. The hope was to find ways to prevent knee ligament injuries caused by decreased proprioception from fatigue.

Twenty-seven healthy men ages 19 to 31 were studied. Local and general loads were applied. Local load was given by a device that resists knee motion. Local fatigue was measured using the speed of resisted knee motion. Running five minutes on a treadmill gave each man a general load. Heart rate was used to measure general fatigue.

The authors say results show that only general fatigue affects knee proprioception. Decreased proprioception occurred without a loss of muscle strength. This means that the cause of injury was some other factor besides local fatigue.

The authors suggest adding a new exercise element to endurance training. Neuromuscular training must be a part of a knee injury prevention program. This type of training works on muscle control in order to effect the nerves and the nerve sensors of the knee. The next step is to measure how long it takes to recover from general fatigue during exercise. This information may help decrease knee injuries in athletes.

References: Kazutomo Miura, MD, et al. The Effect of Local and General Fatigue on Knee Proprioception. In Arthroscopy. April 2004. Vol. 20. No. 4. Pp. 414-418.

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