Swelling of the knee joint: effects of exercise on quadriceps muscle strength

To investigate the effects of excessive fluid in the knee joint on the performance of the quadriceps muscles and to determine whether quadriceps muscle performance can be altered by exercising the swollen joint.

A before-after trial design was used, and the procedures were performed in a laboratory setting.

A random sample of 27 adult men with no musculoskeletal problems was divided into intervention and control groups.

First, in all groups, torque generated by the quadriceps muscle was examined by isokinetic muscle testing undertaken at a joint angular velocity of 120 degrees/sec over a range of motion from 5 degrees to 80 degrees flexion. After this initial test, in group 1, 60mL saline and dextrose was injected into the knee joint and subjects repeated the maximal effort procedure. Subjects then performed submaximal exercise for 3 to 4 minutes, after which maximal effort testing was undertaken again. In group 2, subjects received no injection of fluid, undertook 2 maximum effort tests, then performed submaximal exercise for 3 to 4 minutes, after which maximum effort testing was undertaken again. In group 3 (control group), subjects undertook three maximum effort tests over a time period similar to that for the other groups.

Quadriceps muscle torque generated at 60 degrees from full knee extension.

Torque decreased (p < .05) 30% immediately after the injection of fluid. However, torque returned to preinjection levels after submaximal exercise (p > .05). These findings were related to joint capsule compliance and fluid movement. No significant changes (p > .05) in torque were observed for the other two groups.

Submaximal exercise of swollen knee joints can decrease artificially induced quadriceps muscle inhibition. These findings may have implications for patients with perennial effusions who at times undertake gait activities.