EFFECTS OF A FUNCTIONAL KNEE BRACE ON LEG MUSCLE FUNCTION

The effects of a functional knee brace on local intramuscular pressure s and on calculated blood perfusion pressure in the tibialis anterior muscle of the legs of six volunteers were determined. Torque generatio n during dorsiflexion of the ankle joint was measured with a Kinetic C omputerized ergometer, and the time to elicit muscle fatigue during ex ercise was recorded. For each experimental subject studies compared ri ght with left unbraced legs, then right braced with left unbraced legs , and finally right unbraced with left braced legs. In the braced leg, intramuscular pressure at rest and muscle relaxation pressure during exercise were significantly higher, and the time to elicit muscle fati gue was 35% shorter. The calculated local blood perfusion pressure was lower because of the increased muscle relaxation pressure. We conclud e that the increased muscle relaxation pressure during exercise caused by a knee brace is a possible explanation for the premature developme nt of muscle fatigue in the braced leg.