Effect of anterior cruciate ligament deficiency on economy of walking and jogging.

The metabolic cost of walking and jogging following injury to the anterior cruciate ligament is unknown. Economy of motion refers to the oxygen consumption for a submaximal work rate. The purpose of this study was to compare the economy of walking and jogging of an anterior cruciate ligament-deficient population with that of a control population without orthopaedic abnormalities. Steady-state oxygen consumption was measured in 30 patients and 98 controls while they were on a treadmill at various speeds. Deficiency of the anterior cruciate ligament was diagnosed arthroscopically. The patients also were tested for isokinetic knee extension-flexion strength, hip flexion, and abduction and adduction strength and underwent arthrometric measurement of anterior tibial displacement. The patients had a statistically significant increase in oxygen consumption when jogging at 160.9 m/min (p = 0.007); however, there was no significant effect of anterior cruciate ligament deficiency on economy at the other speeds tested. The patients had significant deficits in strength of all muscle groups tested. Steady-state oxygen consumption at 160.9 m/min tended to be inversely related to the deficit of strength of knee flexion (r = -0.44, p = 0.07). Arthrometric measurements and chronicity of injury were unrelated to steady-state oxygen consumption. These data indicate that anterior cruciate ligament deficiency increases oxygen consumption during jogging. In long-distance running, this decreased economy translates into significant additional caloric requirements, which may result in earlier fatigue.