EFFECT OF ANTERIOR CRUCIATE LIGAMENT DEFICIENCY ON ECONOMY OF WALKINGAND JOGGING

The metabolic cost of walking and jogging following injury to the ante rior cruciate ligament is unknown. Economy of motion refers to the oxy gen consumption for a submaximal work rate. The purpose of this study was to compare the economy of walking and jogging of an anterior cruci ate ligament-deficient population with that of a control population wi thout orthopaedic abnormalities. Steady-state oxygen consumption was m easured in 30 patients and 98 controls while they were on a treadmill at various speeds. Deficiency of the anterior cruciate ligament was di agnosed arthroscopically. The patients also were tested for isokinetic knee extension-flexion strength, hip flexion, and abduction and adduc tion strength and underwent arthrometric measurement of anterior tibia l 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 defici ency on economy at the other speeds tested. The patients had significa nt deficits in strength of all muscle groups tested. Steady-state oxyg en consumption at 160.9 m/min tended to be inversely related to the de ficit of strength of knee flexion (r = -0.44, p = 0.07). Arthrometric measurements and chronicity of injury were unrelated to steady-state o xygen consumption. These data indicate that anterior cruciate ligament deficiency increases oxygen consumption during jogging. In long-dista nce running, this decreased economy translates into significant additi onal caloric requirements, which may result in earlier fatigue.