Association among physical activity level, cardiorespiratory fitness, and risk of musculoskeletal injury

To help public health practitioners promote physical activities with a low risk of injury, this study determined the relation among type and duration of physical activity, cardiorespiratory fitness, and musculoskeletal injury in a sample of adults enrolled in the Aerobics Center Longitudinal Study. Subjects included 4,034 men and 967 women who underwent a baseline physical examination between 1970 and 1985 and who returned a mailed follow-up surv ey in 1986. At baseline, a treadmill graded exercise test was used to measu re cardiorespiratory fitness. At follow-up, subjects reported injuries and type and duration of physical activity in the preceding 12 months. Polytomo us logistic regression was used to estimate the association among physical activity type and duration, cardiorespiratory fitness, and injury. The risk of sustaining an activity-related injury increased with higher duration of physical activity per week and cardiorespiratory fitness levels. Results s uggest that cardiorespiratory fitness may be a surrogate for unmeasured com ponents of physical activity, such as exercise intensity. Among walkers, in creasing duration of activity per week was not associated with an increased risk of injury. Results suggest that, for most adults, walking is a safe f orm of physical activity associated with a lower risk of injury than runnin g or sport participation.