Background: Associations between physical activity and injuries have been previously examined using self-reports. The present investigation examined this association using objective measures of activity and injury.
Methods: To quantify ambulatory activity, pedometers were worn daily by recruits in 10 Army Basic Combat Training companies during the 9-week training cycle. Injuries were obtained from a medical surveillance system, defined as traumatic or overuse events resulting in a medical care provider visit. A daily questionnaire documented whether or not recruits wore the pedometers and trained with their companies for the entire day.
Results: Training companies were categorized by activity level into 3 groups with higher activity (HA, 17,948±550 steps/day), 4 with moderate activity (MA, 16,346±768 steps/day) and 3 with lower activity (LA, 14,772±400 steps/day). Among men, the MA and HA groups were at 1.52 (95% confidence interval [95% CI]=1.15-2.01) and 1.94 (95% CI=1.46-2.61) times higher injury risk, respectively, compared with the LA group. Among women, the MA and HA groups were at 1.36 (95% CI=1.07-1.73) and 1.53 (95% CI=1.24-1.89) times higher injury risk, respectively, compared with low LA group. The relationships remained significant after considering physical characteristics and physical fitness.
Conclusions: In consonance with previous self-report studies, higher physical activity was associated with higher injury risk.