Physical Activity and Sedentary Behavior Differ by Sex during the First 6 Months after Anterior Cruciate Ligament Reconstruction.

Introduction/purpose: Females have lower physical activity (PA) levels and inferior outcomes compared with males following formal rehabilitation after anterior cruciate ligament (ACL) reconstruction. This observational study aimed to determine if PA levels and sedentary behavior change and vary by sex during the time before and 6 months after ACL reconstruction.

Methods: PA and sedentary behavior were measured in an observational cohort of 30 participants (19.6 ± 4.9 yr old, 66.7% female) using a three-axis accelerometer before (preoperative) and at 2, 4, and 6 months after ACL reconstruction. Daily steps, daily minutes of moderate to vigorous PA (MVPA), and percentage of wake time in sedentary behavior (%SED) were measured. Two-by-four (sex-time) repeated measures analyses of variance were used to test changes in PA and %SED.

Results: In females and males, daily steps and MVPA increased from 2 to 4 months after ACL reconstruction (all P < 0.05) but not between other consecutive time points. %SED did not change between any consecutive time points. At 6 months, females walked fewer daily steps ( P = 0.002; females: 7003 ± 2068; males: 10,406 ± 3277), spent fewer minutes in MVPA ( P = 0.010; females: 31.3 ± 14.6; males: 54.9 ± 32.4), and spent more time in %SED ( P = 0.003; females: 67.9 ± 7.4; males: 57.5 ± 9.5).

Conclusions: PA levels increased in females and males from 2 to 4 months after ACL reconstruction but not between other consecutive time points from before through 6 months after surgery. Females completed less PA and spent more time in sedentary behavior than males and may require greater monitoring to improve PA after ACL reconstruction. The disparity in PA and sedentary behavior across sex follows consistent previous findings that outcomes after ACL reconstruction are poorer in females compared with males.