Physical Activity and Sedentary Behavior Differ by Sex During the First Six Months after Anterior Cruciate Ligament Reconstruction

ABSTRACT Introduction/Purpose Females have lower physical activity (PA) levels and inferior outcomes compared to 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 prior to and six months after ACL reconstruction. Methods PA and sedentary behavior were measured in an observational cohort of 30 participants (19.6 ± 4.9 years old, 66.7% female) using a 3-axis accelerometer before (Pre-Op) and at two, four and six 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-by-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 two to four 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 six 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 two to four months after ACL reconstruction but not between other consecutive time points from before through six 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 to males.