Are Habitual Levels Or Changes In Accelerometer Measured Physical Activity Associated With Postpartum Weight Loss?

Postpartum weight retention is associated with future obesity and increased risks of chronic diseases. It is suggested that physical activity (PA) contributes to postpartum weight loss. However, there is a lack of evidence from accelerometer-measured PA over repeated time points. PURPOSE: This pilot study aimed to examine the association of accelerometer-measured PA and 8-week weight change in postpartum women. METHODS: Eight, 2-5 month postpartum women were provided a scale to weigh themselves at baseline and 8 weeks later. The participants wore an ActiGraph GT9X accelerometer on the non-dominant wrist for 24 hours, 7 consecutive days at both timepoints. Euclidean Norm Minus One (ENMO) algorithm was used to calculate mean acceleration (mg) and time in moderate-to-vigorous PA (MVPA, ENMO≥100 mg), using GGIR package in R software. The average PA (habitual PA) and the change in PA across the 8 weeks were quantified. Spearman’s correlation was used to examine the association between PA (both average and change in PA) with 8-week weight change. RESULTS: Mean weight at baseline was 86.1 ± 16.9 kg and weight change over 8 weeks was -0.1 ± 2.5 kg. Averaged across both visits, participants wore the accelerometer for 7.0 ± 0.7 days and 1251.0 ± 128.0 min/day. The average PA was 21.5 ± 5.3 mg acceleration and 66.7 ± 36.6 min/day of MVPA. Change in PA was 1.6 ± 5.7 mg acceleration and 1.4 ± 15.9 min/day of MVPA. There were significant inverse associations for 8-week PA averages for acceleration (r = -0.90, p = 0.002) and MVPA min/day (r = -0.90, p = 0.002) with weight change (Figure). There were no significant associations with 8-week changes in PA for acceleration (r = 0.12, p = 0.78) or MVPA min/day (r = 0.21, p = 0.61) with weight change. CONCLUSION: Higher habitual levels, but not change, in PA over eight weeks was associated with postpartum weight loss.