Postpartum physical activity (PA) is an important component of the woman's health. Recently, more attention has been paid to develop guidance for safe return to PA after delivery, including return to running. Little is known about when women start PA after delivery and what type of PA they are practicing. The objectives were to (1) describe early postpartum PA (≤6 weeks), (2) compare women's characteristics between those who started any kind of PA and those who did not, and those who started and did not start running, and (3) explore predictors of PA and running. Ninety-one women, who were part of a longitudinal cohort study, were included. At 6 weeks postpartum, PA was assessed using a questionnaire. Predictors of PA and running were age, education, parity, pre-pregnancy body mass index, prenatal PA, gestational weight gain, prematurity, delivery mode, season, and breastfeeding. The Wilcoxon rank-sum test, Fischer's exact test, and logistic regression analyses were used. Eighty-five women (93%) resumed PA by 6 weeks postpartum. Walking was practiced by 92% of women for 127.0 ± 81.3 min/week. Running was the second most popular activity, practiced by 11% of women for 57.5 ± 31.8 min/week. Walking and running were started around 2.0 and 3.6 weeks after delivery, respectively. Women who delivered in spring or summer were more likely to resume PA by 6 weeks postpartum, and those who ran while pregnant had five-fold higher odds of starting to run by 6 weeks postpartum (OR:5.03, 95%CI 1.27
19.92). These findings improve our understanding of PA practice, including running, in early postpartum.