Fig. 1

Study design. a A picture of the treadmill apparatus used in this study. b Schematic overview of the experimental protocol. Female Balb/cCrSlc mice were randomly divided into four groups. At 8 weeks of age, mice underwent OVX or SHAM surgery with 2 weeks for recovery. At 10 weeks of age, mice were subjected to a training period of forced running at 12 m/s for 10 min as an adaptation to treadmill running (5 days a week, gray circle). After the initial training period, “Run” groups were then subjected to forced running at 12 m/s for 10 min followed by 20 m/s for 100 min for 6 weeks (closed circle) and “Cage” groups were left in cage ad libitum (open circle). After 6 weeks of running or cage ad libitum, the uterus and both left and right knee joints were harvested. c Uterus weights were significantly decreased after OVX regardless of running. Values are means with SEM. Mann-Whitney’s U test was performed between the SHAM group (n = 15) and the OVX group (n = 20). Asterisk indicates p = 0.0002. d Body weights before and at sacrifice. Values are means with SEM. Differences among each group were assessed using a Kruskal-Wallis one-way analysis of variance by ranks followed by Steel -Dwass’s post-hoc test. Removal of ovary did not alter body weight significantly at 2 weeks after surgery (“10 week-old”, P = 0.59) and after forced running between the groups (“17 week-old”, P = 0.12). Number of mice in each group is indicated in the figure