Fig. 9.
Exercise improved postfracture locomotor activity and reduced anxiety. Fracture mice were treated with 4 weeks of wheel running (FX + wheel, week 7) or no wheel access (FX + no wheel, week 7); nonfracture mice with and without access to running wheels were used as controls (control + wheel, control + no wheel, week 7). In an additional set of experiments, fracture and control mice were given 4 weeks of wheel access and then the wheel was removed for 2 weeks (FX + wheel, control + wheel, week 9) or were not given access to a running wheel and were tested at 9 weeks postfracture (FX + no wheel, week 9). In the open-field test, compared to nonfracture controls, there was no reduction in the distance traveled by the fracture + no wheel cohort at 7 (A) or 9 (B) weeks postfracture. Wheel exercise (FX + wheel) did increase the distance traveled, compared to fracture + no wheel (A), but this effect was lost after stopping exercise for 2 weeks (B). The exercise fracture mice spent increased time in the center of the open-field assay, compared to no exercise fracture mice or controls (C), but this effect was lost after stopping exercise for 2 weeks (D). After 4 weeks of wheel exercise, control nonfracture mice also spent increased time in the center of the open-field assay, compared to controls lacking wheel access, and this effect was also lost after stopping exercise for 2 weeks (D). Compared to no fracture controls, the fracture + no wheel mice were less likely to enter the open arms of the zero-maze assay; this behavior signifies increased anxiety at 7 (E) and 9 (F) weeks postfracture. Four weeks of wheel exercise reversed anxiety behavior in the zero-maze test in fracture mice (FX + wheel) but had no effect on controls (E); this anxiolytic effect was lost after stopping exercise for 2 weeks (F). Exercising the fracture mice caused an increase in the time spent in the open arms of the zero maze (E), but this effect was lost after stopping exercise for 2 weeks (F). Values are means ± SD, n = 11 to 15 per cohort. One-way ANOVA with Bonferroni post hoc testing. *P < 0.05 and **P < 0.01 for fracture + no wheel or fracture + wheel versus control; #P < 0.05 and ##P < 0.01 for fracture + wheel versus fracture + no wheel; &&P < 0.01 for fracture + wheel versus control + wheel.