Figure 1: Experimental timeline (in days) for study assessing physical activity differences in C57BL/6J mice under various circulating sex steroid levels including normal physiological levels at baseline, low levels during gonadectomy phase, and elevated levels during replacement phase. Baseline, gonadectomy, and replacement indicate periods when wheel running activity was measured. Dark black bars indicate the recovery periods immediately following the gonadectomy surgery (beginning of day 8) and silastic capsule implantation surgery (beginning of day 24).