Fig. 1

a Travel distance per week per group. Notice, the control group was exposed to a constant amount of exercise throughout the protocol, 150 m per week. For the other groups, there was a gradual increase in the amount of exercise from week 2 to week 5. From week 5 to the end of the intervention period, the levels of exercise were constant for rats in the MD and HD groups. For rats on the EHD group, the exercise distance doubled, tripled, and quadrupled in weeks 10, 11, and 12 compared to weeks 5–9, respectively. b Body fat. % body fat measured in the end of the experimental protocol. c Total modified Mankin scores: No significant differences were found between groups. MD moderate duration exercise, HD high duration exercise, EHD extra high duration exercise. * indicates significant difference when compared to control group. # indicates significant difference when compared to moderate duration group