Changes in body composition and bone density in response to HIIT. Body fat percentage (A) and lean body mass (B) were measured in mice at baseline, after 4-weeks, and after 8-weeks (endpoint) of HIIT (n = 14) or remaining sedentary (SED, n = 11), using quantitative magnetic resonance (qMR). At endpoint, bone mineral density (BMD) was assessed using DEXA (C), SED n = 7, HIIT n = 11, * indicates p < 0.05.