The impact of high BMI on acute changes in body composition following 90 min of running

Objectives: Although physical activity ameliorates the metabolic impact of high body mass index (BMI), runners with BMI ≥25 kg/m2 are relatively understudied. This study had two goals: (1) to identify differences in body composition, as measured by dual X-ray absorptiometry (DXA), between overweight (BMI ≥ 25 kg/m2) runners (OWR) and normal weight (BMI < 25 kg/m2) runners (NWR) and (2) to examine whether a 90-min run alters total or regional fat mass, as measured by DXA, in OWR and NWR. We hypothesized that OWR would have higher total body fat than NWR and OWR with greater changes in visceral fat after a prolonged run. Design: Body composition analysis before and after a supervised run. Methods: We recruited NWR (n = 16, F: n = 7, 28.1 ± 1.4 years, BMI 22.0 ± 0.4 kg/m2, results as mean ± SE) and OWR (n = 11, F: n = 7, 32.0 ± 1.6 years, BMI 30.5 ± 1.4 kg/m2) participants. DXA-based body composition was measured before and after a supervised, 90-min run at 60% heart rate reserve. Results: OWR had higher body fat than NWR in all measured regions. Both groups did not significantly reduce fat mass at any measured fat depots after the running exposure. Conclusions: OWR had higher body fat in all measured regions than NWR. DXA could not demonstrate any acute fat mass changes after a prolonged run.