68-LB: Being Physically Active Does Not Rescue Skeletal Muscle Microvascular Dysfunction in Overweight Individuals

Skeletal muscle microvascular blood volume increases after a meal to increase glucose and insulin delivery to the muscle. In obese individuals this microvascular action in muscle is lost (Keske et al. 2009 Diabetes Care). However, exercise training can improve muscle microvascular responses in the postprandial state (Russell et al. 2017 Diabetes Care). We hypothesized that people who are overweight but are habitual exercisers would have similar increases in microvascular perfusion following a mixed meal as people who are lean and exercise regularly. Methods: Nine lean (LEAN+Ex, BMI < 23 kg/m2) and five overweight (OW+Ex, BMI > 27 kg/m2) physically active participants (> 75 min of vigorous intensity or > 150 min of moderate intensity exercise per week) were recruited. Body composition was assessed by DEXA. After an overnight fast, participants underwent a mixed meal challenge (1214 kJ). Thigh muscle microvascular responses were assessed by contrast-enhanced ultrasound at rest and 1 hour after the mixed meal. Results: Data are presented in Table 1 (Mean ± SE, * p<0.05 vs. LEAN+Ex; + p<0.05 vs. resting). Conclusion: The postprandial increase in microvascular blood volume in the Lean+Ex group was not observed in the OW+Ex group. These data suggest that habitual exercise is not sufficient to overcome the negative effects of being overweight on muscle microvascular responses to a mixed meal. Disclosure A.C. Betik: None. D.J. Morrison: None. L. Parker: None. K. Roberts-Thomson: None. M. Keske: None. Funding Institute for Physical Activity and Nutrition