Cardiac response to exercise in young, normal weight and overweight men and women.

Overweight and obesity are associated with hemodynamic changes at rest. Whether these changes are mirrored during exercise is uncertain. We compared cardiac output (Q) and stroke volume (SV) in 12 overweight (OW) and 12 normal weight (NW) adults at rest and during exercise. Participants were assessed for body composition, peak oxygen consumption, and Q and SV at rest and during cycling exercise at 50, 75 and 100 W. Cardiac output was significantly higher at rest and during exercise in OW than NW when fat mass and ethnicity were used as covariates. When fat free mass was added as a covariate, Q was no longer different between groups. Stroke volume tended to be higher in OW than NW when fat mass and ethnicity were used as covariates (P = 0.055) with no differences in heart rate observed. Although the total change in Q and SV was similar between groups with each exercise intensity, overall Q was higher in the OW than NW participants. The higher Q is likely explained by a higher SV, secondary to a greater blood volume in the OW. The elevated hemodynamic response in OW may reflect the early cardiac adaptations of excess body mass.