Cardiac response to exercise in normal-weight and obese, Hispanic men and women: implications for exercise prescription.

AIM

The effects of obesity on cardiac function during incremental exercise to peak oxygen consumption (VO(2peak)) have not been previously described. The purpose of this study was to compare submaximal and maximal cardiac function during exercise in normal-weight and obese adults.

METHODS

Normal-weight (n = 20; means ± SE: age = 21.9 ± 0.5 years; BMI = 21.8 ± 0.4 kg m(-2)) and obese (n = 15; means ± SE: age = 25.1 ± 5.2 years; BMI = 34.1 ± 01.0 kg m(-2)) participants were assessed for body composition, VO(2peak) and cardiac variables (thoracic bioimpedance analysis) at rest and at heart rates (HR) of 110, 130, 150 and 170 beats min(-1) and maximal HR during incremental cycling exercise to exhaustion. Differences between groups were assessed with mixed-model ancova with repeated measures. Cardiac variables were statistically indexed for body surface area and resting HR. VO(2) and arteriovenous oxygen difference (a-vO(2)) were statistically indexed for fat-free mass and resting HR.

RESULTS

Significant main effects for group indicated obese participants had higher cardiac output (Q) index and stroke volume (SV) index but lower ejection fraction (EF) and a-vO(2) index during incremental exercise to exhaustion compared with their normal-weight peers, despite similar submaximal and maximal VO(2) and absolute power outputs (P < 0.05).

CONCLUSIONS

Our findings suggest that although Q index and SV index were higher in obese, young adults, EF and a-vO(2) index were significantly lower when compared to matched, normal-weight adults.