The effect of exercise intensity on endothelial function in physically inactive lean and obese adults.
OBJECTIVE
To examine the effects of exercise intensity on acute changes in endothelial function in lean and obese adults.


METHODS
Sixteen lean (BMI <25, age 23 ± 3 yr) and 10 obese (BMI >30, age 26 ± 6 yr) physically inactive adults were studied during 3 randomized admissions [control (C, no exercise), moderate-intensity exercise (M, @ lactate threshold (LT)) and high-intensity exercise (H, midway between LT and VO2peak) (30 min)]. Endothelial function was assessed by flow-mediated dilation (FMD) at baseline and 1, 2, and 4 h post-exercise.


RESULTS
RM ANCOVA revealed significant main effects for group, time, and group x condition interaction (p<0.05). A diurnal increase in FMD was observed in lean but not obese subjects. Lean subjects exhibited greater increases in FMD than obese subjects (p = 0.0005). In the obese group a trend was observed for increases in FMD at 2- and 4-hr after M (p = 0.08). For lean subjects, FMD was significantly elevated at all time points after H. The increase in FMD after H in lean subjects (3.2 ± 0.5%) was greater than after both C (1.7 ± 0.4%, p = 0.015) and M (1.4 ± 0.4%, p = 0.002). FMD responses of lean and obese subjects significantly differed after C and H, but not after M.


CONCLUSIONS
In lean young adults, high-intensity exercise acutely enhances endothelial function, while moderate-intensity exercise has no significant effect above that seen in the absence of exercise. The FMD response of obese adults is blunted compared to lean adults. Diurnal variation should be considered when examining the effects of acute exercise on FMD.
Department of Human Services, University of Virginia, Charlottesville, Virginia, United States of America.
Rachel
R
Hallmark
Department of Public Health Sciences, University of Virginia, Charlottesville, Virginia, United States of America.
James T
JT
Patrie
Department of Medicine, University of Virginia, Charlottesville, Virginia, United States of America.
Zhenqi
Z
Liu
Department of Human Services, University of Virginia, Charlottesville, Virginia, United States of America.
Glenn A
GA
Gaesser
Department of Medicine, University of Virginia, Charlottesville, Virginia, United States of America ; General Clinical Research Center, University of Virginia, Charlottesville, Virginia, United States of America.
Eugene J
EJ
Barrett
Department of Human Services, University of Virginia, Charlottesville, Virginia, United States of America ; Department of Medicine, University of Virginia, Charlottesville, Virginia, United States of America ; General Clinical Research Center, University of Virginia, Charlottesville, Virginia, United States of America.
Arthur
A
Weltman
D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D002940:Circadian Rhythm; D004730:Endothelium, Vascular / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000378:metabolism / Q000503:physiopathology; D012039:Regional Blood Flow / Q000502:physiology; D013851:Thinness / Q000378:metabolism / Q000503:physiopathology; D014664:Vasodilation / Q000502:physiology; D055815:Young Adult