Ventilatory response of moderately obese women to submaximal exercise
Babb, T.G.; Korzick, D.; Meador, M.; Hodgson, J.L.; Buskirk, E.R.
International Journal of Obesity 15(1): 59-65
1991
ISSN/ISBN: 0307-0565 PMID: 2010259 Document Number: 382796
To investigate the effect of moderate obesity on ventilatory responses to graded exercise, the ventilatory responses of 10 moderately obese (35+or-5% body fat) and 9 leaner women (22+or-2% body fat) were compared during walking on a treadmill with incremental increases in percent grade. Speed remained constant at 3.0 mph. In obese women, VO2 in litre/min and ml fat free weight-1 min-1, fb (breaths/min), VE (litres/min), and heart rate (HR) were greater (P<0.05) at all 4 absolute workloads. At 10.0 and 12.5% grade, VO2 (mg kg-1 min-1) was smaller and VE/VO2 was greater in the obese women. The difference in VE/VO2 suggests a lower ventilatory threshold for the obese women. Percent VO2 max and R (VCO2/VO2) were significantly different at 12.5% grade only. When VO2 was divided by HR (oxygen pulse), the 2 groups were not significantly different at any of the 4 workloads tested. The groups were compared further at workloads representing about 55, 65, 75, and 85% VO2max. HR was not significantly different at any of the 4 relative exercise intensities. VE was greater in the obese at 85% of maximum only (P<0.05) and fb was significantly greater at 55, 75, and 85% of maximum. Whereas cardiorespiratory responses of moderately obese women were increased at absolute workloads when compared to that of leaner women, HR was similar at comparable intensities of exercise. VE was also similar at comparable intensities of exercise below ventilatory threshold but fb was greater. The effect of the higher fb on exercise tolerance is unknown. The higher fb may be related to a decreased chest wall compliance in the moderately obese women.