Poor compensatory hyperventilation in morbidly obese women at peak exercise.
This study was designed to compare differences in pulmonary gas exchange at rest and at peak exercise in two groups of women: (1) physically active, non-obese women and (2) women with morbid obesity. Fourteen morbidly obese women (body mass index or BMI=49+/-7 kg/m2; peak oxygen consumption or VO2 peak=14+/-2 ml/(kg min)) and 14 physically active non-obese women (BMI=22+/-2 kg/m2; VO2 peak=50+/-6 ml/(kg min)) performed an incremental, ramped exercise test to exhaustion on a cycle ergometer. Arterial blood was sampled at rest and at peak exercise. At rest, the alveolar to arterial oxygen partial pressure difference was 3x higher in the obese women (14+/-10 mmHg) compared to non-obese women (5+/-4 mmHg). Arterial carbon dioxide pressure (PaCO2) was identical in both groups at rest (37+/-4 mmHg). Only the non-obese women showed a decrease in PaCO2 rest to peak exercise (-5+/-3 mmHg). The slope between heart rate and VO2 during exercise was higher in the morbidly obese compared to non-obese women indicating that for the same absolute increase in VO2 a larger increase in heart rate is needed, demonstrating poorer cardiac efficiency in obese women. In conclusion, morbidly obese women have poorer exercise capacity, cardiac efficiency, and compensatory hyperventilation at peak exercise, and poorer gas exchange at rest compared to physically active, non-obese women.
Zavorsky
Gerald S
GS
Department of Obstetrics, Gynecology and Women's Health, Saint Louis University School of Medicine, Saint Mary's Health Center, 6420 Clayton Road, Room 290, St. Louis, MO 63117, United States. zavorsky@slu.edu
Murias
Juan M
JM
Kim
Do Jun
DJ
Gow
Jennifer
J
Christou
Nicolas V
NV
D000328:Adult; D001784:Blood Gas Analysis / Q000379:methods; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006985:Hyperventilation / Q000503:physiopathology*; D008875:Middle Aged; D009767:Obesity, Morbid / Q000503:physiopathology*; D010101:Oxygen Consumption / Q000502:physiology*; D010313:Partial Pressure; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D012146:Rest / Q000502:physiology