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Distinguishing Characteristics of the Responses to Incremental Exercise in 1,356 Overweight or Obese Subjects

Cooper, Christopher B. FACSM1; Sowash, James2; Black, John W.2; Taylor, Michael S.2; Hove, Jason A.1; Storer, Thomas W.1

Medicine & Science in Sports & Exercise: May 2004 - Volume 36 - Issue 5 - p S141
Annual Meeting Abstracts: D-15 – Free Communication/Slide: Exercise and Obesity

1David Geffen School of Medicine at UCLA, Los Angeles, CA.

2Viasys Healthcare Inc, Yorba Linda, CA.



Purpose: Excess body weight affects the human response to incremental exercise testing (XT). In particular, this creates difficulty in assessing whether aerobic performance is normal. We set out to characterize the response to XT in a large number of overweight or obese subjects, to evaluate prediction equations for maximum oxygen uptake (VO2max), and to examine the hypothesis, derived from clinical experience, that obesity is associated with chronotropic insufficiency during exercise. Methods: A database containing anonymous results from 1684 XT was examined. These tests were submitted over 7 months by a network of providers performing office based XT. We identified 1,356 subjects with excess body weight: 569 were overweight (OW = BMI 25–29), 674 were obese (OB = BMI 30–39) and 113 were morbidly obese (MO = BMI ≥40). Their XT responses were analyzed using novel algorithms that examined VO2max, functional exercise capacity (VO2max, ml/kg/min), metabolic threshold (VO2mt), chronotropic index (CI = fCmax-fCrest/VO2max-VO2rest). Reference values for VO2max were derived using (A) age, height and ideal body weight, and (B) age, height and actual body weight (Cooper and Storer, 2001). Results: Mean (SD). Significantly different by ANOVA: *P < 0.01



Conclusion: We analyzed the responses to XT in a large number of overweight and obese subjects. We demonstrated progressive functional impairment with increasing obesity despite apparently normal aerobic capacity. We validated use of actual body weight in prediction equations for VO2max. We also showed falsely high metabolic thresholds and systematic reductions in chronotropic index with increasing obesity. The CI was below the lower limit of normal in the morbidly obese. Supported by: Viasys Healthcare Inc

©2004The American College of Sports Medicine