Maximal ventilation and body size determine the oxygen cost of ventilation

Abstract

The oxygen cost of ventilation (VO2VENT) exponentially increases as ventilation increases, especially from moderate to maximal rates. PURPOSE The purpose of this study was to measure VO2VENT at maximal efforts using a relatively large number of subjects of different fitness levels, body sizes, and ages, and correlate subject characteristics (e.g., age, VO2max, body surface area (BSA), weight, height) with VO2VENT. We hypothesized that age and VO2max would correlate with VO2VENT at maximal exercise. METHODS 20 healthy, non-smoking male (n=18) and female (n=2) subjects (age: 21–43 yrs, VO2max: 2.2–7.0 l/min, weight: 50.8–113.6 kg) performed a cycle VO2max test and maximal ventilation (VEmax) was measured. Subjects mimicked their VEmax in a cycling posture while VO2VENT was measured. Since the VO2VENT data was not normally distributed, the log of VO2VENT was used as the dependent variable. Multiple regression was used to determine if subject characteristics could predict VO2VENT at maximal exercise. RESULTS BSA, body weight and mimicked VEmax were significantly correlated to VO2VENT, R2 = 0.797, F(2,17) = 30.843, SEE = −0.057, p < 0.001. The prediction equation indicated that BSA, body weight and mimicked VEmax were weighted the highest, the second and third highest, respectively, in predicting VO2VENT (Log of VO2VENT = 0.52037*(BSA) + 0.00096*(VEmax) – 0.00521*(Wt) – 1.12924). Age and VO2max were not significantly correlated to VO2VENT. CONCLUSION Although 79.7% of VO2VENT could be explained, the remaining unexplained between-subjects variability in VO2VENT warrants further research in this area.