T. Takken;  H. J. Hulzebos;

ObjectiveThe purpose of the present study was to investigate the association between cardiorespiratory fitness (CRF) measured as peak oxygen uptake (VO2peak, expressed in mL/min) and body mass index (BMI) in a large cohort of apparently healthy subjects.
MethodsBMI and VO2peak were measured in a cross-sectional study of 8470 apparently healthy adults. VO2peak (mL/min) was determined by an incremental cycle ergometer test to exhaustion. Linear regression analyses were performed to identify predictors of CRF.
ResultsThere was no difference in CRF between adults with a normal weight (BMI between 18.5–24.9 kg/m2) and those who were overweight (BMI 25.0–29.9 kg/m2). Subjects who were underweight (BMI < 18.5 kg/m2) as well as females who were obese (BMI ≥ 30.0 kg/m2) showed a reduced CRF compared to the normal and overweight groups. Age, height, and gender were significant predictors of CRF (R2 = 0.467, P < 0.0001); BMI did not add significantly to this relationship.
ConclusionOur findings indicate that BMI was not associated with CRF in addition to age, height, and gender. In subjects with a BMI < 18.5 kg/m2, CRF was lower compared to subjects with a BMI between 18.5 and 29.9 kg/m2. In obese subjects, CRF was only lower in females compared to females with a BMI between 18.5 and 29.9 kg/m2. Correcting CRF for BMI may be beneficial for subjects with a low BMI, and females with a BMI ≥ 30.0 kg/m2. The outcome of this study might help to improve the interpretation of exercise testing results in individuals with a low or high BMI.