Cardiorespiratory Fitness of Otherwise Healthy Obese Women

PURPOSE: Cardiorespiratory fitness (CRF) is used as a diagnostic and prognostic health indicator for all-cause and cardiovascular disease mortality (Lee et al, 2010). Thus, properly quantifying and interpreting CRF is important for accurate diagnoses. The current EACPR/AHA Scientific Statement includes peak oxygen uptake (VO2peak) both in ml/min/kg and as percent of predicted (Guazzi et al, 2016).We have previously shown, in a small cohort of otherwise healthy obese women (n = 26), that obese adults have normal or slightly reduced CRF (~85% of predicted), depending on the prediction equation used (Lorenzo & Babb, 2012). Here, we wanted to validate our earlier findings in a larger sample of women. METHODS: Obese women underwent hydrostatic weighing to assess body fat percentage, fat mass, and lean body mass. They then completed an incremental cycling test to exhaustion to determine VO2peak. Prediction equations from Riddle et al (R; 1980), Wasserman et al (W; 2005), and Gläser (G; 2010) were used to assess CRF as previously described. Differences between percent predicted VO2peak values derived from the three equations were analyzed using repeated measures ANOVA. RESULTS: Data from 121 women (34 ± 7 yr, 36 ± 4 kg/m2 BMI, 46 ± 5% body fat, 44 ± 9 kg fat mass, 52 ± 6 kg lean body mass, mean ± SD) were analyzed. VO peak (ml/min/kg) was low (18.9 ± 3.0 ml/min/kg) and decreased with increasing body mass, severely penalizing heavier individuals. In fact, applying the current ACSM CRF classification, 113 women would be considered “very poor” and 8 as “poor” (all below the 25th percentile). Mean values of % predicted VO peak were significantly different between equations R and W, and W and G, but not between R and G (R: 92 ± 14%, W: 91 ± 14%, G: 92 ± 14%, p < 0.01). Using a cutoff for low CRF of < 84% of predicted VO2peak, only 27-32% of women fell into this category, depending on the equation used. CONCLUSIONS: The commonly used method of evaluating VO2peak based on body weight (ml/kg/min) is not appropriate in obese individuals; VO2peak as percent of predicted is a better alternative when assessing CRF. Similar to our previous data in a small cohort of otherwise healthy obese women, the current data show that the majority of obese women have normal CRF, independent of the prediction equation used.