Oxygen Consumption at 30 W of Exercise Is Surrogate for Peak Oxygen Consumption in Evaluation of Cardiorespiratory Fitness in Young-Adult African-American Females

Body mass index (BMI) is negatively correlated with cardiorespiratory fitness, measured by maximal or peak oxygen consumption (VO2peak). VO2peak measurements require heavy aerobic exercise to near exhaustion which increases the potential for adverse cardiovascular events. This study tests the hypothesis that VO2 measured at a fixed submaximal workload of 30 W is a surrogate for VO2peak. We studied 42 normotensive African-American female university students, 18-25 years of age. We measured VO2peak, blood pressure, and VO2 at a 30 W exercise workload and computed BMI. We found significant negative correlations between BMI and VO2peak (r = -0.41, P < 0.01) and between BMI and VO2 at 30 W (r = -0.53, P < 0.001). Compared to VO2peak, VO2 at 30 W increased the significance of the negative correlation with BMI. The heart rate-systolic pressure product at 30 W was positively correlated with BMI (r = 0.36, P < 0.01) and negatively correlated with VO2peak (r = -0.38, P < 0.001). The positive correlation between BMI and the heart rate-systolic pressure product and the greater negative correlation between VO2 and BMI at 30 W of exercise than that at exercise to fatigue suggest that normalized measurements of VO2 at the fixed exercise workload of 30 W could be useful surrogates for measurements of VO2peak.