Accelerometer Measured Physical Activity and Obesity

The use of accelerometers to objectively measure physical activity (PA) volume does not account for inter-individual differences in body mass or cardiorespiratory fitness among adults, which may contribute to the commonly observed discrepancies between objective and subjective measures of PA. Using a sample of 6149 adults from the National Health and Nutrition Survey, the first study demonstrated that for given accelerometer count, individuals with overweight and obesity had a greater rate of energy expenditure than normal weight, and that accounting for differences in energy expenditure due to body mass reduced discrepancies between objective and subjective measures of PA. The second study demonstrated that current accelerometer threshold values used to measure durations of PA may not correspond to the appropriate respective relative intensity of PA after accounting for maximal oxygen consumption by sex and body mass index categories in 828 adults. These results suggest that the established accelerometer thresholds may bias measures of objective PA for individuals with obesity and this may contribute to the discrepancies seen between objective and subjective measures of PA volume.