Compendium Of Physical Activities Underestimates Individual Energy Expenditure Of Healthy Participants

Abstract

PURPOSE: This study evaluated the MET values presented in the CPA for estimating energy expenditure and intensity during laboratory physical activities in a group of fit subjects. METHODS: 10 Subjects, 5 women and 5 men, performed 12 exercise bouts in the laboratory. Activities, including walking and jogging, cycling, and resting assessments, were measured at steady state values. Calisthenics included a specific number of repetitions, but did not reach steady state. Oxygen uptake was measured through indirect calorimetry. RESULTS: Subjects (N=10) represented healthy adults of different ages (28-64 years). The population was in good health, with the average age of 39 years, an average BMI of 24 kg/m2, and an average resting metabolic rate of 3.6 ml/kg/min. The resting metabolic measurements were significantly (P<.000) higher than the CPA prediction of 1.0 MET. Sitting, walking (3.0 mph), jogging (5.0 mph), and cycling (100 watts) had higher measured MET values (P<.000) than CPA. Graded walking measurements matched the CPA "3.5 mph walking uphill" at 3.0 mph and 6% grade, but were much higher at 3.0 mph and 9% grade. Three cycling stages were all higher (P<.000) than similar CPA values (8.7 METs vs 5.5 METs at 100W). For the entire time of steady-state exercise, there was a significantly (p=.015) higher energy expenditure for the group than what was predicted by the CPA (31 kcals in 26 min), but there was a very strong correlation of.959 (P=.000) between the measured and CPA predicted values. CONCLUSIONS: The difference in predicted and measured MET values could be due to individual differences in resting metabolic rate, body composition, and age. Higher METs measured during cycling stages could imply a misclassification of the intensity when using the CPA as a reference. Good correlation between the VO2 measurements and the prediction suggest that using the CPA values could be more accurate in this fit sample if they were corrected for variation in resting metabolic rate. Perhaps the proposed updates to the CPA for specific sub-groups will increase the usability of the CPA for calculating individual energy expenditure.