Document Type


Degree Name



Oregon Health & Science University


frequently use accelerometers to measure physical activity energy expenditure (PAEE) in free-living persons. Although accelerometers are promising tools for this purpose, few studies have validated accelerometry against gold standard methods, such as the doubly labeled water (DLW) method. To address this gap in research, this cross-sectional study compared direct measurement of PAEE with the Actical® Activity Monitor to PAEE calculated from the DLW method. Total energy expenditure was measured over a seven-day period using DLW. PAEE was estimated by subtracting resting energy expenditure and thermic effect of food from total energy expenditure. Simultaneously, PAEE was measured by accelerometry with an Actical® Activity Monitor. PAEE measured by each technique were compared using Student’s paired

t-tests, linear regression models, and the Bland-Altman method.

Sixty-two L-T

4 treated euthyroid women and healthy control women completed all measurements. Compared to the DLW method, the Actical® underestimated PAEE by an average of 193 ± 350 kcal/day. Using linear regression, there was a negative correlation between BMI (p = 0.031) and fat mass (p = 0.048) and the difference in PAEE estimated by the two methods.

In this sample of participants, PAEE estimated by Actical® was lower than PAEE estimated by the DLW method among 74% (n = 46) of participants. The large differences observed between the two measures of PAEE may limit the ability of the Actical® to accurately measure PAEE in free-living conditions. Future research is needed to optimize accelerometer accuracy.




Graduate Programs in Human Nutrition


School of Medicine



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