Validation of a 7-day physical activity diary against doubly-labelled water

Background: The assessment of physical activity intensity and duration is essential for understanding group activity patterns. Methods: The present study evaluated the validity of measurement of total energy expenditure (TEE) and physical activity level (PAL) using a categorized physical activity diary. In 29 young healthy men, aged 18-27 years, with body mass index range 21-43 kg m(-2), TEE using doubly-labelled water (DLW), resting metabolic rate (RMR) by indirect calorimetry, physical activity level (PAL defined as TEE/RMR) and activity pattern, timing and level from 7-day physical activity diaries were determined. Results: TEE by DLW and estimated by activity diary were correlated (r = 0.61, p = 0.005). The mean underestimation of TEE by the activity diary compared with the DLW method was 2.50 0.72 MJ day(-1). Sedentary (lying, sitting and standing) time averaged 18 h day-1 and was negatively correlated with PAL (r = -0.44, p = 0.018) whilst time spent in light intensity activity (5 h day(-1)) was positively correlated (r = 0.51, p = 0.005). Conclusions: It is concluded that the categorized physical activity diary measured TEE with limited accuracy but presents an inexpensive, convenient method of discriminating individual and group physical activity patterns.