Comparing physical activity assessment methods in the seasonal variation of blood cholesterol study

Purpose: This paper evaluated three measures of physical activity employed in the Seasonal Variation of Blood Cholesterol Study (Seasons), and it had two objectives: 1) To examine the laboratory validity of the Actillume acti vity monitor, and 2) To examine the relative validity of three 24-h physica l activity recalls (24HR) in quantifying short-term physical activity behav iors. Methods: Nineteen healthy middle-age adults completed seven activity trials treading, typing, box moving, stepping, and walking (3.5, 4.25, 5.0 km.h(-1))) while oxygen consumption and Actillume measures were obtained. A NOVA, linear regression, and a scatter plot were employed to examine the va lidity of the Actillume. In relative validity analyses of the 24HR in the S easons study, participants (N = 481) completed two or three 24HR (MET-h.d(- 1)) and a modified Baecke Questionnaire. A subset of the cohort (N = 41) wo re the Actillume for 3-8 d (counts min(-1).d(-1)). The relative validity of the 24HR method was examined by comparison to these criterion measures. Re sults: In laboratory validation analyses, the monitor was found to discrimi nate between sedentary and moderate intensity activities, changes in walkin g speed, and to account for 79% of the variance in oxygen consumption acros s sedentary and walking trials. In relative validity analyses, correlations between the 24HR and the modified Baecke ranged from 0.29 to 0.52 (P < 0.0 1) across total, household, occupational, and leisure-time activities. Conc lusions: In laboratory testing, the Actillume monitor discriminated between sedentary and moderate intensity activities and was highly correlated with oxygen consumption. Three 24HR of physical activity were observed to have a relative validity that was comparable to published data from other short- term activity assessments that also employed the Baecke Questionnaire and a ctivity monitors as criterion measures.