Sources of variance in daily physical activity levels in the seasonal variation of blood cholesterol study
Authors
Matthews, Charles E.Hebert, James R.
Freedson, Patty S.
Stanek, Edward J.
Merriam, Philip A.
Ebbeling, Cara B.
Ockene, Ira S.
UMass Chan Affiliations
Department of Medicine, Division of Cardiovascular MedicineDepartment of Medicine, Division of Preventive and Behavioral Medicine
Document Type
Journal ArticlePublication Date
2001-06-01Keywords
*Activities of Daily LivingAdult
Aged
Cholesterol
Epidemiologic Studies
Female
Humans
Longitudinal Studies
Male
Middle Aged
Occupations
*Physical Fitness
Recreation
Reproducibility of Results
*Seasons
epidemiologic measurements
exercise
reproducibility of results
seasons
MET(s)
metabolic equivalent(s)
SD
standard deviation
SEASON
Seasonal Variation of Blood Cholesterol
Biochemical Phenomena, Metabolism, and Nutrition
Cardiology
Cardiovascular Diseases
Environmental Public Health
Epidemiology
Lipids
Musculoskeletal, Neural, and Ocular Physiology
Polycyclic Compounds
Metadata
Show full item recordAbstract
The authors examined sources of variance in self-reported physical activity in a cohort of healthy adults (n = 580) from Worcester, Massachusetts (the Seasonal Variation of Blood Cholesterol Study, 1994-1998). Fifteen 24-hour physical activity recalls of total, occupational, and nonoccupational activity (metabolic equivalent-hours/day) were obtained over 12 months. Random effects models were employed to estimate variance components for subject, season, day of the week, and residual error, from which the number of days of assessment required to achieve 80% reliability was estimated. The largest proportional source of variance in total and nonoccupational activity was within-subject variance (50-60% of the total). Differences between subjects accounted for 20-30% of the overall variance in total activity, and seasonal and day-of-the-week effects accounted for 6% and 15%, respectively. For total activity, 7-10 days of assessment in men and 14-21 days of assessment in women were required to achieve 80% reliability. For nonoccupational activity, 21-28 days of assessment were required. This study is among the first to have examined the sources of variance in daily physical activity levels in a large population of adults using 24-hour physical activity recall. These findings provide insight for understanding the strengths and limitations of short term and long term physical activity assessments employed in epidemiologic studies.Source
Am J Epidemiol. 2001 May 15;153(10):987-95.
DOI
10.1093/aje/153.10.987Permanent Link to this Item
http://hdl.handle.net/20.500.14038/26394PubMed ID
11384955Related Resources
ae974a485f413a2113503eed53cd6c53
10.1093/aje/153.10.987
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