Research article summary (published 5 Jul 2009):

Isotemporal substitution paradigm for physical activity epidemiology and weight change.

Full Abstract

For a fixed amount of time engaged in physical activity, activity choice may affect body weight differently depending partly on other activities' displacement. Typical models used to evaluate effects of physical activity on body weight do not directly address these substitutions. An isotemporal substitution paradigm was developed as a new analytic model to study the time-substitution effects of one activity for another. In 1991-1997, the authors longitudinally examined the associations of discretionary physical activities, with varying activity displacements, with 6-year weight loss maintenance among 4,558 healthy, premenopausal US women who had previously lost >5% of their weight. Results of isotemporal substitution models indicated widely heterogeneous relations with each physical activity type (P < 0.001) depending on the displaced activities. Notably, whereas 30 minutes/day of brisk walking substituted for 30 minutes/day of jogging/running was associated with weight increase (1.57 kg, 95% confidence interval: 0.33, 2.82), brisk walking was associated with lower weight when substituted for slow walking (-1.14 kg, 95% confidence interval: -1.75, -0.53) and with even lower weight when substituted for TV watching. Similar heterogeneous relations with weight change were found for each activity type (TV watching, slow walking, brisk walking, jogging/running) when displaced by other activities across these various models. The isotemporal substitution paradigm may offer new insights for future public health recommendations.

Author information

Author/s: Mekary, Rania A (RA); Willett, Walter C (WC); Hu, Frank B (FB); Ding, Eric L (EL);

Affiliation: Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts 02115-1204, USA. rmekary(-atsign-)hsph.harvard.edu

Grants: R25 CA098566 (Agency:NCI NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Journal: American journal of epidemiology (Am J Epidemiol), published in United States. (Language: eng)

Reference: 2009-Aug; vol 170 (issue 4) : pp 519-27

Dates: Created 2009/07/29; Completed 2009/08/11; Revised 2009/08/31;

PMID: 19584129, status: MEDLINE (last retrieval date: 9/1/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adult Anthropometry - methods Exercise - physiology Female Humans Jogging - physiology Models, Statistical

Prospective Studies Television Time Factors United States Walking - physiology Weight Gain Weight Loss

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