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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #167391
Title: INFLUENCE OF BODY COMPOSITION ON PHYSICAL ACTIVITY STUDIES USING DOUBLY LABELED WATER

Author
item MASSE, LOUISE - NATL.CANCER INST.
item FULTON, JANET - CENTERS/DISEASE CONTR
item WATSON, KATHLEEN - BAYLOR COLLEGE/MEDICINE
item MAHAR, MATTHEW - EAST CAROLINA UNIVERSITY
item MEYERS, MICHAEL - WEST TEXAS A&M UNIVERSITY
item Wong, William

Submitted to: Journal of Applied Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/4/2003
Publication Date: 12/5/2003
Citation: Masse,L.C., Fulton,J.E., Watson,K.L., Mahar,M.T., Meyers,M.C., Wong,W.W. 2004. Influence of body composition on physical activity validation studies using doubly labeled water. Journal of Applied Physiology. 96:1357-1364.

Interpretive Summary: Physical activity is inversely related to many chronic diseases and plays an important role in preventing and managing obesity, which has reached epidemic levels in the United States. Currently, no universally agreed-on standard exists for validating measures of physical activity. The doubly labeled water (DLW) methodology is believed to be the most accurate method for assessing energy expenditure in free-living conditions including physical activity. We enrolled 136 African-American and Hispanic women in a study to evaluate the effects of body composition on the agreement between physical activity estimated by either accelerometry or activity diary and by the DLW method. Our results showed that accelerometry and activity diary accounted for a small portion of total energy expenditure and physical activity energy expenditure. Most of the variance in the energy expenditure measurements made by the DLW method was explained by body mass or lean tissue mass. Therefore, body mass or lean tissue mass must be taken into account when the DLW method is used as a validation standard to evaluate other physical activity measures.

Technical Abstract: This study investigated the influence of two approaches (mathematical transformation and statistical procedures), used to account for body composition [body mass or fat-free mass (FFM)], on associations between two measures of physical activity and energy expenditure determined by doubly labeled water (DLW). Complete data for these analyses were available for 136 African American (44.1%) and Hispanic (55.9%) women (mean age 50 +/- 7.3 yr). Total energy expenditure (TEE) by DLW was measured over 14 days. Physical activity energy expenditure (PAEE) was computed as 0.90 x TEE - resting metabolic rate. During week 2, participants wore an accelerometer for 7 consecutive days and completed a 7-day diary. Pearson's product-moment correlations and three statistical procedures (multiple regressions, partial correlations, and allometric scaling) were used to assess the effect of body composition on associations. The methods-comparison analysis was used to study the effect of body composition on agreement. The statistical procedures demonstrated that associations improved when body composition was included in the model. The accelerometer explained a small but meaningful portion of the variance in TEE and PAEE after body mass was accounted for. The methods-comparison analysis confirmed that agreement with DLW was affected by the transformation. Agreement between the diary (transformed with body mass) and TEE reflected the association that exists between body mass and TEE. These results suggest that the accelerometer and diary accounted for a small portion of TEE and PAEE. Most of the variance in DLW-measured energy expenditure was explained by body mass or FFM.