Research Study Abstract

Objectively Measured Intensity of Physical Activity and Adiposity in Middle-Aged Women

  • Published on 2003

Objective The aim of this study was to evaluate the relationship between objectively measured physical activity (ACT), particularly intensity of physical activity (iACT), and body fat percentage (BF%) in 278 middle-aged women. Secondary purposes were to ascertain the association between physical activity duration (dACT) and BF% and the content to which potentially confounding factors, including total ACT, energy intake, body weight, and season of assessment, influenced the relationship between iACT and BF%.

Research Methods and Procedures A cross-sectional design was used. Subjects were apparently healthy, 35 to 45 years old, premenopausal, nonsmokers, with BMIs <30 kg/m2. Approximately 90 percent were white, 81% were married, and 37% were college graduates. ACT was assessed using Computer Science and Application accelerometers worn for 7 consecutive days. The accelerometers recorded movement continuously, and activity counts were collapsed into 10-minute epochs. Intensity was indexed using seven activity count cut-off points, and duration was based on the number of 10-minute epochs at each intensity level. BF% was assessed using multiple measurements in the Bod Pod. Energy intake was measured using 7-day weighed diet records during the same week subjects wore the accelerometers.

Results BF% was strongly and inversely associated with jACT and dACT. Controlling for energy intake and body weight strengthened the relationships among jACT, dAd, and BF%. Control of total ACT weakened the association.

Discussion Engaging in higher intensity and/or longer duration ACT is associated with lower BF% compared with lower intensity and/or shorter durations of activity.

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Obesity Research