Travis R. Peterson

Improving Exercise Behavior: An Application of the Stages of Change Model in a Worksite Setting:

Randomized trial of 527 corporate employees was conducted to evaluate an exercise intervention based on the transtheoretical model and tailored to individual stages of change. No significant difference in physical activity by stage was evident at baseline among three treatment groups. At follow-up, the group receiving a staged-based message increased activity by 13% and a significant difference was evident in the magnitude and direction of movement across stages, suggesting that tailored messages to stages of change may be an effective strategy for physical activity interventions.

A Prospective Study of Physical Activity Intensity and Change in Adiposity in Middle-Aged Women

Purpose. To determine the extent to which objectively measured intensity of physical activity (PA) predicts change in body fat (BF%) in women. Design. Prospective cohort study of PA intensity and body composition in middle-aged women. Setting. The study took place in a metropolitan Mountain West community. Subjects. Two hundred and twenty-eight women participated in two assessment periods separated by 20 months. Measures. Each assessment period consisted of seven consecutive days of monitoring, followed by body composition testing. Analysis. The general linear model using partial correlations and Mantel-Haenszel χ2 tests were performed. Results. At baseline and follow-up, women who participated in vigorous PA were leaner than women who participated in moderate or light PA (p < .05). Longitudinal results indicated that a greater proportion of women who decreased PA intensity over the 20 months also increased BF% (66%), compared to participants who increased or maintained PA intensity (47%) (p < .05). Conclusions. PA intensity seems to play a role in long-term weight maintenance. Reducing PA intensity increases the risk of BF% gain in women. Efforts to help women maintain PA intensity along with other weight management strategies may prove beneficial in preventing unwanted body fat gain in middle-aged women.

Physical Activity and Body Composition: A 20-Month Prospective Study of Middle-Age Women

Objective: To determine the extent that physical activity accounts for changes in body composition and body weight over time, independent of dietary intake and other potential confounding factors. Methods and Procedures: A cohort of 256 women ages 35-45 at baseline participated in the study. A prospective design was utilized with baseline and follow up assessments 20-months apart. Primary assessments included body weight, body fat percentage, physical activity assessed by accelerometery, and 7-day weighed diet record. Regression analysis was used to determine the extent to which changes in physical activity contributed to changes in body fat percentage and body weight over the study period. Relative risk for change in body fat and weight was calculated using Poisson regression. Results: Over the study period, there were significant changes in body fat percentage, body weight and physical activity. Change in physical activity was a significant predictor of changes in body fat and body weight over the 20-month study period. The impact of change in physical activity on body weight remained significant after controlling for dietary intake and other potential confounding variables. Those in the lower levels of physical activity also had an increased risk of both weight and fat gain over the study period. Discussion: Based on these results, change in physical activity status is an independent predictor of body fat and body weight change over time. Those who are less active also have increased risk of weight and fat gain over time independent of dietary factors.