Background: This analysis helps clarify the individual and joint effects of moderate to vigorous physical activity (MVPA) in concert with significant life events (eg, divorce, marriage, job change or loss, pregnancy, etc) on weight following a behavioral weight loss intervention. Methods: Data from the Tracking Study weight loss trial were utilized to perform a 4-way decomposition of moderation and mediation of life events (≥ 1 vs 0) and MVPA (low <2500 kcal vs high ≥ 2500 kcal) on 24-month weight. Results: The total effect of life events and MVPA on weight was estimated to be 1.63 kg (95% confidence interval = 0.30 to 2.96; P = .02). The controlled direct effect of life events on 24-month weight suggested that experiencing at least one life event controlling for MVPA was associated with an increase of 2.31 kg (95% confidence interval = 0.29 to 4.33) at 24 months. Other interaction and mediation estimates were not statistically significant. Conclusions: This analysis offers new potential for examining health behaviors that may act as both mediators and effect modifiers of health. Although more work is needed to understand the interaction of life events and MVPA on weight loss maintenance, findings help rule out mediation. Life events and MVPA should be considered for their unique effects on weight loss maintenance in the future.
Kara L. Gavin, Julian Wolfson, Mark Pereira, Nancy Sherwood and Jennifer A. Linde
Meghan M. Senso, Stewart G. Trost, A. Lauren Crain, Elisabeth M. Seburg, Julie D. Anderson and Nancy E. Sherwood
Although the prevalence of obesity in young children highlights the importance of early interventions to promote physical activity (PA), there are limited data on activity patterns in this age group. The purpose of this study was to describe activity patterns in preschool-aged children and explore differences by weight status.
Analyses use baseline data from Healthy Homes/Healthy Kids–Preschool, a pilot obesity prevention trial of preschool-aged children who are overweight or at risk for being overweight. A modified parent-reported version of the previous-day PA recall was used to summarize types of activity. Accelerometry was used to summarize daily and hourly activity patterns.
“Playing with toys” accounted for the largest proportion of a child’s previous day, followed by “meals and snacks” and “chores.” Accelerometry-measured daily time spent in sedentary behavior, light PA, and moderate-to-vigorous PA (MVPA) was 412, 247, and 69 minutes, respectively. Percentage of hourly time spent in MVPA ranged from 3% to 13%, peaking in the late morning and evening hours. There were no statistically significant MVPA differences by weight status.
This study extends our understanding of activity types, amounts, and patterns in preschool-aged children and warrants further exploration of differences in PA patterns by weight status.
Brian C. Martinson, A. Lauren Crain, Nancy E. Sherwood, Marcia G. Hayes, Nicolaas P. Pronk and Patrick J. O’Connor
To assess the representativeness of older adults recruited to a physical activity maintenance RCT by conducting sequential comparisons to characterize study sample composition changes occurring between sampling frame construction and study enrollment.
Study subjects (N = 1049) were 50 to 70 year old men and women who had increased physical activity within the past year recruited from a Midwestern managed care organization.
Those responding to an initial mailed screener differed on demographic, behavioral, and SES characteristics from those not responding. Compared with ineligibles, eligible individuals were significantly younger, more highly educated, and more likely to report improved health in the prior year. Compared with eligible individuals who did not enroll, enrollees had generally higher education and income.
Physical activity promotion programs in older adults may have limited reach and substantial volunteer bias. Additional strategies to increase the reach of physical activity interventions into the target population are needed.