U.S. Cohort Differences in Body Composition Outcomes of a 6-Month Pedometer-Based Physical Activity Intervention: The ASUKI Step Study

BACKGROUND: Regular physical activity (PA) enhances health and is an important factor in disease prevention and longevity. The 2008 U.S. Physical Activity Guidelines recommends that all healthy adults attain at least 150 minutes per week of moderate intensity aerobic PA (e.g., brisk walking) to maintain and promote PA. OBJECTIVES: This study determined the effects of a 6-month pedometer-based worksite walking intervention with participants focusing on a goal of achieving 10,000 steps per day, on body composition in adults with a wide range of body mass index (BMI) values and compares the changes with outcomes of similar studies. MATERIALS AND METHODS: The design was a single group, quasi-experimental study. All participants received a pedometer and were asked to register the daily number of steps. Men and women (n = 142; age = 41 ± 11.5 years; BMI = 27.2 ± 7.25 kg.m(-2)) received body composition measures at 1, 3, and 6 months. A multilevel growth modeling approach was used to explore change over time and to predict change by steps, age, gender, and fat category categorized as normal and overweight/obese. RESULTS: Significant individual differences in linear slopes and change over time were observed for waist circumference (WC) (-3.0 cm) only in unconditional model (t = -0.67, P = 0.02). CONCLUSIONS: A 3.0 cm loss in WC shows that a 10,000 step per day walking program has the potential to influence changes in body composition measures that are correlated with adverse health outcomes. While significant changes did occur there are some limitations. The analysis did not consider the data regarding completing of 10,000 steps per day and other potential factors that could influence the results. Compliance to the walking dose and initial physical activity and body composition levels are important to consider when studying body composition changes in such programs.