Examining the Influence of Promoting Physical Activity Bouts on Adolescent Movement Dispersion: Secondary Analysis of a Randomized Control Trial

PURPOSE: Most adolescents fail to meet the guidelines for 60 min daily of moderate to vigorous physical activity (MVPA). Movement dispersion provides an alternative approach to evaluating daily physical activity (PA) and sedentary behavior (SB) patterns. Total movement dispersion calculates the spread of PA across the day, considering intensity, while pure movement dispersion calculates the spread as general movement regardless of intensity. Promoting bouts of PA across the day provides a way to infuse movement and create breaks in prolonged SB. Motivational interviewing is a behavioral counseling technique that focuses on motivation for healthy behavior changes. This study examined the influence of motivational interviewing on changes in pure and total movement dispersion among adolescents. DESIGN AND METHODS: This study conducted a secondary analysis of prior research employing motivational interviewing to increase bouts of MVPA and reduce prolonged SB (> 60 min). Participants wore an Actigraph GT3X+ accelerometer on their dominant wrist for 7 days to measure PA and SB pre- and post-intervention. Movement dispersion was calculated from the raw output. RESULTS: A total of 19 participants were included: 14-17 years old, 65% female, and 70% white. The treatment group did not show a significant change in either pure (p = 0.721) or total movement dispersion (p = 0.898) but demonstrated a moderate effect size related to the attention control group (d = 0.708-0.723). PRACTICE IMPLICATIONS: Nurses can encourage adolescents to disperse PA throughout the day to positively impact movement behaviors and reduce prolonged SB. Future research should examine the relationships between movement dispersion and health outcomes, including sleep, quality of life, and non-communicable diseases.