Autonomous motivation and action planning are longitudinally associated with physical activity during adolescence and early adulthood

Abstract

We examined the associations of autonomous motivation, controlled motivation, and physical activity (PA) planning with PA participation over six years across the adolescent-to-adult transition. Participants from the NEXT Generation Health Study, a nationally representative cohort study of U.S. 10^th graders (N=2785), completed surveys yearly from 2010 to 2016 (four years post-high school). This study used data from Waves 2 (W2) through 7 (W7). Data were analyzed using growth models accounting for the complex survey design and controlling for sex, race/ethnicity, and body mass index. A piecewise growth model with two pieces (Piece 1: W2-W4; Piece 2: W4-W7) indicated that PA declined during late adolescence (W2-W4) (b=-0.31, β=-0.22, p<.001), but did not decline after the transition into early adulthood (W4-W7) (b=-0.08, β=-0.04, p=.052). Autonomous motivation was positively associated with PA at all waves (b=0.23-0.33, β=1.90-4.37, p<.001). Controlled motivation was only positively associated with PA at W3 (12^th grade) (b=0.13, β=1.54, p=.011). PA planning varied significantly between individuals and significantly predicted PA (b=0.44, β=0.21, p<.001). Although PA decreased significantly during late adolescence, PA did not decrease significantly after transitioning into early adulthood (one to four years post-high school). Elevated autonomous motivation and PA planning were consistently and significantly associated with higher PA, suggesting that these may be useful intervention targets during this adolescent-to-adult transition.

Figure 1. Piecewise Growth Model for Autonomous Motivation, Controlled Motivation and Physical Activity Planning on Longitudinal Participation in Physical Activity

Note. PA represents the outcome, physical activity, at waves 2–7. AUTMOT represents the effects of autonomous motivation for time spent in PA. CONMOT represents the effects of controlled motivation for time spent in PA. PAPLAN represents the effects of physical activity planning. i represents the intercepts at each wave. s1 represents the slope for the first piece of the model (W2–W4), s2 represents the slope for the second piece of the model (W4–W7), and stvc represents the random slope for physical activity planning. BMI=Body mass index.

Figure 2. Effects of Autonomous Motivation, Controlled Motivation, and Physical Activity Planning on Longitudinal Participation in Physical Activity

Note. * Autonomous motivation for time spent in PA was significantly and positively associated with physical activity at all times (b=0.22-0.32, β=1.90-4.37, p<.001). ^§Physical activity planning had a random slope and significantly and positively predicted with physical activity participation (b=0.44, β=0.21, p<.001). ^¥Controlled motivation for time spent in PA was significantly associated with physical activity participation at wave 3 (b=0.13, β=1.54, p=.011), but not at any other time point. £Physical activity without controlling for autonomous motivation, controlled motivation, or physical activity planning. The solid vertical line separates Piece 1 (W2–W4) and Piece 2 (W4–W7) of the piecewise growth model.