Changing the sedentary time and physical activity trajectories of obese adolescents: Results from the CAFAP controlled clinical trial

Abstract

Introduction: Adolescents are typically on trajectories of increasing sedentary timeanddecreasingmoderate/vigorousphysical activity. Overweight and obese adolescents may have poorer activity profiles than normal weight adolescents and therefore be at increased risk of activity-related physical and mental health problems. As activity behaviours tend to track from adolescence to adulthood, altering adolescent activity trajectories is likely to have long-term health consequences. This study aimed to evaluate the immediate and 12 month post-intervention effectiveness of an intervention focused on changing the sedentary and physical activity behaviours of obese adolescents. Methods: Sixty nine adolescents aged 14.1 (SD 1.6) years participated in awithin-subjects staggered-entrywaitlist controlled trial ofCurtinUniversity’sActivity, FoodandAttitudesProgram(CAFAP). CAFAP involved an 8 week intensive multi-disciplinary familybased community intervention with tapered text message and phone support for 12 months. Sedentary time and light, moderate and vigorous activity were measured using Actical accelerometers worn on the hip for a week. Fifty six participants provided adequate accelerometer data in at least two assessments and were included in linear mixed model analysis. Activity profile patterns were assessed with Exposure Variation Analysis. Results: On entry to the study adolescents were sedentary for 70.3% of their awake wear day, with 25.4% spent in light activity, 4.2% in moderate activity and just 0.2% spent in vigorous activity. 28.1% of their wear day was spent in bouts of sedentary time of at least 30min duration, with 9.8% spent in sedentary bouts of 60min ormore. During the control period adolescents showed trajectories of increasing daily sedentary time (mean 532.3 [SE 3.3] to 548.2 [3.7], p=0.003) and decreasing daily light activity (199.7 [2.7] to 186.4 [3.5], p=0.007) with decreasing trends for moderate (31.1 [1.3] to 29.4 [1.1], p=0.147) and vigorous (1.5 [0.2] to 1.3 [0.2], p=0.470) activity. During the intervention period these trajectories were reversedwithmonthly rates of change showing a decrease for sedentary time (−5.1 [95% CI −11.0, 0.8]) and an increase for moderate physical activity (1.8 [−0.04, 3.6]). Sedentary time and light, moderate and vigorous activity levels remained stable over the 12month maintenance period. There were no significant reductions in prolonged bouts of sedentary time following the intervention. Discussion: The CAFAP intervention was effective in changing the sedentary time and physical activity trajectories of obese adolescents suggesting behavior focused interventions have the potential to create long-term health changes. However trajectories of prolonged sedentary time were not changed in the intervention and thus further development of interventions targeting the pattern of sedentary behaviour is required.