The purpose of this study is to evaluate whether the use of an activity monitor providing feedback has an effect on physical activity (PA) in young men. A population-based sample of 276 conscription-aged (mean = 17.9, SD = 0.7 years) men participated in a 3-month randomized controlled trial in Oulu in 2012. Participants were randomized to an intervention group (INT, N = 137) and a control group (CON, N = 139). INT received a wrist-worn monitor (Polar Active) showing daily activity, and CON received identical monitors without feedback. Main outcome was the change from baseline in objectively measured weekly time spent in moderate-to-vigorous PA (MVPA) and sedentary activity (SED), as assessed by generalized estimation equations (GEE). Other lifestyle factors were assessed by a questionnaire at baseline and at 3 months. Weekly physical activity data (≥ 4 days with ≥ 8 h each) were obtained from 72 (53%) and 90 (65%) men in the INT and CON, respectively. Based on GEE, time spent in MVPA increased (p = 0.012) and SED decreased (p = 0.032) in the INT compared with the CON. During the first 7 weeks, the INT spent on average 1 h less sedentary than the CON (t-test, p < 0.05). During the first week, the INT showed 12 minutes more MVPA compared to the CON (t-test, p = 0.034). Based on questionnaire data, the proportion of the most sedentary men decreased in the INT (Wilcoxon test, 28% vs. 10%, p = 0.029), with no change in the CON (20% vs. 19%, p = 0.546). To conclude, a wrist-worn activity monitor providing feedback had a short-term positive effect on PA and SED in young men.Trial registrationThis is a pilot study for a larger randomized controlled trial registered to the clinical trials register NCT01376986.

BackgroundSedentary behavior is associated with poor well-being in youth with adverse trajectories spanning to adulthood. Still, its determinants are poorly known. Our aim was to profile sedentary and non-sedentary young men and to clarify their differences in a population-based setting.MethodsA total of 616 men (mean age 17.9, SD 0.6) attending compulsory conscription for military service completed a questionnaire on health, health behavior, socioeconomic situation and media use. They underwent a physical (body composition, muscle and aerobic fitness) and medical examination. Profiles were formed by principal component analysis (PCA).ResultsA total of 30.1 % men were sedentary (daily leisure-time sitting ≥5 h) and 28.9 % non-sedentary (sitting ≤2 h). The sedentary men had more body fat, more depressive symptoms, but lower fitness and life satisfaction than non-sedentary men. However, according to PCA, profiles of unhealthy eating, life-dissatisfaction, and gaming were detected both among sedentary and non-sedentary men, as well as high self-rated PA and motives to exercise.ConclusionDeterminants of sedentary and non-sedentary lifestyles were multiple and partially overlapping. Recognizing individual patterns and underlying factors of the sedentary lifestyle is essential for tailored health promotion and interventions.