Background: Previous studies based on self-reports show that a majority of children and adolescents in Western countries fail to achieve the recommendation of 60 minutes moderate to vigorous physical activity (PA) on a daily basis. The specific aim of the study was to analyze the relationship between directly measured and self-reported PA in a cross-sectional sample of Finnish secondary school students. More-over, how large proportion of adolescents accumulate at least 60 minutes of moderate to vigorous PA on a daily basis using self-reports and direct measure scores.

Methods: Participants were recruited from a secondary school located in Northeast Finland. The sample comprised 96 students (58 girls, 38 boys) aged between 12- to 16-years (M = 15.03, SD = .94). Students’ directly measured PA was collected using accelerometers over a seven-day period. The self-reported PA data was gathered during the school’s allotted 90-minute lessons.

Results: Results indicated that girls and boys were similarly physically active, based PA measured using both accelerometers and questionnaires. Grade 7 students were physically more active than Grade 9 students when PA was assessed using self-reports but no significant difference was found when direct measure scores were used. Self-reported PA emerged as the significant positive predictor for students’ directly measured PA within Grade 8 (p < .001), and Grade 9 students (p < .01). The results highlighted that only 10% of adolescents met the recommendation of 60 minutes moderate to vigorous PA daily, when PA was measured using self-reports. On the contrary, a portion of 85% of students met the recommendation, when direct measure scores were used.

Conclusion: Because the current and previous findings indicated substantial differences in the assessments results for similarly aged samples, continuing studies using directly assessed techniques are required to gain detailed information concerning the PA behavior of Finnish children and adolescents.