Self-reported and objective physical activity measurement by active youth

International audienceHealth-related physical activity recommendations are now widely known. To achieve benefits for their health, youth have to accumulate at least 60 minutes of moderate to vigorous intensity activity per day. The accuracy of field measure of physical activity is a complex question and no Gold standard exist. This study compares the data of two accelerometers (Actigraph, GT3X®; Bodymedia, SP3 Armband®), two diaries (assessing respectively self-reported activity and self-reported intensity) and a recall questionnaire. Furthermore, a focus on participants' comfort during data collection was carried out to help to decrease the high dropout rates in these studies. Eighteen young people with a mean age of 11.9 years (SD = 1.97) practicing 3.54 (SD = 2.19) hours of sport per week have worn the two accelerometers, filled self-reported measures in during 7 days. Results showed moderate to high correlations between accelerometer data with nevertheless some difference in time spent to light, moderate or vigorous physical activity (PA). Given (1) that self-reported data were systematically closer to those of the GT3X than those of the SP3 and (2) that GT3X was more appreciated by the participants in terms of wearing comfort and aesthetic, we recommend the use of the GT3X. On the whole data extracted from the self-reported intensity, diary were more correlated with accelerometer data than those of the self-reported activities diary. Such easy to use tool should be preferred to assess PA of physically active young people. Finally, the recall questionnaire does not have proved to be a valid tool