Abstract
IntroductionSurveillance of physical activity (PA) is increasingly based on accelerometry. However, data management guidelines are lacking. We propose an approach for combining accelerometry and diary based PA information for assessment of PA in adolescents and provide an example of this approach using data from German adolescents.MethodsThe 15-year-old participants comprised a subsample the GINIplus birth cohort (n = 328, 42.4% male). Data on PA was obtained from hip-worn accelerometers (ActiGraph GT3X) for seven consecutive days, combined with a prospective activity diary. Major aspects of data management were validity of wear time, handling of non-wear time and diary comments. After data cleaning, PA and percentage of adolescents meeting the recommendations for moderate-to-vigorous activity (MVPA) per day were determined.ResultsFrom the 2224 recorded days 493 days (25%) were invalid, mainly due to uncertainties relating to non-wear time (322 days). Ultimately, 269 of 328 subjects (82%) with valid data for at least three weekdays and one weekend day were included in the analysis. Mean MVPA per day was 39.1 minutes (SD ±25.0), with boys being more active than girls (41.8±21.5 minutes vs. 37.1±27.8 minutes, p<0.001). Accordingly, 24.7% of boys and 17.2% of girls (p<0.01) met the WHO recommendations for PA. School sport accounted for only 6% of weekly MVPA. In fact, most MVPA was performed during leisure time, with the majority of adolescents engaging in ball sports (25.4%) and endurance sports (19.7%). Girls also frequently reported dancing and gymnastics (23%).ConclusionFor assessment of PA in adolescents, collecting both accelerometry and diary-based information is recommended. The diary is vital for the identification of invalid data and non-compliant participants. Preliminary results suggest that four out of five German adolescents do not meet WHO recommendations for PA and that school sport contributes only little to MVPA.
Highlights
Surveillance of physical activity (PA) is increasingly based on accelerometry
Data Management and Quality Control A total of 328 participants providing 2,224 recording days were subjected to the quality control criteria as described (Figure 2)
In 50% (199 days) the discrepancy between wear time according to the National Health and Nutrition Examination Survey (NHANES) algorithm [33] and diary data exceeded the accepted criteria of minus 45 minutes and plus 150 minutes per day
Summary
Surveillance of physical activity (PA) is increasingly based on accelerometry. data management guidelines are lacking. Being physically active is considered to have protective effects on adiposity, mental, cardiometabolic as well as musculoskeletal health [1,2]. The interest in individuals at young age is important because acquired behaviour patterns sustain into adulthood [4] Active adolescents have both a higher chance to be active as an adult and to remain healthy until old age. Inactivity has become a major public health concern For this reason, a major goal is to promote PA already during childhood, for both an improved health status and a decrease in social economic cost
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