title: Age-related patterns of vigorous-intensity physical activity in youth: The International Children's Accelerometry Database.
abstract: Physical activity declines during youth but most evidence reports on combined moderate and vigorous-intensity physical activity. We investigated how vigorous-intensity activity varies with age. Cross-sectional data from 24,025 participants (5.0-18.0 y; from 20 studies in 10 countries obtained 2008-2010) providing ≥ 1 day accelerometer data (International Children's Accelerometry Database (ICAD)). Linear regression was used to investigate age-related patterns in vigorous-intensity activity; models included age (exposure), adjustments for monitor wear-time and study. Moderate-intensity activity was examined for comparison. Interactions were used to investigate whether the age/vigorous-activity association differed by sex, weight status, ethnicity, maternal education and region. A 6.9% (95% CI 6.2, 7.5) relative reduction in mean vigorous-intensity activity with every year of age was observed; for moderate activity the relative reduction was 6.0% (5.6%, 6.4%). The age-related decrease in vigorous-intensity activity remained after adjustment for moderate activity. A larger age-related decrease in vigorous activity was observed for girls (- 10.7%) versus boys (- 2.9%), non-white (- 12.9% to - 9.4%) versus white individuals (- 6.1%), lowest maternal education (high school (- 2.0%)) versus college/university (ns) and for overweight/obese (- 6.1%) versus healthy-weight participants (- 8.1%). In addition to larger annual decreases in vigorous-intensity activity, overweight/obese individuals, girls and North Americans had comparatively lower average vigorous-intensity activity at 5.0-5.9 y. Age-related declines in vigorous-intensity activity during youth appear relatively greater than those of moderate activity. However, due to a higher baseline, absolute moderate-intensity activity decreases more than vigorous. Overweight/obese individuals, girls, and North Americans appear especially in need of vigorous-intensity activity promotion due to low levels at 5.0-5.9 y and larger negative annual differences.
authors.affiliation: MRC Epidemiology Unit and UKCRC Centre for Diet and Activity Research (CEDAR), University of Cambridge School of Clinical Medicine, Box 285, Institute of Metabolic Science, Cambridge Biomedical Campus, Cambridge CB2 0QQ, United Kingdom.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Corder
authors.affiliation: MRC Epidemiology Unit and UKCRC Centre for Diet and Activity Research (CEDAR), University of Cambridge School of Clinical Medicine, Box 285, Institute of Metabolic Science, Cambridge Biomedical Campus, Cambridge CB2 0QQ, United Kingdom.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Sharp
authors.affiliation: MRC Epidemiology Unit and UKCRC Centre for Diet and Activity Research (CEDAR), University of Cambridge School of Clinical Medicine, Box 285, Institute of Metabolic Science, Cambridge Biomedical Campus, Cambridge CB2 0QQ, United Kingdom.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Atkin
authors.affiliation: Department of Sport Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark; Norwegian School of Sport Science, Oslo, Norway.
authors.forename: Lars B
authors.initials: LB
authors.lastname: Andersen
authors.affiliation: Department of Movement and Sports Sciences, Ghent University, Ghent, Belgium.
authors.forename: Greet
authors.initials: G
authors.lastname: Cardon
authors.affiliation: Centre for Exercise, Nutrition and Health Sciences, University of Bristol, Bristol, UK.
authors.forename: Angie
authors.initials: A
authors.lastname: Page
authors.affiliation: Centre for Research and Action in Public Health, University of Canberra, Canberra, Australia.
authors.forename: Rachel
authors.initials: R
authors.lastname: Davey
authors.affiliation: Department of Sport Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Grøntved
authors.affiliation: Federal University of Pelotas, Pelotas, Brazil.
authors.forename: Pedro C
authors.initials: PC
authors.lastname: Hallal
authors.affiliation: Department of Health and Human Physiology, University of Iowa, Iowa City, US.
authors.forename: Kathleen F
authors.initials: KF
authors.lastname: Janz
authors.affiliation: School of Social and Community Medicine, University of Bristol, UK.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kordas
authors.affiliation: Epidemiology, Biostatistics and Public Health Institute, University of Zürich, Switzerland.
authors.forename: Susi
authors.initials: S
authors.lastname: Kriemler
authors.affiliation: Service of Endocrinology, Diabetes and Metabolism, Centre Hospitalier Universitaire Vaudois, University of Lausanne, Switzerland; Division of Pediatric Endocrinology, Diabetology and Obesity, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland.
authors.forename: Jardena J
authors.initials: JJ
authors.lastname: Puder
authors.affiliation: Exercise and Health Laboratory, Faculty of Human Movement, Technical University of Lisbon, Lisbon, Portugal.
authors.forename: Luis B
authors.initials: LB
authors.lastname: Sardinha
authors.affiliation: MRC Epidemiology Unit and UKCRC Centre for Diet and Activity Research (CEDAR), University of Cambridge School of Clinical Medicine, Box 285, Institute of Metabolic Science, Cambridge Biomedical Campus, Cambridge CB2 0QQ, United Kingdom; Norwegian School of Sport Science, Oslo, Norway.
authors.forename: Ulf
authors.initials: U
authors.lastname: Ekelund
authors.affiliation: MRC Epidemiology Unit and UKCRC Centre for Diet and Activity Research (CEDAR), University of Cambridge School of Clinical Medicine, Box 285, Institute of Metabolic Science, Cambridge Biomedical Campus, Cambridge CB2 0QQ, United Kingdom.
authors.forename: Esther M F
authors.initials: EM
authors.lastname: van Sluijs
keywords: Adolescent; Child; Epidemiology; ICAD; Motor activity