What is ICAD?

Objective methods, such as accelerometers, have become a preferred option when measuring population levels of physical activity, examining trends in activity patterns and when examining associations between activity and health outcomes in young people.

The International Children’s Accelerometry Database (ICAD) project is a consortium including 20 partners which pooled and reduced raw accelerometer data using standardized methods. Data were processed to create comparable accelerometer variables in over 37,000 young people aged 3 to 18 years across studies from Europe, the US, Brazil and Australia. In addition, non-accelerometer data were harmonised in a transparent and structured way.

By pooling data from different studies the ICAD has the potential to:

• increase statistical power due to a large sample size
• create a more heterogeneous and potentially more representative sample
• standardize and optimize the analytical methods used in the generation of outcome variables, and
• provide a means to study the causes of inter-study variability in physical activity.

ICAD2 released

Early 2017, a new version of ICAD was released. Compared to the first release, the updated ICAD includes more longitudinal data and provides access to a wider range of non-accelerometer data. All accelerometer data has been reprocessed to ensure consistency  across waves. Example harmonised variables have been derived for a range of demographic and health-related constructs; further data is available for harmonisation by individual researchers (see Data Harmonisation page).

ICAD funding and management

The initial ICAD project was funded by the National Prevention Research Initiative. ICAD is led by a Steering Committee including representatives from all contributing partners.

The ICAD is managed in collaboration by the MRC Epidemiology Unit, Loughborough University, Norwegian School of Sport Sciences, University of Agder (Norway), and University of East Anglia. A Working Group manages the day-to-day running of ICAD. The ICAD Working Group consists of: Dr Andrew Atkin, Prof Ulf Ekelund, Dr Dale Esliger, Dr Bjorge H Hansen, Dr Lauren Sherar, and Dr Esther van Sluijs.

The database is managed by the MRC Epidemiology Unit and is publicly available for data requests from bona fide researchers across the world. For the purposes of ICAD data sharing the following definition of a bona fide researcher has been adopted (see p24).

Applying to use ICAD data

The ICAD is open for data requests as a supported access resource. Please find information regarding the application process to access the data below. General and pre-submission enquiries should be directed to Lauren Sherar (l.b.sherar@lboro.ac.uk). Please review the available variables, and the information provided on data harmonisation. Please contact datasharing@mrc-epid.cam.ac.uk with data requests using the application form below. Data will be released in chronological order by date of proposal acceptance and is usually within 5 to 10 working days.

• General instructions for ICAD use
• ICAD online Data Dictionary
• ICAD application form
• Data use agreement
• MRC Epidemiology Unit data sharing pages.

Publishing and presenting ICAD Data

• Publication guidelines
• Checklist for publication
• Acknowledgement slide for presentations (with new logo)

Additional material

• ICAD approved proposals and progress (updated Oct 2023)
• List of ICAD partners
• Log of changes to ICAD database
  • Dec 2018: Day-time only summary variables (Evenson cut-points) now available.
• Video of ICAD symposium at ISBNPA Annual Meeting (June 2015, Edinburgh)
• Accelerometry data reduction settings for ICAD 2 (Dec 2015):
  • Summary document
  • Detailed document
• Creating day-time summary variables using hourly data
  • Summary document
  • Stata do file

ICAD publications (most recent first)

ICAD publications on the MRC Epidemiology Unit publications database.

• Kretschmer L, Salali GD, Andersen LB, Hallal PC, Northstone K, Sardinha LB, Dyble M, Bann D; International Children’s Accelerometry Database (ICAD) Collaborators. Gender differences in the distribution of children’s physical activity: evidence from nine countries. Int J Behav Nutr Phys Act (2023)
• Ikeda E, Guagliano JM, Atkin AJ, Sherar LB, Ekelund U, Hansen B, Northstone K, van Sluijs E; International Children’s Accelerometry Database (ICAD) Collaborators. Cross-sectional and longitudinal associations of active travel, organised sport and physical education with accelerometer-assessed moderate-to-vigorous physical activity in young people: the International Children’s Accelerometry Database. Int J Behav Nutr Phys Act (2022)
• Gammon C, Atkin AJ, Corder K, Ekelund U, Hansen BH, Sherar LB, Andersen LB, Anderssen S, Davey R, Hallal PC, Jago R, Kriemler S, Kristensen PL, Kwon S, Northstone K, Pate R, Salmon JO, Sardinha LB, VAN Sluijs EMF; International Children’s Accelerometry Database (ICAD) Collaborators. Influence of Guideline Operationalization on Youth Activity Prevalence in the International Children’s Accelerometry Database. Med Sci Sports Exerc (2022)
• Werneck AO, Jago R, Kriemler S, Andersen LB, Wedderkopp N, Northstone K, Salmon J, van Sluijs EMF; International Children’s Accelerometry Database (ICAD) Collaborators. Association of change in the school travel mode with changes in different physical activity intensities and sedentary time: A International Children’s Accelerometry Database Study. Prev Med (2021)
• Collings PJ, Grøntved A, Jago R, Kriemler S, Northstone K, Puder JJ, Salmon J, Sardinha LB, Steene-Johannessen J, van Sluijs EMF, Sherar LB, Esliger DW, Ekelund U; International Children’s Accelerometry Database (ICAD) Collaborators. Cross-sectional and prospective associations of sleep duration and bedtimes with adiposity and obesity risk in 15 810 youth from 11 international cohorts. Pediatr Obes (2021)
• Brazendale K, Beets MW, Armstrong B, Weaver RG, Hunt ET, Pate RR, Brusseau TA, Bohnert AM, Olds T, Tassitano RM, Tenorio MCM, Garcia J, Andersen LB, Davey R, Hallal PC, Jago R, Kolle E, Kriemler S, Kristensen PL, Kwon S, Puder JJ, Salmon J, Sardinha LB, van Sluijs EMF; International Children’s Accelerometry Database (ICAD) Collaborators. Children’s moderate-to-vigorous physical activity on weekdays versus weekend days: a multi-country analysis. Int J Behav Nutr Phys Act. (2020)
• Aadland E, Kvalheim OM, Hansen BH, Kriemler S, Ried-Larsen M, Wedderkopp N, Sardinha LB, Møller NC, Hallal PC, Anderssen SA, Northstone K, Andersen LB; International Children’s Accelerometry Database (ICAD) Collaborators. The multivariate physical activity signature associated with metabolic health in children and youth: An International Children’s Accelerometry Database (ICAD) analysis. Prev Med (2020).
• Júdice PB, Hetherington-Rauth M, Northstone K, Andersen LB, Wedderkopp N, Ekelund U, Sardinha LB; International Children’s Accelerometry Database (ICAD) Collaborators. Changes in Physical Activity and Sedentary Patterns on Cardiometabolic Outcomes in the Transition to Adolescence: International Children’s Accelerometry Database 2.0. J Pediatr (2020)
• Bernhardsen GP, Stensrud T, Hansen BH, Steene-Johannesen J, Kolle E, Nystad W, Anderssen SA, Hallal PC, Janz KF, Kriemler S, Andersen LB, Northstone K, Resaland GK, Sardinha LB, van Sluijs EMF, Ried-Larsen M, Ekelund U; International Children’s Accelerometry Database (ICAD) Collaborators. Birth weight, cardiometabolic risk factors and effect modification of physical activity in children and adolescents: pooled data from 12 international studies. Int J Obes (2020)
• van Ekris E, Wijndaele K, Altenburg TM, Atkin AJ, Twisk J, Andersen LB, Janz KF, Froberg K, Northstone K, Page AS, Sardinha LB, van Sluijs EMF, Chinapaw M; International Children’s Accelerometry Database (ICAD) Collaborators. Tracking of total sedentary time and sedentary patterns in youth: a pooled analysis using the International Children’s Accelerometry Database (ICAD). Int J Behav Nutr Phys Act. (2020)
• Steene-Johannessen J, Hansen BH, Dalene KE, Kolle E, Northstone K, Møller NC, Grøntved A, Wedderkopp N, Kriemler S, Page AS, Puder JJ, Reilly JJ, Sardinha LB, van Sluijs EMF, Andersen LB, van der Ploeg H, Ahrens W, Flexeder C, Standl M, Shculz H, Moreno LA, De Henauw S, Michels N, Cardon G, Ortega FB, Ruiz J, Aznar S, Fogelholm M, Decelis A, Olesen LG, Hjorth MF, Santos R, Vale S, Christiansen LB, Jago R, Basterfield L, Owen CG, Nightingale CM, Eiben G, Polito A, Lauria F, Vanhelst J, Hadjigeorgiou C, Konstabel K, Molnár D, Sprengeler O, Manios Y, Harro J, Kafatos A, Anderssen SA, Ekelund U; Determinants of Diet and Physical Activity knowledge hub (DEDIPAC); International Children’s Accelerometry Database (ICAD) Collaborators, IDEFICS Consortium and HELENA Consortium. Variations in accelerometry measured physical activity and sedentary time across Europe – harmonized analyses of 47,497 children and adolescents. Int J Behav Nutr Phys Act (2020)
• Werneck AO, Silva DR, Oyeyemi AL, Fernandes RA, Steene-Johannesen J, Andersen LB, Northstone K, Sardinha LB, On behalf of the International Children’s Accelerometry Database (ICAD) Physical activity attenuates metabolic risk of adolescents with overweight or obesity: The ICAD Multi-country Study Int J Obes (2020)

• Renninger M, Hansen BH, Steene-Johannessen J, Kriemler S, Froberg K, Northstone K, Sardinha L, Anderssen SA, Andersen LB, Ekelund U; International Children’s Accelerometry Database (ICAD) Collaborators. Associations between accelerometry measured physical activity and sedentary time and the metabolic syndrome: A meta-analysis of more than 6000 children and adolescents. Pediatr Obes. (2019)

• Wijndaele K, White T, Andersen LB, Bugge A, Kolle E, Northstone K, Wedderkopp N, Ried-Larsen M, Kriemler S, Page AS, Puder JJ, Reilly JR, Sardinha LB, van Sluijs EMF, Sharp SJ, Brage S, Ekelund U, On behalf of the International Children’s Accelerometry Database (ICAD) Collaborators. Substituting prolonged sedentary time and cardiovascular risk in children and youth: a meta-analysis in the International Children`s Accelerometry Database (ICAD). Int J Behav Nutr Phys Act (2019)

• Dias KI, White J, Jago R, Cardon G, Davey R, Janz KF, Pate RR, Puder JJ, Reilly JJ, Kipping R. International Comparison of the Levels and Potential Correlates of Objectively MeasuredSedentary Time and Physical Activity among Three-to-Four-Year-Old Children. Int J Environ Res Public Health (2019)
• Kwon S, Andersen LB, Grøntved A, Kolle E, Cardon G, Davey R, Kriemler S, Northstone K, Page AS, Puder JJ, Reilly JJ, Sardinha LB, van Sluijs EMF, Janz KF. A closer look at the relationship among accelerometer-based physical activity metrics: ICAD pooled data. Int J Behav Nutr Phys Act (2019)
• Tarp J, Child A, White T, Westgate K, Bugge A, Grøntved A, Wedderkopp N, Andersen LB, Cardon G, Davey R, Janz KF, Kriemler S, Northstone K, Page AS, Puder JJ, Reilly JJ, Sardinha LB, van Sluijs EMF, Ekelund U, Wijndaele K, Brage S; International Children’s Accelerometry Database (ICAD) Collaborators. Physical activity intensity, bout-duration, and cardiometabolic risk markers in children and adolescents. Int J Obes (2018)
• Hansen BH, Anderssen SA, Andersen LB, Hildebrand M, Kolle E, Steene-Johannessen J, Kriemler S, Page AS, Puder JJ, Reilly JJ, Sardinha LB, van Sluijs EMF, Wedderkopp N, Ekelund U; International Children’s Accelerometry Database (ICAD) Collaborators. Cross-Sectional Associations of Reallocating Time Between Sedentary and Active Behaviours on Cardiometabolic Risk Factors in Young People: An International Children’s Accelerometry Database (ICAD) Analysis Sports Med. (2018)
• Atkin AJ, Biddle SJH, Broyles ST, Chinapaw M, Ekelund U, Esliger DW, Hansen BH, Kriemler S, Puder JJ, Sherar LB, van Sluijs EMF; International Children’s Accelerometry Database (ICAD) Collaborators. Harmonising data on the correlates of physical activity and sedentary behaviour in young people: Methods and lessons learnt from the international Children’s Accelerometry database (ICAD). Int J Behav Nutr Phys Act. (2017)
• Tarp J, Bugge A, Andersen LB, Sardinha LB, Ekelund U, Brage S, Møller NC. Does adiposity mediate the relationship between physical activity and biological risk factors in youth?: a cross-sectional study from the International Children’s Accelerometry Database (ICAD). Int J Obes (2017)
• Kuzik N, Carson V, Andersen LB, Sardinha LB, Grøntved A, Hansen BH, Ekelund U; International Children’s Accelerometry Database (ICAD) Collaborators. Physical Activity and Sedentary Time Associations with Metabolic Health Across Weight Statuses in Children and Adolescents. Obesity (2017) Oct;25(10):1762-1769. [full text]
• Harrison F, Goodman A, Van Sluijs EMF, Andersen LB, Cardon G, Davey R, Janz KF, Kriemler S, Molloy L, Page AS, Pate R, Puder JJ, Sardinha LB, Timperio A, Wedderkopp N, Jones AP. Weather and children’s physical activity; how and why do relationships vary between countries? Int J Behav Nutr Phys Act. (2017)
• Moore JB, Beets MW, Brazendale K, Blair SN, Pate RR, Andersen LB, Anderssen SA, Grøntved A, Hallal PC, Kordas K, Kriemler S, Reilly JJ, Sardinha LB. Associations of Vigorous-intensity Physical Activity with Biomarkers in Youth. Med Sci Sports Exerc. (2017)
• Mitchell JA, Dowda M, Pate RR, Kordas K, Froberg K, Sardinha LB, Kolle E, Page A. Physical Activity and Pediatric Obesity: A Quantile Regression Analysis. Med Sci Sports Exerc. (2017)
• Sherar LB, Griffin TP, Ekelund U, Cooper AR, Esliger DW, van Sluijs EM, Bo Andersen L, Cardon G, Davey R, Froberg K, Hallal PC, Janz KF, Kordas K, Kriemler S, Pate RR, Puder JJ, Sardinha LB, Timperio AF, Page AS. Association between maternal education and objectively measured physical activity and sedentary time in adolescents. J Epidemiol Community Health. (2016)
• Corder K, Sharp SJ, Atkin AJ, Andersen LB, Cardon G, Page A, Davey R, Grøntved A, Hallal PC, Janz KF, Kordas K, Kriemler S, Puder JJ, Sardinha LB, Ekelund U, Van Sluijs EM, on behalf of the International Children’s Accelerometry Database (ICAD) Collaborators. Age-related patterns of vigorous-intensity physical activity in youth: the International Children’s Accelerometry Database. Prev Med Reports (2016)
• Brazendale K, Beets MW, Bornstein DB, Moore JB, Pate RR, Weaver RG, Falck RS, Chandler JL, Andersen LB, Anderssen SA, Cardon G, Cooper A, Davey R, Froberg K, Hallal PC, Janz KF, Kordas K, Kriemler S, Puder JJ, Reilly JJ, SAlmon J, Sardinha LB, Timperio A, van Sluijs EMF, on behalf of the International Children’s Accelerometry Database (ICAD) Collaborators. Equating accelerometer estimates among youth: the Rosetta Stone 2. J Sci Med Sports (2016)
• Cooper AR, Goodman A, Page AS, Sherar LB, Esliger DW, van Sluijs EM, Andersen LB, Anderssen S, Cardon G, Davey R, Froberg K, Hallal P, Janz KF, Kordas K, Kreimler S, Pate RR, Puder JJ, Reilly JJ, Salmon J, Sardinha LB, Timperio A, Ekelund U. Objectively measured physical activity and sedentary time in youth: the International children’s accelerometry database (ICAD). Int J Behav Nutr Phys Act. (2015)
• Hildebrand M, Kolle E, Hansen BJ, Collings PJ, Wijndaele K, Kordas K,  Cooper AR, Sherar LB, Andersen LB, Sardinha LB, Kriemler S, Hallal P, Van Sluijs E, Ekelund U. Association between birth weight and objectively measured sedentary time is mediated by central adiposity: data in 10,793 youth from the International Children’s Accelerometry Database. Am J Clin Nutr (2015)
• Goodman A, Page AS, Cooper AR; International Children’s Accelerometry Database (ICAD) Collaborators. Daylight saving time as a potential public health intervention: an observational study of evening daylight and objectively-measured physical activity among 23,000 children from 9 countries. Int J Behav Nutr Phys Act (2014)
  • For press coverage, please see for example: BBC, Guardian
• Atkin AJ, Sharp SJ, Corder K, van Sluijs EM; on behalf of the International Children’s Accelerometry Database (ICAD) Collaborators. Prevalence and correlates of screen time in youth: an international perspective. Am J Prev Med (2014)
• Kwon S, Janz KF; International Children’s Accelerometry Database (ICAD) Collaborators. Tracking of accelerometry-measured physical activity during childhood: ICAD pooled analysis. Int J Behav Nutr Phys Act (2012)
• Ekelund U, Luan JA, Sherar LB, Esliger DW, Grew P, Cooper A. Moderate to Vigorous Physical Activity and Sedentary Time and Cardiometabolic Risk Factors in Children and Adolescents. JAMA (2012)
• Sherar L, Griew P, Esliger D, Cooper A, Ekelund U, Judge K, Riddoch C. International children’s accelerometry database (ICAD): Design and methods. BMC Public Health (2011)

Studies that have contributed data

UNITED STATES

– NHANES (wave 2003/2004 and 2005/2006)

– Project TAAG (Trial of Activity for Adolescent Girls)

– CHAMPS US (Physical Activity in Pre-School Children)

– Iowa Bone Development Study

BRAZIL

– 1993 Pelotas Birth Cohort

EUROPE

– European Youth Heart Study (Norway, Portugal, Estonia and Denmark)

– PEACH Project (Personal and Environmental Association with Children’s Health)

– Project MAGIC (Movement and Activity Glasgow Intervention with Children’s Health)

– ALSPAC (Avon Longitudinal Study of Parents and Children)

• ALSPAC publishing guidelines
• ALSPAC further info

– SPEEDY (Sport Physical Activity & Eating Behaviour: Environmental Determinants in Young People)

– CHAMPS UK (Children’s Health and Activity Monitoring Program)

– The Copenhagen School Children Intervention Study

– Belgium Pre-school Study

– Swiss Ballabeina Study

– Swiss Kinder-Sportstudie (KISS) Study

AUSTRALIA

– Project CLAN (Children Living in Active Neighbourhoods)

– Project HEAPS (Healthy Eating And Play Study)