Research Study Abstract

Improving wear time compliance with a 24-hour waist-worn accelerometer protocol in the International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE)

  • Published on Feb. 11, 2015

Background: We compared 24-hour waist-worn accelerometer wear time characteristics of 9–11 year old children in the International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE) to similarly aged U.S. children providing waking-hours waist-worn accelerometer data in the 2003–2006 National Health and Nutrition Examination Survey (NHANES).

Methods: Valid cases were defined as having ≥4 days with ≥10 hours of waking wear time in a 24-hour period, including one weekend day. Previously published algorithms for extracting total sleep episode time from 24-hour accelerometer data and for identifying wear time (in both the 24-hour and waking-hours protocols) were applied. The number of valid days obtained and a ratio (percent) of valid cases to the number of participants originally wearing an accelerometer were computed for both ISCOLE and NHANES. Given the two surveys’ discrepant sampling designs, wear time (minutes/day, hours/day) from U.S. ISCOLE was compared to NHANES using a meta-analytic approach. Wear time for the 11 additional countries participating in ISCOLE were graphically compared with NHANES.

Results: 491 U.S. ISCOLE children (9.92±0.03 years of age [M±SE]) and 586 NHANES children (10.43 ± 0.04 years of age) were deemed valid cases. The ratio of valid cases to the number of participants originally wearing an accelerometer was 76.7% in U.S. ISCOLE and 62.6% in NHANES. Wear time averaged 1357.0 ± 4.2 minutes per 24-hour day in ISCOLE. Waking wear time was 884.4 ± 2.2 minutes/day for U.S. ISCOLE children and 822.6 ± 4.3 minutes/day in NHANES children (difference = 61.8 minutes/day, p < 0.001). Wear time characteristics were consistently higher in all ISCOLE study sites compared to the NHANES protocol.

Conclusions: A 24-hour waist-worn accelerometry protocol implemented in U.S. children produced 22.6 out of 24 hours of possible wear time, and 61.8 more minutes/day of waking wear time than a similarly implemented and processed waking wear time waist-worn accelerometry protocol. Consistent results were obtained internationally. The 24-hour protocol may produce an important increase in wear time compliance that also provides an opportunity to study the total sleep episode time separate and distinct from physical activity and sedentary time detected during waking-hours.

Trial registration: NCT01722500


  • Catrine Tudor-Locke 1
  • Tiago V Barreira 1,2
  • John M Schuna 1,3
  • Emily F Mire 1
  • Jean-Philippe Chaput 4
  • Mikael Fogelholm 5
  • Gang Hu 1
  • Rebecca Kuriyan 6
  • Anura Kurpad 6
  • Estelle V Lambert 7
  • Carol Maher 8
  • José Maia 9
  • Victor Matsudo 10
  • Tim Olds 8
  • Vincent Onywera 11
  • Olga L Sarmiento 12
  • Martyn Standage 13
  • Mark S Tremblay 4
  • Pei Zhao 14
  • Timothy S Church 1
  • Peter T Katzmarzyk 1
  • ISCOLE Research Group


  • 1

    Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge 70808, LA, USA

  • 2

    Syracuse University, Syracuse, USA

  • 3

    Oregon State University, Corvallis, USA

  • 4

    Children’s Hospital of Eastern Ontario Research Institute, Ottawa, Canada

  • 5

    University of Helsinki, Helsinki, Finland

  • 6

    St. Johns Research Institute, Bangalore, India

  • 7

    University of Cape Town, Cape Town, South Africa

  • 8

    University of South Australia, Adelaide, Australia

  • 9

    CIFI2D, Faculdade de Desporto, University of Porto, Porto, Portugal

  • 10

    Center of Studies of the Physical Fitness Research Laboratory from Sao Caetano do Sul (CELAFISCS), Sao Paulo, Brazil

  • 11

    Kenyatta University, Nairobi, Kenya

  • 12

    School of Medicine, Universidad de los Andes, Bogota, Colombia

  • 13

    University of Bath, Bath, UK

  • 14

    Tianjin Women’s and Children’s Health Center, Tianjin, China


International Journal of Behavioral Nutrition and Physical Activity


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