Objectively Measured Time Spent Sedentary Is Associated With Insulin Resistance Independent of Overall and Central Body Fat in 9- to 10-Year-Old Portuguese Children

  1. Luis B. Sardinha, PHD1,
  2. Lars Bo Andersen, PHD2,
  3. Sigmund A. Anderssen, PHD2,
  4. Ana L. Quitério, MSC1,
  5. Rui Ornelas, MSC3,
  6. Karsten Froberg, PHD4,
  7. Chris J. Riddoch, PHD5 and
  8. Ulf Ekelund, PHD67
  1. 1Faculty of Human Movement, Technical University of Lisbon, Lisbon, Portugal
  2. 2Department of Sports Medicine, Norwegian School of Sports Sciences, Oslo, Norway
  3. 3Department of Physical Education and Sport, University of Madeira, Madeira, Portugal
  4. 4Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
  5. 5Department of Sport and Exercise Science, Bath University, Bath, U.K
  6. 6Medical Research Council Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, U.K.
  7. 7School of Health and Medical Sciences, Örebro University, Örebro, Sweden
  1. Address correspondence and reprint requests to Ulf Ekelund, Medical Research Council Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Box 285, CB2 0QQ, Cambridge, U.K. E-mail: ulf.ekelund{at}mrc-epid.cam.ac.uk

Abstract

OBJECTIVE—We examined the independent relationships between objectively measured physical activity and insulin resistance in Portuguese children.

RESEARCH DESIGN AND METHODS—This is a school-based, cross-sectional study in 147 randomly selected girls (aged 9.8 ± 0.3 years; 27.8 ± 9.3% body fat) and 161 boys (aged 9.8 ± 0.3 years; 22.0 ± 9.2% body fat). Physical activity was assessed by the Actigraph accelerometer for 4 days and summarized as time spent sedentary (accelerometer counts <500/min), in light-intensity (accelerometer counts 500–2,000/min), and in moderate- and vigorous-intensity activity (accelerometer counts >2,001/min). We measured total and central fat mass by dual-energy X-ray absorptiometry. Insulin resistance was expressed as the homeostasis model assessment score.

RESULTS—Time (min/day) spent sedentary was significantly and positively associated with insulin resistance (β-coefficient = 0.001 [95% CI 0.0002–0.002]; P = 0.013). Time spent in moderate- and vigorous-intensity physical activity (−0.002 [−0.003 to −0.001]; P = 0.0009) and overall physical activity (−0.001 [−0.008 to 0.003]; P < 0.0001) were significantly and inversely associated with insulin resistance. All associations remained statistically significant, although they were attenuated after further adjustments for sex, birth weight, sexual maturity, and total or central fat mass (P < 0.03).

CONCLUSIONS—Physical activity is associated with insulin resistance independent of total and central fat mass in children. Our results emphasize the importance of decreasing sedentary behavior and increasing time spent in moderate- and vigorous-intensity activity in children, which may have beneficial effects on metabolic risk factors regardless of the degree of adiposity.

Footnotes

  • Published ahead of print at http://care.diabetesjournals.org on 10 December 2007. DOI: 10.2337/dc07-1286.

    The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C Section 1734 solely to indicate this fact.

    • Accepted December 1, 2007.
    • Received September 16, 2007.
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  1. Diabetes Care vol. 31 no. 3 569-575
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