Objectively Measured Sedentary Time May Predict Insulin Resistance Independent of Moderate- and Vigorous-Intensity Physical Activity

  1. Hendrik J.F. Helmerhorst1,2,
  2. Katrien Wijndaele1,
  3. Søren Brage1,
  4. Nicholas J. Wareham1 and
  5. Ulf Ekelund1
  1. 1Medical Research Council Epidemiology Unit, Cambridge, U.K.;
  2. 2Department of Endocrinology and Metabolism, Faculty of Medicine, Academic Medical Center, University of Amsterdam, the Netherlands.
  1. Corresponding author: Ulf Ekelund, ulf.ekelund{at}mrc-epid.cam.ac.uk.


OBJECTIVE To examine the prospective association between objectively measured time spent sedentary and insulin resistance and whether this association is independent of moderate- and vigorous-intensity physical activity (MVPA) and other relevant confounders.

RESEARCH DESIGN AND METHODS This was a population-based study (Medical Research Council Ely study) in 376 middle-aged adults (166 men; 210 women) over 5.6 years of follow-up. Physical activity and sedentary time were measured objectively by individually calibrated minute-by-minute heart rate monitoring at both baseline and follow-up. Sedentary time was calculated as the heart rate observations (in minutes) below an individually predetermined threshold (flex heart rate) and expressed as a percentage of total monitored time during waking hours over 4 days. The percentage of time spent above 1.75 × resting heart rate represented MVPA. Fasting plasma insulin was used as a surrogate measure of insulin resistance.

RESULTS Time spent sedentary at baseline was significantly and positively associated with log fasting insulin at follow-up (β = 0.003, 95% CI 0.0006–0.006, P = 0.015) independent of baseline age, sex, fat mass, fasting insulin, smoking status, and follow-up time. After further adjustment for MVPA, this association was somewhat strengthened (β = 0.004, 95% CI 0.0009–0.006, P = 0.009).

CONCLUSIONS Time spent sedentary predicts higher levels of fasting insulin independent of the amount of time spent at moderate- and vigorous-intensity activity levels. This highlights the importance of reducing sedentary time in order to improve metabolic health, possibly in addition to the benefits associated with a physically active lifestyle.


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    • Received December 22, 2008.
    • Accepted April 26, 2009.
  • Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.org/licenses/by-nc-nd/3.0/ for details.

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  1. Diabetes vol. 58 no. 8 1776-1779
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