Physical Activity, Physical Fitness, and Insulin and Glucose Concentrations in an Isolated Native Canadian Population Experiencing Rapid Lifestyle Change

  1. Andrea M. Kriska, PHD1,
  2. Anthony J.G. Hanley, PHD2,
  3. Stewart B. Harris, MPH, MD, CCFP, ABPM3 and
  4. Bernard Zinman, MD, CM, FRCP(C), FACP2
  1. 1Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania
  2. 2Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
  3. 3Centre for Studies in Family Medicine, University of Western Ontario, London, Ontario, Canada

    Abstract

    OBJECTIVE—Little is known about the relation of physical activity and physical fitness to insulin resistance and glucose intolerance in isolated subarctic Native Canadian populations. The purpose of this effort was to examine the relation between activity and fitness and obesity and glucose concentrations in such a unique population.

    RESEARCH DESIGN AND METHODS—This study describes 530 men and women from the community of Sandy Lake, Ontario, located in the boreal forest region of central Canada. Fasting blood glucose and insulin concentrations were determined after an overnight fast. Past year physical activity levels were assessed using a modified version of an interviewer-administered questionnaire. Maximal oxygen uptake, a measure of cardiovascular fitness, was estimated using a submaximal step test.

    RESULTS—Total (leisure and occupational) physical activity and physical fitness were significantly associated with fasting insulin concentrations after adjusting for age, BMI or percent body fat, waist circumference, and fasting glucose concentration in men but not in women. The relations between physical activity, fitness, and fasting glucose concentrations were not as strong or as consistent as they were when fasting insulin concentration was the dependent variable.

    CONCLUSIONS—In this isolated Native Canadian community, both physical activity and fitness were independently associated with fasting insulin concentrations, suggesting a beneficial role of physical activity/fitness on insulin sensitivity that is separate from any influence of activity on body composition. The fact that this relation was found in men but not in women is most likely explained by issues related to the measurement of activity and fitness in this study and the fact that the women in this population appear to be less active than the men.

    Footnotes

    • Address correspondence and reprint requests to Andrea M. Kriska, PhD, University of Pittsburgh, GSPH, 130 DeSoto St., Pittsburgh, PA 15261. E-mail: aky{at}pitt.edu.

      Received for publication 14 March 2001 and accepted in revised form 6 July 2001.

      A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.

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