Vigorous Exercise Linked to Improved Glucose Tolerance

A new study finds that intense exercise—but not moderate activity—is associated with improved glucose tolerance.

In an effort to determine the separate effects of exercise amount and intensity on abdominal obesity and glucose tolerance, researchers randomized 300 obese adults to 1 of 4 interventions: no exercise; a low-amount, low-intensity exercise; high-amount, low-intensity exercise; and high-amount, high-intensity exercise. All exercise interventions included 5 weekly sessions on a treadmill.
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Overall, 217 participants completed the intervention. The mean exercise time per session was 31 minutes for the low-intensity, low-amount group; 58 minutes for the high-amount, low-intensity group; and 40 minutes for the high-amount, high-intensity cohort. Daily unsupervised physical activity and sedentary time did not change in any exercise group versus control.

The authors, including researchers from Queen’s University in Kingston, Ontario, Canada, measured waist circumference and 2-hour glucose level (primary outcomes) as well as cardio-respiratory fitness and measures of insulin action (secondary measurements). After 24 weeks, all exercise groups saw waist circumference reduced by approximately 4.5 cm compared to the control group.

In addition, the investigators saw reductions in 2-hour glucose tolerance test levels in the high-amount, high-intensity groups compared to the control and low-amount, low-intensity exercise groups, while glucose tolerance did not significantly differ across the low-intensity and control groups.

While maintaining that the clinical importance of reducing 2-hour glucose levels in non-diabetic adults remains undetermined, the authors note that participants were surprised by the ease with which they achieved a high-intensity exercise level, and say that higher intensity levels of exercise can be achieved by simply increasing the incline while walking on a treadmill, or walking at a brisker pace. 

—Mark McGraw

Reference

Ross R, Hudson R, et al. Effects of Exercise on Obesity and Glucose Intolerance. Ann Intern Med. 2015.