Influence of anthropometric characteristics on insulin responses to uphill and downhill walking in women
Horrigan, Laura Clare.
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Obesity is associated with insulin resistance as well as several leading causes of preventable death. Exercise is a lifestyle factor that decreases risk of these conditions. The type of exercise performed might play a role in the insulin response to exercise as well as a recommended post-exercise meal. Eccentric exercise is shown to increase insulin resistance while concentric is known to decrease insulin resistance. The purpose of this study was to determine if there are differences in post-exercise insulin levels between eccentric and concentric exercise conditions with a post-exercise meal, and the relationship with waist circumference (WC), a measure of central obesity. Participants were women (n =24), stratified into low (LWC) and high (HWC) waist circumference groups. Participants completed three test conditions: a 45-minute walk at -10% grade at 3.0MPH, a 45-minute walk at +10% grade at a speed that maintained 60% of estimated VO 2max, and a control. A mixed meal was consumed thirty minutes after completion of the test. Finger stick measures of glucose were taken at 0, right before consumption, and then 15, 30, 45, 60, 90, 120 minutes following the meal. Insulin, C-peptide, and glucose were measured pre-test and immediately, 8 hours, and 24 hours after completion of the test. Muscle soreness was measured when blood was collected. The HWC group had higher (p< 0.05) insulin across time points compared to the LWC group in the control and uphill conditions. C-peptide was greater (p<0.05) across time points for the HWC group in the control compared to the LWC group. The HWC group had greater (p<0.05) insulin at 60-minutes in response to the meal during the control condition than the LWC group. The LWC had greater (p<0.05) insulin at 60 minutes in the downhill compared to the control. Muscle soreness was increased (p<0.05) the most in response to the downhill condition. We conclude that waist circumference influenced insulin levels following exercise, where uphill walking improved indices of glycemic control for those of greater waist circumference while downhill walking worsened indices of glycemic control for those of a lower waist circumference.