HealthDay News — For older and otherwise inactive people, short bouts of moderately strenous walking in the morning and after meals improves 24-hour glycemic control, study findings suggest.
Compared with a baseline day of no walking, sustained walking in the morning or after a meal at three metabolic equivalents (METS) signifantly improved 24-hour glycemic control (P<0.05) in older inactive adults, Loretta DiPietro, PhD, from the George Washington University School of Public Health in Washington, D.C., and colleagues reported in Diabetes Care.
Post-meal walking was significantly more effective than sustained morning or afternoon walking for lowering three-hour post-dinner glucose (P<0.01), they also found.
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Older adults are at risk for hyperglycemia and diabetes due to aging- and disuse-related insulin resistance. Exercising can help supplement insulin in older patients with low insulin secretion, according to the researchers, and the time of day exercise is initiated can determine how well this effect controls insulin.
This study compared the effectiveness of three 15-minute bouts of post-meal walking with 45 minutes of sustained walking in a cohort of 10 inactive older (≥60 years of age) participants with a fasting blood glucose concentration between 105 and 125 mg dL−1. Participants had a mean age of 69 years, were considered class I obese (mean BMI 30 mg/kg2), and more than 40% had fat distributed around their truncal region.
Baseline screening included a fasting blood sample on undiagnosed diabetes and risk for impaired glucose tolerance, and body composition analysis.
Three randomly ordered exercise protocols were completed, spaced four weeks apart. The protocols were conducted over 48 hours and included a control day followed by a second day engaging in post-meal walking for 15 minutes or 45 minutes of sustained walking in the morning or afternoon.
On the control day, participants were asked to remain inactive in an experiment room that contained a bed, toilet, sink, treadmill, television and personal computer. Participants had fasting blood sample drawn and underwent continous subcutaneous glucose monitoring. Blood samples were also taken before and 30 minutes after meals to measure post-meal response to insulin.
On the exercise day, participants had a finger stick blood sample drawn, were given breakfast and completed one of the three exercise paramaters on a treadmill at three METS. Pre- and postmeal blood samples were taken in the same way as the control day.
Average 24-hour glucose concentrations were significantly reduced in both the 15-minute post-meal walking (P<0.03) and 45-minute walk (P<0.05) conditions, and both study conditions lowered 3-hour post-lunch glucose concentrations, though differences were not significant.
Only the 15-minute post-meal walking conditions significantly reduced three-hour post-dinner glucose levels (P<0.01) and three-hour area under the curve for dinner (P<0.03) vs. control. There was also an association between improvement in three-hour post-dinner glucose concentrations with 24-hour glucose improvement (P<0.001). This association was not seen with three-hour post-lunch glucose concentrations or fasting blood glucose.
“Given the excess disease burden associated with hyperglycemia in older age, and the recognized value of non-communicable disease prevention, there are enormous public health benefits to designing exercise programs that are enjoyable and effective within the populations needing them the most,” the researchers concluded.
Study limitations included the small, relatively-healthy sample, and lack of statistical power and generalizablility.
