For obese people who sit for most of the day, replacing some sitting time with standing, slow walking or slow cycling reduces average blood sugar across the day and into the night, a small study finds.
"Anything you can do to bring down glucose readings throughout the day is a good thing," said senior author Glenn Gaesser of the School of Nutrition and Health Promotion at Arizona State University in Phoenix. "We chose a typical workday because a large number of Americans spend a lot of time sitting at an office desk, and a number of (studies) indicate sitting is a health hazard, so we reckoned that trying to alleviate that by either standing or walking or cycling would help," Gaesser told Reuters Health.
The researchers studied nine overweight or obese adults who wore continuous blood sugar monitors and blood pressure monitors during their regular, mostly-sitting eight-hour workday. One week later, participants gradually replaced some of that sitting time with standing, in intervals of 10 to 30 minutes for a total of two and half hours per day. The following week, the same amount of sitting time was replaced with walking at a treadmill desk at a pace of one mile per hour. In the fourth week, the intervals were spent cycling on a stationary bike retrofitted to a workstation, also at an extremely slow pace with low energy expenditure. Average 24-hour glucose was lower for standing and walking than for sitting, and was lowest on the cycling days, the researchers report in Medicine and Science in Sports and Exercise. There was a similar pattern during the hours right after eating and even during overnight hours, with people having sustained lower blood sugar overnight after days they had cycled.
This is "not wholly surprising," because other research in the last few years has shown that breaking up prolonged sitting has benefits on glucose over the course of a day, said Dr. Daniel Bailey of the University of Bedforshire in the U.K., who was not part of the study. It's uncertain if the difference in blood sugar would have clinical significance or reduce metabolic risk, but that would be more likely for walking and cycling than for standing, which only resulted in a small reduction, Bailey told Reuters Health by email. "Studies with larger groups would be needed before we could say these findings would apply to overweight people in general," he said. But it's likely that overweight or prediabetic people may benefit more from breaking up periods of sitting than healthy-weight people, he said.
"We found that the overall reduction in blood sugar throughout the 24-hour day was typically 5 percent to 12 percent, with the greatest effect being in cycling," Gaesser said.
After a meal of carbohydrates, most blood sugar is disposed of in skeletal muscle, and muscle contractions increase insulin activity and glucose uptake, which helps to lower blood sugar, he said. "For low-level activity throughout the workday, the effect lasts well after the last exercise bout at 4:30 or 5:00 in the afternoon," continuing into sleep, he said. Breaks in sedentary time are good, even if you don't have access to a walking or cycling workstation, Gaesser said.
© Thomson Reuters 2016
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