Most people know that exercise can help beat type 2 diabetes, but one type of fitness regimen might work best, a new study shows.
Specifically, workouts that combine aerobic and resistance training exercises appear better at controlling blood sugar than either type of activity alone, researchers say.
The finding is new, because "most other studies have looked at just one kind of exercise, either aerobic or resistance," noted lead researcher Ronald J. Sigal, MD, an associate professor of medicine and cardiac sciences at the University of Calgary, in Alberta, Canada.
Dr. Sigal's team evaluated 251 adults, ages 39 to 70, with type 2 diabetes who did not exercise regularly. The participants were assigned to one of four groups: those who did 45 minutes of aerobic training three times a week, those who did 45 minutes of resistance training three times a week, those who did 45 minutes each of both forms of exercise three times a week, and those who did no exercise at all.
The aerobic group worked out on a treadmill or a bike at the gym. The resistance group also worked out at the gym doing seven different exercises on weight machines.
Dr. Sigal's team evaluated changes in Alc values—a measurement reflecting blood sugar concentrations over the previous two to three months. Alc is expressed as a percentage.
As expected, blood sugar control improved in all the exercise groups. In those who did either aerobic or resistance exercise, the Alc value declined by about 0.5% compared to the non-exercisers. Those who did both kinds of exercise had double that level of success, with their Alc value dropping by 0.97% compared to the non-exercising group. Non-exercisers experienced no change in their Alc values over the 26-week study.
The bottom line: "There is additional value to doing both resistance and aerobic exercise," according to Dr. Sigal.
He said the decrease of nearly 1% of Alc seen in the study "translates to a 15% to 20% reduction in risk of heart attack or stroke and a 25% to 40% reduced risk of other complications, such as retinopathy," an eye problem related to diabetes.
How does physical activity fight type 2 diabetes? According to Dr. Sigal, "exercise decreases insulin resistance. It makes the transport of glucose [blood sugar) more efficient."
Another expert said the study gives new information for people hoping to beat back diabetes. "Basically, aerobic and resistance training both do very well, and the combination does even better," said Cathy Nonas, RD, director of physical activity and nutrition for the New York City Department of Health and Mental Hygiene and a registered dietitian and certified diabetes educator.
But, she said, couch potatoes often need to ease into exercise to maintain a fitness regimen over time.
The study participants built up to their 45minute fitness sessions, Dr. Nonas noted, and the combination group ended up doing about 45 hours of exercise a week—an amount some might find daunting.
"I would never talk about 4.5 hours a week to someone who doesn't exercise at all," Dr. Nonas said. Rather, she encourages physical activity in any amount to start. "Anything you do is good," she said. Then she encourages people to slowly build up their time.
"I think this is a very uplifting study," she added. "It says whatever you do will have an effect.”