Diabetes affects 11 percent of African American adults, and one in four black women over 55 is living with the condition. It’s well known that exercise can control blood sugar, but should you do strength training or aerobic exercise? High reps with low weight, or vice versa?

Researchers at the University of Calgary and the University of Ottawa examined 251 people ages 39 to 70—all with type 2 or adult onset diabetes. Researchers broke participants into four groups: resistance (weight) training only, aerobic exercise only, a group that did both and one that did neither. Real Health spoke with Dr. Ronald Sigal, associate professor of medicine and cardiac sciences at the University of Calgary and lead author of the study, which was published in the September 18 issue of Annals of Internal Medicine.

You found that the combination of weight training and aerobics is the most beneficial in controlling blood sugar in people with type 2 diabetes. Why?
Well, both types of exercise do different things. The aerobic exercise, the cardio type of exercise, makes each muscle fiber produce glucose more efficiently and makes them more metabolically active. And the weight lifting type of exercise makes each fiber larger. So it’s the combination of muscle fibers being larger and more metabolically active.

And what does the ideal exercise for controlling diabetes consist of?
That’s a good question. We didn’t systematically go through all the different possible types of workouts. Certainly, what we aimed to do was have an adequate amount of each kind of exercise. By the second half of the study the combination group was doing 45 minutes at 75 percent of their maximum heart rate for the aerobic exercise. They were mostly middle-aged and older people who were clearly out of shape to start with. So for most of them that was walking on a treadmill, usually on an angle, rather than jogging.

For some of the participants in better shape it was jogging, or some chose to use a bicycle or an elliptical machine. And the important thing with the weight lifting, studies like ours that have had the better results have tended to have low [numbers of repetitions with] higher weights, rather than high [numbers of repetitions with] low weight. So it’s something people have to build up to. But basically each session would exercise each of the major muscle groups. And there were seven different resistance exercises per session, plus abdominal crunches. And they did three sets of each of them, with eight repetitions at the weight they could lift them.

What’s really interesting about your study is that as recently as a few years ago, the American Diabetes Association recommended against weight training. Why the change?
Well, there never really was any evidence to back up that older position. That was originally drafted in the late ’80s, I think, and never revised. And that was a time when there was absolutely no evidence one way or another. People’s concern was that people with diabetes often have blood pressure problems. And the idea was that the blood pressure might go too high and that would be dangerous. But in fact, that seems to not really be a problem.

Since these exercises are a proven way to control blood sugar, could they be used as a preventative measure for people who are at risk but do not currently have diabetes?
That hasn’t been directly tested, but there’s every reason to believe they could be. What works well in type 2 diabetes for controlling sugar would also work well for preventing it. Because they both would make glucose metabolism work better, it would make sense if you’re using your body’s own insulin. So chances are, it would be the best way.

What would you recommend for people that can’t necessarily get to the gym?
The most successful form of exercise for most people is walking. So that is certainly an excellent place to start. Now in terms of getting the best results from weight lifting, you really do need to get to a gym. Unless you have a huge house and a huge budget and can afford a whole array of equipment. We and others have tried home-based resistance exercise to see if that would work. It’s better than nothing, but it’s not as good as the results that we get with the gym. Probably because it’s just unfeasible to have the full array of higher-quality equipment that works each individual muscle group optimally. And while there’s certainly something to gain from things like push-ups and sit-ups, it’s hard to sustain interest in them. That’s the problem.

Also, in terms of weight training, it’s important to be taught and be supervised by someone who knows what he or she is doing, to make sure you’re progressing well and not doing it in a way where you’ll injure yourself.

Who should people consult before they strap on their running shoes or hit the gym?
Probably his or her own doctor is the best person to start with, particularly for someone who is middle-aged and older. It’s probably a bit less of an issue for a younger person.

What about people with other health conditions such as heart disease?
Within this study, we performed comprehensive exam on participants, including a cardiac stress test to make sure that there wasn’t a heart problem we were missing. We made sure they had eye checks also, to make sure that there wasn’t unstable diabetic eye disease.

And what should people keep in mind before deciding if an exercise program is right for them in tackling blood sugar?
Well, what I think we’ve demonstrated is that the exercise clearly is helpful. It clearly improves glucose control for people with type 2 diabetes. And for someone who wants to maximize the benefit, it would be well worthwhile doing both kinds of exercise. Even though it may involve some additional time managements, and some additional structuring of time to get to a gym.