Staying Strong: Health and Fitness for Older Adults

A new study from the University of Calgary has found that doing both aerobic activity (such as treadmill walking, cycling, or jogging) combined with resistance training can lower blood sugar in people with Type 2 Diabetes. The study was published in the September 18 issue of the Annals of Internal Medicine.

Researchers in Ottawa conducted a randomized control study of 251 people aged 39 to 70 with Type 2 Diabetes. The subjects were divided into 4 groups: those who engaged in aerobic exercise (cycling, jogging, walking), those who did resistance training (weight lifting), those who did both, and those who did not exercise (control group). To be in an exercise group, subjects participated in 45 minutes of each type activity (aerobic exercise, weight training, or both) three times a week for 22 weeks at local YMCAs. The researchers examined subjects' hemoglobin A1c values after 6 months. Hemoglobin A1c is a measure of blood sugar concentration. Having values of 7 or under is considered good in people with Type 2 Diabetes. People without diabetes typically have hemoglobin A1c values of 4 to 6 percent.

So how did the groups do? The group who did only aerobic exercise experienced an average drop in hemoglobin A1c of 0.51 percentage points. The resistance training group saw a 0.38 percentage point drop. But the group who participated in both aerobic exercise and resistance training saw about double the improvement of the other two groups, with an average 0.97 percentage point drop. Although these numbers may not seem significant, the researchers explain that a one percentage drop in hemoglobin A1c levels is associated with a 15% to 20% reduction in the risk of a stroke, heart attack, or other major cardiovascular event, and a 37% reduction in the risk of microvascular complications such as blindness, kidney failure, or peripheral neuropathy (numbness or tingling in the extremities).

The researchers conclude that "either aerobic exercise or resistance exercise alone improves blood sugar control in patients with type 2 diabetes, but a program of longer exercise sessions that includes both types of exercise results in better blood sugar control after 6 months...Therefore, persons with type 2 diabetes who wish to improve their metabolic control through physical activity should be encouraged to perform both aerobic and resistance training."

Notable in the study was the strong level of adherence among the participants in the exercise program. These adherence levels were much higher than is usually seen in the general population (87% compared to 33%). The researchers credited this to the fact that the participants followed a formal exercise program designed by an exercise specialist, who met regularly with each participant. Participants were expected to follow the training plan and keep a log of their activities. This encouraged them to attend every session during the 22 week period.

This study shows not only that both aerobic and weight training combined has a positive effect on blood glucose levels in people with Type 2 Diabetes, but also that the benefits of exercise is best realized when performed regularly according to a training plan. I encourage anyone wishing to begin an exercise program to consult with an exercise specialist, such as a Certified Personal Trainer, who can tailor a program to your own needs.

For more information on Diabetes and exercise, please see this previous column.

Sigal, R.J. et al (2007). Effects of Aerobic Training, Resistance Training, or Both on Glycemic Control in Type 2 Diabetes. Annals of Internal Medicine, 147, 357-369.

Get on a treadmill, lift some weights to reduce blood sugar!