Weight training may help to prevent diabetes, a new study shows.
Doctors routinely recommend regular aerobic exercise to reduce the risk of Type 2 diabetes. But for those who prefer resistance training to running on a treadmill, a new study shows that weight training can protect against diabetes as well.
The researchers found that doing at least two and a half hours a week of either aerobic exercise or weight training substantially lowered the risk of Type 2 diabetes. But more than anything else the study provided an endorsement for doing both. Those who combined weights with cardio had the greatest reduction in risk compared with their non-exercising peers. The study subjects were men, but the researchers believe the results apply to women as well.
“We found that in the group that did fairly large amounts of both, there was about a 60 percent reduced risk of diabetes, which is huge,” said Dr. Walter Willett, chairman of the department of nutrition at the Harvard School of Public Health and an author of the study. “It’s clear that the best thing is to get a combination of the two. But some people really can’t get aerobic exercise in their life, and we found that even a small amount of resistance exercise can make a difference.”
Plenty of research has shown that regular physical activity greatly lowers the odds of developing Type 2 diabetes, a disease that afflicts nearly 26 million Americans, many of them overweight. While there have been studies showing that resistance training can help improve control of blood sugar levels in people with Type 2 diabetes, nearly all of the research on preventing the condition has involved aerobic exercise.
So to figure out whether time spent in the weight room could have the same preventive benefits as other exercise, Dr. Willett and his colleagues analyzed data on 32,000 men who were followed for almost two decades as part of the Health Professionals Follow-Up Study, a long-running project looking at the health of medical professionals. The study, published in Archives of Internal Medicine, was designed to be the male complement to the well known Nurses’ Health Study, which includes only women.
Poring over data from an 18-year study window, the researchers found that 2,278 of the men developed Type 2 diabetes. After controlling for many variables, including age, body mass and alcohol intake, the researchers found that engaging in aerobic exercise for at least 150 minutes a week lowered the risk of developing the disease by 52 percent. Doing the same amount of weight training, meanwhile, was associated with a 34 percent lower risk, independent of any aerobic exercise. But doing both led to the greatest reduction in risk.
Dr. Willett said the mechanism behind weight training’s beneficial effect on diabetes most likely stems from its effect on insulin receptors. Resistance training builds muscle mass, a process that can take weeks. But it also improves the sensitivity of insulin receptors, so that muscle cells can absorb their fuel, glucose, more easily. This process results almost immediately from doing resistance exercise, and the effect can last for days.
“You’re essentially allowing the fuel to pass into the muscles more quickly, which is exactly what you need to happen if you’re putting those muscles to use,” Dr. Willett said.
The study found the largest effect among men doing the most resistance training, but even 10 minutes a day of resistance work — whether at the gym or at home doing push-ups or using resistance bands — is enough to produce a benefit, he added.
The study did have a limitation in that it involved only men, and most of them were white. But Dr. Willett said he was “virtually sure” the results were universally applicable. Just as aerobic exercise benefits everyone, he said, weight training should as well.
“Muscle physiology is pretty similar across ethnic groups and gender,” he said. “There may be some subtle variations, but the basic biology is similar.”