The Benefits of Light Exercise
Why light exercise may equal—or trump—more intense workouts
Marc Hamilton, PhD
Physiologist, director of the Texas Obesity Research Center, and professor at the University of Houston
ADA Research Funding
Study after study has shown that moderate exercise is beneficial for people with diabetes. In its 2016 Standards of Medical Care in Diabetes, the American Diabetes Association recommends adults get 150 minutes of moderate to vigorous exercise per week and identifies aerobic exercise and strength training as important factors for managing diabetes.
Yet that advice goes largely unheeded. One in 10 American adults manages to do the recommended amount of moderate to vigorous exercise each week; even fewer people with diabetes do the recommended amount of exercise. For the elderly, people who are obese, or those with heart problems, intense workouts might even be dangerous.
That’s why University of Houston physiologist Marc Hamilton, PhD, is studying the benefits of easy exercise instead. “Traditionally, the recommendation has been that activity must be at least in the moderate category to count for health,” Hamilton says. “But anything that gets you sweaty and breathing hard is something we’re not focusing on for potent novel solutions.”
In fact, Hamilton says, the benefits of intense workouts that get your heart pumping hard may be oversold—particularly when it comes to delivering health benefits to people with diabetes, where controlling blood glucose is more important than running faster or even losing weight. “Moderate to vigorous exercise is healthy, but it’s not protecting us from the other 23.5 hours a day when we’re not exercising,” he says. “It’s more important to keep your metabolism burning all day long to reap the benefits of muscular activity.”
The best way to do that, he says, is with light exercise all day, instead of a single hard workout. Even completing household chores may be enough to do the trick. “That’s a paradigm shift,” Hamilton says.
As a public health strategy, encouraging people to sit less might be more effective than encouraging them to run more 5Ks, too. Light exercise isn’t just easier to fit into daily life—it may well be better in the long run for your blood glucose levels. “Lower intensity leads to much higher frequency and duration,” Hamilton says. “We’re looking for a scalable solution for millions of people. It’s something that’s not a lot of effort and doesn’t make them tired or sore.”
Over the past decade, Hamilton’s lab has learned more about when and where the body gets its energy. Our muscles use glucose as fuel, but it’s stored in different places. Some is stockpiled in the muscle cells; much of the rest is in the blood.
When your heart begins pounding and you start to sweat, your muscles need big gulps of fuel, as fast as possible. They reach first for the fuel stored in the cells themselves. But when you’re moving just a little bit—standing up or walking slowly, for example—that activates a different set of muscle cells, which take their fuel from the bloodstream a sip at a time. “During lower-intensity activity, the primary fuel comes from the blood. That’s great for health,” Hamilton says.
The benefits of light activity for people with diabetes could be particularly high. Lots of light exercise could lower blood glucose levels overall, with fewer fluctuations throughout the day. “For diabetes treatment and prevention, lower intensity could work more efficiently,” Hamilton says. “For decades, studies only looked at moderate exercise. That didn’t mean light wasn’t good, just that no one looked at it,” Hamilton says. “That’s started to change.”
Hamilton is testing the theory with the help of a grant from the ADA. He’s working with a group of about 24 people with diabetes. First, he and his team measure important indicators, such as blood insulin and blood glucose levels. Participants are then fitted with sophisticated motion trackers that record whether they’re standing, walking, sitting, or lying down.
After working with his research team to find ways to fit light activity into their days, participants come back after three months and are measured again. So far, the results have been promising. “Light exercise isn’t a stepping stone to heavy. It’s in many ways more potent than heavy,” Hamilton says. “Think of the tortoise and the hare—sustained activity is going to win the race.”
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