This article was first posted on May 31, 2013.
We all know exercise is good for us. Running, biking, weight lifting, or yoga—moving our bodies makes us healthier. And research at Joslin is clarifying why. The lab of Laurie Goodyear, Ph.D. studies what exercise does to our bodies on the molecular level, both after one exercise session and after making exercise a routine part of life.
When you exercise aerobically once—take one run, say, or swim 50 laps—your body experiences immediate benefits. This single bout of exercise, or acute exercise as it’s referred to in Dr. Goodyear’s lab, increases the amount of fuel your muscles need to keep working. And that fuel usually comes in the form of blood glucose, helping to clear the bloodstream of excess sugar.
Muscle is home to proteins called glucose transporters. They function as their name suggests—transporting glucose from the blood stream into the muscle. They usually live deep inside the muscle cells, but exercise turns on signals in the cells that call the transporters to the surface, allowing them to take up all the glucose muscles need to keep powering through the workout.
Benefits extend post-acute exercise, too. “Insulin works a lot better after exercise,” said Dr. Goodyear. “You can more readily take up blood sugar into your tissues.” The effect can last up to 24 hours after exercise.
“You don’t have to be highly trained for these responses to occur,” said Dr. Goodyear. Any form of exercise, even walking, helps; however, the more intense the exercise session the more benefit your body gets.
Studies have mostly focused on these acute exercise effects in aerobic exercise (the movement of large muscles and muscle groups that get your heart beating fast). Acute strength training also seems to provide these benefits, though the effects have not been as thoroughly studied.
Chronic exercise is exercise happening on a regular basis, or at least three sessions per week. People getting the recommended amount of physical activity each week, for example, are chronic exercisers.
If acute exercise has good benefits, chronic exercise is even better because you reap the short- and long-term effects. Routine cardio can actually change the amount of certain proteins in your body—including those glucose transporters that get activated with each single bout of exercise. The more glucose transporters you have, the more efficiently your body takes up glucose from the bloodstream.
And it’s not just muscle tissue that sees benefits. Almost all tissues in your body are modified for the better when you make exercise a regular part of your life—everything from your heart, pancreas, blood vessels, and even your body’s fat.
Chronic strength training is “just as important to overall health,” said Dr. Goodyear. Working your muscles against resistance like bands, machines, or free weights maintains muscle and bone mass. The more muscle mass you have, the more glucose gets taken up.
Also, “muscle utilizes more energy even in a resting state” than fat,” said Dr. Goodyear. So more muscle mass can mean a higher basal metabolic rate, which translates to more calories burned even when you’re just sitting around.
“Exercise is critical for everyone, but especially for those with diabetes,” said Dr. Goodyear. Given the increasing awareness that there is a link between Type 2 diabetes and cancer and cognitive function, including Alzheimer’s, it is especially important to mitigate the effects of diabetes by exercising. In fact, there is now strong evidence that there are lower rates of certain forms of cancers and Alzheimer’s in people who regularly exercise.
And if you aren’t losing weight, don’t quit! The molecular benefits of exercise are independent of weight loss. Studies have shown that people with high BMIs and a high percentage of body fat have a much lower risk of disease if they’re physically fit.
Physical fitness doesn’t necessarily mean trim and toned. It’s a measure of your body’s ability to take up oxygen; in other words how long you can perform an aerobic exercise. The more oxygen your body uses during a single bout of exercise, the harder you’re working, and the more physically fit you are.
If you can lose weight while you exercise, all the better, but “physical fitness is the strongest determinant of overall health,” said Dr. Goodyear. So get up, get out, and get moving!