The latest study finds an intriguing connection between weight-bearing exercises and a lower risk of diabetes.
While lifting weights is more often associated with strengthening muscle and keeping bones healthy, those exercises primarily benefit what’s known as red muscle, which gets its color from mitochondria, the energy factories of cells. Red muscle is the core of endurance athletes’ strength and helps them to power through sustained workouts. But it turns out that another type of muscle, white muscle, which is more prevalent among sprinters, weightlifters and those who use resistance training, where short bursts of energy are critical, may play a role in regulating blood sugar.
White muscle also becomes more prevalent as people age, as the cells start to rely more on glucose for energy. That’s partly why researchers have long believed that the shift from red to white muscle is can be harmful, since the dependence on glucose can encourage insulin resistance. Greater demand for sugar leads to higher levels of the hormone insulin that can overwhelm cells and leave them unable to respond to the sugar-metabolizing hormone, which provides the ideal environment for diabetes. But in the latest research published in the journal Nature Medicine, scientists from the Life Sciences Institute at the University of Michigan question that view, reporting that white muscle may actually keep blood sugar levels in check.
“Despite the good correlation between diabetes and white muscle, the cause and effect relationship has not been proven and remains controversial,” says study author Jiandie Lin, a Life Sciences Institute faculty member and associate professor at the University of Michigan Medical School.
The researchers bred mice to pump out more of a protein — called BAF60c — linked to the development of white muscle. They found that mice with higher levels of BAF60c did in fact have paler muscles, which confirmed that the protein is part of the pathway for their white muscle development.
They then put the mice on treadmills to compare their physical endurance to a group of control mice with less BAF60c. The BAF60c mice were able to run powerfully for short distances, but wore out faster than the other animals. The genetically altered mice were then put on a high-fat diet, and to the researchers’ surprise, the animals exhibited better control over their blood sugar levels than mice on the same diet who weren’t making more of the protein.
“What our study highlights is that having more white muscle per se is not deleterious. When we activate the white muscle program in mice through a transgene, we observed that the mice are protected from fatty diet-induced metabolic disorders. They have a better ability to control blood glucose levels,” says Lin. Previous studies hinted that weight-bearing exercises could benefit diabetes risk, but the latest findings provide a more detailed explanation for why. If further research shows the BAF60c pathway is indeed a safe and effective way of building white muscle and improving blood sugar management, patients may be able to take advantage of activities that can boost white muscle production, such as weight lifting, as well as drugs that can produce the same effect, to control the insulin resistance and high glucose levels that forecast diabetes.