Scientists at the University of Iowa have discovered an exercise hormone that boosts muscles´ energy production and exercise tolerance.
The study, published in the Proceedings of the National Academy of Sciences Early Edition, shows that exercise causes muscle to release a peptide that improves energy production and physical endurance.
According to the university, the findings establish that the peptide, called musclin, is an “exercise factor” — a hormone-like substance made by skeletal muscle in response to exercise and released into the bloodstream.
The researchers used genetic engineering to create mice that don´t produce musclin. These animals had lower exercise tolerance and were not able to exercise as long or as hard as mice in the control group. However, infusing the musclin peptide back into these modified mice allowed the animals to regain normal exercise capacity in just one week.
Increased levels of musclin in the body trigger a response that improves muscle performance and promotes production of mitochondria in muscle cells, the researchers found.
The study also revealed that infusing normal lab mice with musclin increased the animals´ voluntary treadmill activity; the mice ran faster and longer on the treadmill than those that received a placebo infusion of saline.
“Exercise is an extremely powerful way to improve people´s health, but unfortunately, increasing physical activity can be really difficult in many circumstances,” said senior author Dr. Leonid Zingman, associate professor of internal medicine at the University of Iowa Carver College of Medicine and a physician scientist at the Iowa City Veterans Affairs Medical Center. “We don´t want to replace exercise by using this exercise factor, but if we can learn more about the mechanism, it might help us to increase exercise tolerance and make it easier for people to actually exercise. And if it is easier, people may exercise more.”