Working out could help us fight off colds and other infections, according to a timely new study. The study, which found that regular exercise strengthens the body’s immune system in part by repeatedly stressing it, was conducted in animals. But the results most likely apply to people, the researchers say, and could offer further incentive for us to remain physically active this winter.

In broad terms, our immune system reacts to invading microbes through a variety of cells. Some of these cells don’t directly combat the infection, but instead promote the development of inflammation. When we think of inflammation, we usually think of fever, swelling and redness. But inflammation can also be a good thing, helping the body to heal itself as it fights invading microbes.

The problem is that inflammation can easily get out of hand. If the inflammatory response to an infection or injury is too robust or indiscriminate, the inflammation can ultimately cause more tissue damage and lingering health problems than it prevents.

Scientists have long tried to determine why inflammation sometimes grows rampant in the body. One thing they’ve noticed is that fat cells are particularly adept at producing substances that promote inflammation, in part as a response to messages from the immune system.