The biology of bat wings can serve as lessons for cold weather work, exercise

A new study reveals that the bats' wing muscles function at a much lower temperature than their bodies, especially during flight.

Previous research suggests that in most other creatures, including humans, the muscles involved in exercise become warmer in response to movement. But the small muscles of the wing of a bat are particularly vulnerable to heat loss in flight because they are covered only with a thin layer of skin. Warming would therefore be inefficient from the point of view of energy consumption.

"We tend to assume that warm-blooded animals are hot all the time," said the doctorate of Brown University. Andrea Rummel, student, who wrote the study alongside biologists Brown, Sharon Swartz and Richard Marsh. "But this research shows that the body temperature of warm-blooded animals varies much more than expected, which has implications for the way animals move, including humans."

The results, published in Biology Letters Wednesday, September 11, provides the context for a previous study by the team that the muscles of bat wings are much less sensitive to cold than those of a typical mammal. When muscles cool down, they contract and relax more slowly, so that they do not work as well. This is also true for bats, but to a much lesser extent. Even though their wing muscles cool during the flight, they successfully maintain the fast, fast, coordinated muscular contractions they need to remain suspended in the air.

"We know that bats are able to withstand high-performance locomotion with very cold muscles," said Rummel. "The fact that their muscles are cold indicates that there are probably other small mammals and small birds that also move very well with cold muscles – and they probably all have some muscle adaptation, a behavioral adaptation or another physiological adaptation that helps them do it. "

Understanding any of these mechanisms could help scientists improve the regulation of human exercise through cold or even heat, she added. "We do not know a lot about how to optimize physical performance and protect people safely during intense exercise and in extreme conditions," Rummel said.

Marsh said the group's work could also improve the understanding of muscle performance for people in certain professions.

"Especially for workers like fishermen, who work in cold waters, and for other people who have to do outdoor work, there are problems with the small muscles of the hand and the front. arm, "he said. "It is therefore interesting to quantify these aspects and determine the effects of cold on the muscles."

To conduct their research, the team used temperature sensors inserted into the wings of bats. Eventually, they found that the muscles of the biceps and forearms were significantly colder than the muscles of the central body, and this temperature difference became even more pronounced immediately after the start of the flight of the bats. especially in the muscles of the forearm, which were about 12 degrees colder than the nucleus. During the flight.

Now that they have confirmed that bat wing muscles operate at extremely low temperatures and seem less vulnerable to cold-related performance deficits, researchers will be working to explore the intrinsic properties of muscles. Specifically, they will take a closer look at a protein called myosin, an essential building block of muscle. Myosin is present in both bat muscle and human muscle, but genetic or environmental factors may have influenced myosin in bat wings for it to develop reduced susceptibility to cold.

The researchers also plan to use electromyography to evaluate the activation patterns of the wing muscles when the bats are flying.

"One of the possible mechanisms for dealing with the cold," said Marsh, "is simply to activate more muscle, so if your muscles tend to slow down, you can compensate to a certain extent by further activating the muscle. muscle volume. " a possible mechanism that we hope to examine in bats. "