Polar bears can run as fast as 40 kilometers per hour—but only for short distances. Younger, leaner bears are the best runners and are able to cover two kilometers without stopping. Older and larger bears, on the other hand, quickly overheat. This overheating phenomenon is very common in polar bears, as they expend more than twice the energy of most other mammals when walking or running—showing higher than average increases in temperature and oxygen consumption.
