What effect does physical exertion have on a person who has fallen into cold water?

When a person falls into cold water, physical exertion occurs as they attempt to swim, stay afloat, or escape the cold environment. This exertion can actually increase the rate of heat loss due to several factors. In cold water, the body's heat dissipates more rapidly than in air. When exerting oneself physically, the body generates a small amount of heat through muscle activity, but this is often insufficient to counteract the significant heat loss to the cold water surrounding them.

When a person is active in cold water, their body increases blood circulation to active muscles, which can lead to a further redistribution of heat from the core to the extremities. As a result, the core body temperature may drop more quickly than it would if the person were motionless. Therefore, the act of exerting itself does not help in maintaining body temperature effectively.

In contrast, maintaining body temperature, aiding in flotation, and delaying the onset of hypothermia are not outcomes associated with physical exertion in cold water. Instead, a more restrained and less vigorous reaction is generally recommended to conserve energy and minimize heat loss.