Question 21 LB01 - Lifeboat Operator

The Correct Answer is A. **Explanation for A (It will increase the rate of heat loss from the body):** Physical exertion (swimming, treading water, struggling) requires the movement of muscles, which in turn necessitates increased blood flow to those muscles. This warm blood is brought closer to the skin surface (peripheral circulation) and to the limbs, where the heat is rapidly conducted away by the surrounding cold water. Furthermore, movement disrupts the thin, stationary layer of water warmed slightly by the body (the boundary layer) or flushes out any warmed water trapped within clothing. By constantly replacing this boundary layer with fresh, cold water, the temperature gradient between the body and the water remains high, dramatically accelerating the rate of conductive and convective heat loss, leading to hypothermia much faster. **Why the other options are incorrect:** * **B) It will increase the water temperature between the body and layers of clothing:** This is incorrect. While the body does produce heat, physical exertion causes movement (convection), which actively pumps the warmer water out of the clothing layers and replaces it with cold water from the outside environment, thus decreasing the insulation provided by the clothing and flushing the warmed water away. * **C) It will increase survival time in the water:** This is incorrect. Because exertion dramatically increases the rate of core body temperature drop (accelerated heat loss), it significantly reduces the time until incapacitation and death from severe hypothermia. The standard advice in cold water is to remain still (H.E.L.P. position) to conserve energy and heat. * **D) It will decrease exposure of the body surface to cold water:** This is incorrect. Exertion does not reduce the surface area exposed; in fact, struggling often requires the limbs to be extended and moved, which maximizes the skin surface area subjected to cold water convection.