CONSERVATION OF ENERGY IN COMPETITIVE SWIMMING

Energy conservation in swimming is formulated in terms of four functio ns of the swim speed v: the consumed power K, the mechanical power P u sed for horizontal propulsion, the remaining expended mechanical power N, and the thermal power loss H. K is well-known (from V-O2) and P = F(D)v, where the drag force F-D is not known with certainty but repres ents a small effect. Estimates of the nonpropulsive components of a sw immer's body motions reveal that N is small,less than 3 watts per kg o f body mass. H is estimated by using the theory of convective heat tra nsfer to express the heat loss in terms of the difference between the swimmer's skin temperature and the water temperature. This temperature difference was measured for the NYU men's swim team and found to be 0 .033 K per kg of body mass, giving H approximate to 34 W kg(-1). The r esults are seen to be in good agreement with the asymptotic (large swi m time t(f)) form of energy conservation. The further requirement that energy conservation is valid to order 1/t(f), and use of the 1993 wor ld record race times, is shown to imply that the initial energy availa ble in a swimmer's body is 963 +/- 231 joules per kg of body mass.