Energetics of swimming: A historical perspective

The energy cost to swim a unit distance (C _sw) is given by the ratio Ė/ν where Ė is the net metabolic power and v is the swimming speed. The contribution of the aerobic and anaerobic energy sources to Ė in swimming competitions is independent of swimming style, gender or skill and depends essentially upon the duration of the exercise. C _sw is essentially determined by the hydrodynamic resistance (W _d): the higher W _d the higher C _sw; and by the propelling efficiency (η _P): the higher η _P the lower C _sw. Hence, all factors influencing W _d and/or η _P result in proportional changes in C _sw. Maximal metabolic power (Ė_max ) and C _sw are the main determinants of swimming performance; an improvement in a subject's best performance time can more easily be obtained by a reduction of C _sw rather than by an (equal) increase in Ė_max (in either of its components, aerobic or anaerobic). These sentences, which constitute a significant contribution to today's knowledge about swimming energetics, are based on the studies that Professor Pietro Enrico di Prampero and his co-workers carried out since the 1970s. This paper is devoted to examine how this body of work helped to improve our understanding of this fascinating mode of locomotion.