ABSTRACT
Open-water swimming (OWS) is an outdoor endurance discipline that takes place in oceans, seas, rivers and lakes. OWS involves physiological issues and environmental challenges not typically seen in other events within aquatic sports. However, performance in OWS is determined/affected by the specific challenges of aquatic locomotion; this chapter will thus be introduced by general principles regarding the bioenergetics and biomechanics of swimming with a specific focus on the physiological and biomechanical determinants of endurance speed. When compared to other endurance disciplines, in conventional OWS races sex differences in performance are rather low. Pacing strategies in OWS depend, among other factors, on the benefits of drafting. OWS is in fact a head-to-head competition where finishing position rather than finishing time is important and where the differences between the winner and the other competitors may be only marginal. A common risk in OWS is hypothermia; according to the American Heart Association hypothermia is defined as a core body temperature below 35°C.
