Triathlons as well as long distance endurance swims are popular events [1], [2]. During these events, environmental conditions such as water temperature may influence swim performance [1], [2], [3], [4]. Thermoregulation is crucial for both hypothermia and hyperthermia as both conditions may be detrimental to athletes during a race [1], [3], [5].

There has been a focus of research on the influence of wearing a wetsuit on core temperature when swimming in cold water [[1], [2]]; however, less is known about how a wetsuit may influence core temperature when swimming in warmer water. Some initial work by Trappe et al. (1995) investigated the thermal responses in while swimming in 25.6 °C water with and without a wetsuit and reported an increase in core temperature of 0.89 ± 0.13 °C and 1.22 ± 0.24 °C, respectively [4]. However, there is currently no research on how core temperature varies over time while swimming in a triathlon wetsuit in warm water.

Therefore, the purpose of this study was to investigate whether or not core temperature was influenced by wearing a wetsuit during a warm water swim (25.5 °C) vs. not wearing a wetsuit. More specifically, the purpose of the study was to compare core temperature while wearing a wetsuit during a 1000 m swim in warm water (25.5 °C) to core temperature while not wearing a wetsuit over the same distance and to describe core temperature during the course of the 1000 m swim. It was hypothesized that core temperature would be greater when wearing a wetsuit than without a wetsuit while swimming in warm water (25.5 °C).