Brief report of core temperature patterns in triathletes while swimming in warm open water with and without a wetsuit

This exploratory study investigated the effects of wetsuit use on core temperature patterns in triathletes in warm open water swimming (27.9-28.3°C).

Participants (males (2), females (2), 49.5±7.8 years, body fat 16.3±5.56%) completed two 700-meter open water swims at self-selected submaximal paces: 1) wearing a full sleeve wetsuit (WS) and 2) no wetsuit (NWS). Core temperature was measured using an ingestible temperature pill (sample rate: 15-seconds). To explore the core temperature vs. time patterns, each data set was fit with a 1^st, 2^nd, and 3^rd order polynomial. The sum of residuals squared was calculated to evaluate the goodness of the fit of each line. As a descriptive study, patterns of core temperature changes were qualitatively determined.

Swim performance was faster in the WS condition (742.5±148.2 s) vs. NWS condition (907.5±246.6 s) (p=0.02). For core temperature vs. time patterns, of the 8 data sets (i.e., four participants, two conditions), there was general improvement with the line of best fit in at least 5 data sets using the 2^nd vs. 1^st order polynomial and no appreciable improvement using a 3^rd order polynomial. Interestingly, there was no improvement of fitting the data using higher order polynomials for two participants - both during NWS. However, there was improvement of fit using at least a 2^nd order polynomial for all participants during WS.

Overall, inspection of the residuals seems to indicate that the linear or nonlinear rate of change of core temperature is individualized. Furthermore, there was no risk of hyperthermia in either condition.