Safe Cold-water Temperature Thresholds Do Not Differ Between Sleeved And Sleeveless Wetsuits In Competitive Swimmers

Hypothermia is a concern when hosting open water swimming events. According to World Aquatics, open water events are prohibited when water temperature is less than ~16 °C and requires a wetsuit when ≤18 °C. The wetsuit mandate requires wetsuits cover the torso, back, shoulders and knees. Many athletes prefer sleeveless (SL) options over full-length (FL) wetsuits. However, the effect of wetsuit sleeves on the safe cold-water temperature threshold (termed critical cold-water temperature, Tcrit) is unknown. PURPOSE: To determine whether Tcrit differs between sleeveless and full-length wetsuits. METHODS: Seven competitive swimmers (5 women) completed two swims that lasted up to 120 minutes in water starting at ~16 °C and progressively decreasing to ~13 °C. One swim was completed in a FL wetsuit and one in a SL wetsuit, with the order assigned in a block randomized manner. Both wetsuits were from the same manufacturer, World Aquatics approved and 3 mm thick. The workload during each swim was the same as that observed during a 3 km self-paced swim as determined by heart rate. Rectal (Tc) and skin temperature (10 sites, unweighted, Tskin) were measured continuously. Every 30-minutes oxygen uptake and RER were measured via indirect calorimetry, which was used to estimate the rate of metabolic heat production (Hprod). Tcrit was determined as the water temperature at which Tc began to decrease, as determined by segmental regression. Tskin and Hprod data were analyzed during the first 30 min (initial) and last 30 min (final) of the trial. Data are presented as mean ± SD. RESULTS: Tcrit did not differ between SL (15.3 ± 0.5 °C) and FL (15.2 ± 0.5 °C, p = 0.7869). Initial Tskin (SL: 21.6 ± 0.9 °C; FL: 3.0 ± 1.8 °C; p = 0.0751) nor initial Hprod (SL: 849 ± 108 W; FL: 827 ± 139 W; p = 0.2538) differed between trials. While final Tskin did not differ (SL: 21.0 ± 1.0 °C; FL: 21.7 ± 2.0 °C; p = 0.2462), final Hprod was higher during the SL trial (848 ± 114 W vs. 816 ± 120 W, p = 0.0054). CONCLUSION: The safe cold-water temperature threshold does not differ when wearing a sleeveless vs. full-length wetsuit. However, Hprod was higher at the end of the sleeveless trial, which may offset higher heat loss from the arms. Support: World Aquatics Supported by: World Aquatics