Safe cold-water thresholds while wearing wetsuits approved for open water swimming competitions

Area of Science:

• Sports Science
• Environmental Physiology

Background:

• Open water swimming competitions often have minimum temperature regulations for participant safety.
• The critical cold-water temperature (T_crit) is the lowest temperature at which core body temperature can be maintained.
• Current regulations mandate a minimum water temperature of 16°C for wetsuit-approved events.

Purpose of the Study:

• To test if the T_crit for trained swimmers in wetsuits is below the 16°C regulation.
• To investigate the impact of wetsuit sleeve design (sleeved vs. sleeveless) on T_crit.
• To identify physiological factors influencing T_crit in cold-water swimming.

Main Methods:

• Twenty trained swimmers (12 men, 8 women) underwent 120-minute progressive cooling swim trials in a swim flume.
• Water temperature decreased from 16°C, simulating race conditions at a representative intensity.
• T_crit was determined using segmental linear regression; a subset compared wetsuit types.

Main Results:

• The median T_crit was 15.0°C, significantly lower than the 16°C regulation (p<0.001).
• No significant differences in T_crit were found between genders or between sleeved and sleeveless wetsuits.
• Body fat percentage, metabolic heat production, and body surface area-to-mass ratio were significant predictors of T_crit (R²=0.41).

Conclusions:

• Trained swimmers in wetsuits can tolerate water temperatures below the current 16°C mandate.
• Despite physiological tolerance, maintaining the 16°C regulation is recommended for safety margins.
• Variable real-world conditions and diverse athlete populations necessitate conservative temperature guidelines in open water swimming.