History and Risks of Marathons and Triathlons
Marathons and triathlons have steadily garnered attention since their inception in the 1980s. Despite the general fitness and health of their participants, sudden death is a reality for 0.5-1.7 athletes per 100,000 participants, as reported by previous studies. Most fatalities in triathlons occur during the swimming phase, often linked to cardiovascular disease. The mortality rates highlight the need for safety measures and risk reduction, especially against hypothermia during swimming.
The Threat of Hypothermia in Open Water Swimming
Cold water immersion can result in hypothermia, typically identified by an internal body temperature below 35 °C. Swimming induces an intricate interplay between metabolic heat production and heat loss into the water, impacting the body’s internal temperature. Maintaining awareness of such risks is crucial in all activities associated with open water swimming.
The Emergence of Extreme Triathlons
The Norseman Xtreme Triathlon, first held in 2003, sparked a new trend in the triathlon world. This extreme event includes a 3,800-meter swim in the Hardanger Fjord, a 180 km bike stage, and a 42.2 km run ending at Mount Gaustatappen. The popularity of such competitions has grown over the years, with XTRI-World organizing 17 extreme triathlons worldwide since 2012.
Facing Cold Weather Conditions in Triathlons
Some of these extreme triathlons, like the Swedman and Celtman events, take place under cold weather conditions, making the swim stage a chilling challenge. Despite being a summer event, the Norseman often encounters low water and air temperatures. This has led to safety-based decisions like shortening the swim length in 2015, highlighting the lack of data on hypothermia risks during such races.
Studying the Impact of Cold Water Swims on Athletes
This study aims to evaluate the incidence of hypothermia during a full triathlon swim in cold water, using internal temperature measurements from the 2017, 2018, and 2019 races. The study also assessed the potential effects of cold water swimming during the first hour of the cycling stage.
Hypothermia Risk Assessment in Full-Distance Triathlons
The study included 51 participants, each of whom had their internal temperature monitored using a swallowed capsule. Despite all subjects wearing wetsuits in water temperatures of 14.4-16.4 °C, one athlete with a low body mass index experienced hypothermia. The findings indicated no relationship between body temperature and factors like swimming time, BMI, or gender.
Concluding Insights from the Study
The study concluded that athletes with low BMI and long swimming times might be at risk of hypothermia during full-distance triathlon swimming, even when wearing wetsuits, at water temperatures of about 15-16°C.