The prevalence of exertional heat illness may be greater in those who undertake sports events like the triathlon. Participants of the ultra-endurance Ironman triathlon may utilize as much as 10 thousand kilocalories in the 8–17 h of activity, 75% of which is converted to heat.
Those who train for prolonged periods in physiologically challenging environmental conditions are especially vulnerable and more so if they are not adequately hydrated.