Overheating is a problem for many athletes, but wheelchair athletes can face an even more extreme version of this challenge. Many of these athletes compete with spinal cord injuries and therefore “are unable to sweat and control their blood flow below the level of their lesion,” said Katy Griggs, who researches the thermoregulatory responses of wheelchair athletes. The ways that these Paralympians “can cool themselves by external sources are important,” she told Ars.

Due to these difficulties with thermal regulation, Team USA wheelchair rugby players (all but two of whom have spinal cord injuries) jokingly refer to themselves as “reptiles.” But their efforts to cool themselves during the 2016 Paralympic Games, beginning this week in Rio de Janeiro, are deadly serious.

Trainers generally pay close attention to athlete temperatures and the possibility of heat illness, but they have to be extra vigilant when it comes to wheelchair athletes because self-monitoring can be more difficult. For instance, wheelchair users can’t always see the color and amount of their own urine, making it more difficult to use it as a gauge to hydration. (And to be more alert to dehydration or overhydration, Team USA staff now use refractometers to measure the gravity in urine.)