What if I told you that these cooling shirts actually make things WORSE for drivers… and they’re mandated for 2026 💀
TL;DR: Mercedes-AMG FUNDED a peer-reviewed study on F1 driver cooling tech and found the “Cool Shirt” actually leaves drivers HOTTER than wearing no cooling at all (38.58°C vs 38.32°C after 60 mins in heat).
which sounds contradictory right? cooling the skin actually tricks your hypothalamus into thinking you’re fine, so it shuts down your body’s NATURAL cooling response (sweating, vasodilation)—trapping heat inside instead. And the garment’s own cooling capacity craps out after ~30 minutes anyway, way short of a 90-120 min race.
Drivers wearing it FELT cooler and pushed through longer, even while their actual physiological strain was higher. Meaning the shirt masks real overheating risk rather than preventing it.
And apparently the thing that actually worked best in testing (a suit blower) isn’t even commercially available or FIA-approved anymore.
McKnight, P.J., & McKnight, J.T. (2026). “My engine is overheating!”: Cooling strategies for Formula 1 drivers. Sports Science Exchange, #271. https://www.gssiweb.org/en/sports-science-exchange/article/my-engine-is-overheating!---cooling-strategies-for-formula-1-drivers
Once the race begins, options for managing thermal strain are extremely limited by safety regulations. FIA sporting rules prohibit the addition of fans or any active cooling devices to the car, and no external cooling intervention is permitted once the race is underway. Two tools remain: the pre-fitted water-circulating liquid-cooling garment worn under the suit, and fluid ingestion. The cooling system, often referred to colloquially as a “Cool Shirt,” is a water-perfused undergarment covering the torso (chest, back and upper arms). The legs are not perfused, although designs continue to evolve. From the 2025 season the water-circulating cooling garment is mandated when the race is declared a “heat hazard” (forecast ambient temperature ≥31°C). From 2026, the liquid-cooling garment must be fitted to and worn by every driver at every event, irrespective of forecast temperature, although activation remains at the driver’s discretion (Tyler et al., 2026).
The mandated “Cool Shirt” raises important questions. The first peer-reviewed controlled comparison of driver cooling technologies, funded by the Mercedes-AMG Petronas Formula 1 Team, produced a counterintuitive finding. The Cool Shirt not only failed to reduce core temperature relative to a no-cooling control, but it was also associated with a higher core temperature (38.58 vs. 38.32°C) following 60 min of exercise at 32°C and 80% humidity in full FIA-specification attire (Davis et al., 2026). A suit-blower device produced the lowest core temperature (37.51°C), though it is not currently sanctioned for Formula 1 use. The Cool Shirt did attenuate skin temperature, but its apparent exacerbation of core heat load relative to no cooling raises important questions about its adequacy as the sole mandated intervention. The mechanism behind this paradoxical finding is likely a thermoregulatory negative-feedback effect. Cooling of cutaneous thermoreceptors signals the preoptic area of the hypothalamus to reduce heat-loss responses (cutaneous vasodilation and sweating), thereby trapping endogenous metabolic heat in the core (Ishizuka et al., 2025). Davis et al. (2026) further noted that participants reported the garment “warming up” after ~30 min, suggesting cooling capacity declines as the chiller’s reservoir is overwhelmed by the heat load. The combination of attenuated endogenous cooling and waning device cooling plausibly explains the higher final core temperature observed in the Cool Shirt condition.
Three further findings from Davis et al. (2026) warrant attention for Formula 1 teams. First, the Cool Shirt’s effectiveness waned after ~30 min, a meaningful limitation for 90–120 min races. Second, despite producing the highest core temperature and physiological strain values, more participants completed the Cool Shirt condition than no-cooling, indicating that cooling sensation can mask physiological deterioration and in a racing car, this dissociation carries a real safety risk. Third, system failure has been observed in ~15% of motorsport events over 15 years of field research although this applies primarily to the Rini system used in the North American series. Formula 1 teams use bespoke garments with potentially different reliability, but rigorous pre-event system checks are essential. Teams should treat the mandated Cool Shirt as a regulatory minimum and invest in optimizing coolant temperature and flow rate while layering with pre-race strategies.
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