Manchester United is employing cooling jackets to aid their players in managing the heat during their Premier League Super Series campaign in the United States.
Cooling jackets have existed in various forms since the 1950s and 60s, initially used by the military. Over time, they have been adopted in numerous sports, including Formula 1, cycling, tennis, and rowing.
These jackets are designed to lower an athlete's core and skin temperature, with studies indicating they can enhance endurance and performance while mitigating the risks of heat stroke and heat exhaustion.
The version currently used by Manchester United is part of a range by Adidas, launched earlier this year.
Players are wearing these cooling jackets after warm-ups and during halftime of their three matches in the United States.
During the 2025 Club World Cup this summer, players faced extreme heat in several matches, necessitating multiple cooling breaks and the installation of large mist fans on the sidelines in some stadiums.
Borussia Dortmund's substitutes spent the first half of their group stage match against Mamelodi Sundowns in the changing room to avoid the heat.
How are cooling jackets used and do they actually work?
The earliest cooling jackets used by the military required a power supply to circulate cold water around the body. However, technological advancements have eliminated this need.
Adidas' Climacool System, released earlier this year, includes an insulated jacket worn over a cooling vest.
Dr. Chris Tyler, a reader in environmental physiology at the University of Roehampton, explains, "For the same exercise intensity in hot conditions compared to cooler ones, the heart rate and body temperature are higher, increasing the risk of heat stroke and heat exhaustion."
"The vest aims to reduce these effects by lowering body temperature, heart rate, and strain," he added.
The vest's effectiveness depends on its sustained use and coverage of the body, allowing the body to cool down more efficiently, reducing heat-related risks and enhancing athletic performance.
A difference maker for the 2026 World Cup?
The conditions during the Club World Cup, seen as a precursor to the 2026 men's World Cup, provide insights into what can be expected during next summer's tournament across the United States, Canada, and Mexico.
With 48 nations participating compared to the 32-team Club World Cup, there will be more daytime matches, posing additional challenges for players in coping with the weather.
Dr. Tyler suggests, "Proactive cooling interventions will be necessary at the Club World Cup."
"The ideal solution is to avoid playing in such conditions, but that's not feasible for many reasons. Alternative scheduling, such as early or late kick-offs, could help," he noted.
He anticipates widespread use of cooling jackets or similar equipment during the World Cup, with teams already preparing for the heat.
"Teams with substantial support will likely adopt these strategies, and all national teams should have access to resources to avoid being disadvantaged," Dr. Tyler emphasized.
Cooling jackets in Formula One
In March, Adidas introduced their Climacool System, comprising an insulated jacket and a specially designed cooling vest.
F1 team Mercedes uses these jackets for races in hot weather conditions that could affect driver performance.
According to the manufacturer, drivers can experience temperatures between 55°C and 60°C, resulting in a weight loss of 4.2 kg (9.3 pounds) from sweat during a single race.
F1 drivers typically immerse themselves in water before a race to cool their bodies in preparation.
Dr. Tyler explained, "Drivers wear the vests primarily for perceptual cooling, aiming to feel cooler for longer."
He added that the FIA plans to introduce in-car cooling suits for hot races, similar to those used by the military, although their effectiveness in reducing driver strain remains uncertain.
Additionally, these vests provide a platform for sponsors to display their logos, which Formula One teams have recognized as an advantage.