A 26-year-old Fijian rugby player, Saimoni Vunilagi, collapsed during a training session with his team at Japan's Kyuden Voltex club and later died from symptoms consistent with severe heatstroke, according to a statement from the club. The incident occurred in Fukuoka, where temperatures had reached 35°C with humidity over 75%. This followed a period of consistently high temperatures, with daily highs ranging between 32 and 37°C in the weeks leading up to the event. Vunilagi's death has sparked concerns about the risks of extreme heat to athletes, especially as global temperatures continue to rise. Heat-related incidents have become more frequent in recent years, with similar cases reported in 2026, including collapses during tennis matches and a marathon in South Korea. Cyclist Tadej Pogacar described the heat during the Tour de France as "dangerous," and Matthew Brennan raised concerns about the conditions during the Vuelta a Espana, where temperatures exceeded 40°C. These incidents highlight the growing challenges athletes face due to increasingly extreme weather conditions. Sports organizations use the Wet Bulb Globe Temperature (WBGT) index to monitor heat stress levels and determine safe conditions for training and competition. However, experts warn that the number of heat-related illnesses in sports has increased in recent years, and current heatwaves are hotter than those experienced in the past. Dr. Madeleine Orr, an assistant professor of sport ecology at the University of Toronto, emphasized that previous heat conditions may no longer be considered safe, as today's heatwaves are more intense than those of previous decades. She called for standardized policies to address heat risks in all sports, similar to those used for lightning safety. Christian Day, general secretary of the Rugby Players' Association, noted that it is challenging to convince athletes and coaches to prioritize health over performance. He advocated for clear regulatory thresholds for heat stress to ensure immediate action when conditions become dangerous. World Rugby updated its heat and air-quality guidelines in 2025, including a heat stress index and provisions for water breaks and extended half-time periods. However, the majority of athletes' time is spent training rather than playing matches, and current guidelines may not fully address the risks during training sessions. The Japan Rugby Football Union (JRFU) warned in June 2026 that heatstroke is an increasing concern during the summer, urging clubs to prioritize safety in planning summer training camps. Heatstroke is a preventable condition that can be fatal within an hour if not treated promptly. Symptoms include dizziness, nausea, headache, confusion, and slurred speech. Orr stated that every death from heatstroke is preventable and that professional athletes, despite their fitness, are not immune to its dangers. She also noted that larger athletes are more vulnerable due to the increased energy required to move their mass. Both elite and amateur athletes are at risk, with the latter potentially influenced by the behavior of professional athletes.