{"id":28073,"date":"2026-11-11T09:00:00","date_gmt":"2026-11-11T08:00:00","guid":{"rendered":"https:\/\/dixsupps.com\/running-in-the-heat-why-the-body-gives-up-and-what-studies-say\/"},"modified":"2026-11-11T09:00:08","modified_gmt":"2026-11-11T08:00:08","slug":"running-in-the-heat","status":"publish","type":"post","link":"https:\/\/dixsupps.com\/en\/running-in-the-heat\/","title":{"rendered":"Running in the heat: why the body gives out, and what the studies say"},"content":{"rendered":"\n

A long run in July, 30\u00b0C in the shade, not a breath of wind, and your legs respond a little less with every kilometre. You can still run in the heat, and most runners get away with nothing worse than a tough session. When the body really gives out, several things can combine: rising temperature, the brain easing off the throttle, sugar or sodium dropping.<\/strong> A lack of salt, the explanation you hear everywhere, is rarely the main cause.<\/p>\n\n\n\n

To the naked eye, these mechanisms look alike. But you don’t prepare for them the same way, and they don’t call for the same response at the roadside. Here’s what the studies show, what they leave open, and what you can take away for your summer running.<\/p>\n\n\n

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The short answer<\/p>\n

To run in the heat, slow down, acclimatise over one to two weeks, eat and drink what you’ve tested in training, and cool yourself without relying only on how you feel. When a runner collapses, four causes are on the table: heat, low sodium, low blood sugar and a drop in blood pressure. Only measurements can settle it. Anyone who is confused or staggering should stop, and emergency services should be called.<\/p>\n<\/div>\n <\/div>\n <\/div>\n \n\n\n\n

The case that reignited the debate<\/h2>\n\n\n\n

On 10 October 2026, at the Ironman World Championship in Kona, Hawaii, defending champion Solveig L\u00f8vseth was leading just over a kilometre from the finish when she staggered and fell several times. She lay down for a few minutes, then walked to the line in eighth place. She’s fine. That day, 22 of the 77 professionals dropped out. [36]<\/a><\/p>\n\n\n\n

She talked about a probable form of overheating, and her team about a shortage of food and salts. [37]<\/a> [35]<\/a> No temperature, sodium level or blood sugar reading has been published. Without those three numbers, nobody knows what happened, and this article won’t try to guess. What follows is about runners in general, and what sports doctors check when one of them goes down.<\/p>\n\n\n\n

One detail concerns you directly: this wasn’t extreme weather. The Kona airport station recorded 30.6\u00b0C and 63% humidity at 2.53pm, a feels-like temperature of 34.7\u00b0C. [38]<\/a> The 85% humidity quoted in the press was the morning figure. The airport is by the sea and the road was probably a little hotter, but these are conditions you could meet at a summer race in southern Europe, or during a British heatwave.<\/p>\n\n\n\n