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If you’ve ever found yourself shivering uncontrollably after a race, you’re not alone—the phenomenon is a common occurrence at the finish line of many endurance events, from marathons to Ironman triathlons. Even in sweltering summer temperatures, many athletes find themselves covered in goosebumps and shivering uncontrollably minutes after crossing the finish line.
For some, the symptoms are brief and unremarkable; for others, they’re intense and uncontrollable. It may feel like one’s internal thermostat is busted when this happens, but it’s exactly what your body should be doing, says Dr. Leah Roberts of SteadyMD.
“Our bodies are a complex machine under 24/7 surveillance for keeping homeostasis, or ideal balance of function,” says Dr Roberts. “Through a network of hormones, the body will make every attempt to keep body temperature at its ideal set point of 37-38 degrees Celsius. This is the internal temperature at which intracellular and extracellular enzymes function with highest efficiency and can keep the ‘machine,’ or your body, going.”
While racing, one’s core temperature rises, causing the body to kick in cooling mechanisms almost immediately. Blood vessels closest to the skin dilate to facilitate cooling by sweating and sweat evaporation. When you stop racing, the opposite happens—the body’s core temperature plummets, directing away from the skin and back to the internal organs.
“Whether it’s 50 degrees Fahrenheit or 95, the body’s response to this drop in core temperature is the same,” explains Dr. Roberts. “When the core temperature is less than the ideal 37 C, hormones trigger the body’s shivering response to produce more heat, regardless of how hot it may be outside.”
Uncontrollable shivering, chattering teeth, goosebumps, decreased heart rate, and nausea are common manifestations of the body’s attempt to get back to homeostasis. If the skin or clothing are wet with sweat or the remnants of an aid-station soaking, this can heighten the intensity of the shivers.
To avoid this plummet in body temperatures, Dr. Roberts advises athletes to take the mylar “space blanket” offered at the finish line of most endurance events—even if you don’t feel cold just yet. These thermal blankets help to bring the body’s temperature down gradually, which can reduce (or even eliminate) the post-race shivers.
As soon as possible, athletes should get indoors and change into warm, dry clothing, socks, and shoes. If the shivers continue after changing clothes, consume warm liquids, like tea or soup. Symptoms should subside within a few hours of finishing the race, but if they don’t, or if confusion or vomiting sets in with the shivers, get to a doctor immediately—it could be a sign of something serious.