Marathon Organizers Adjust to Rising Temperatures

The increasing temperatures pose challenges for marathon runners, with Paul Grinvalds from West Des Moines, Iowa, being no exception. Despite completing 114 marathons across all 50 states, he struggles to perform in temperatures exceeding 60 degrees Fahrenheit (15.5 Celsius). The difficulty arises because the human body finds it harder to cool down during exercise, especially in warm conditions.

Grinvalds, aged 68, said, “One thing about marathoners is typically we’re kind of stubborn.” He finds temperatures in the 50 degrees Fahrenheit (10 Celsius) range somewhat warm, yet many runners persist with their goals despite the discomfort, risking painful experiences.

Such conditions can be dangerous and have prompted marathon organizers to take measures in light of climate change, primarily driven by the burning of fossil fuels like coal and gasoline, which elevates temperatures. They are altering race dates, starting earlier, and offering runners the chance to shorten their race distances.

Adapting to the Climate

Starting in 2027, the Twin Cities Marathon in Minneapolis-St. Paul will change its over 40-year-old tradition, switching the race from the first Sunday in October to later in the month. This decision followed the cancellation of the 2023 marathon due to record heat and humidity, and starting temperatures at the 2025 race reached near 70 degrees Fahrenheit (21 Celsius).

Similarly, organizers of the Sioux Falls, South Dakota marathon moved their yearly event from August to September after canceling the 2024 race due to hot conditions. The Air Force Marathon in Dayton, Ohio, the Little Rock Marathon in Arkansas, and the Long Beach Marathon in Southern California all adjusted their start times to earlier in the morning to find cooler temperatures.

During the Los Angeles Marathon in March, warm conditions led organizers to give runners an option to complete a shorter distance of 18 miles while still receiving a finisher’s medal. Less than 5% chose the shorter finish, and only 14 out of around 27,000 participants required hospital treatment, with all discharged the same day. The decision provoked online criticism, yet marathon spokeswoman Meg Treat stated, “We welcome the feedback… but when we’re grading ourselves on it, it has to do with how safe our runners were on the day of the event, and we’re very happy with the outcome.”

Analysis and Data Impacting Decisions

The Twin Cities Marathon’s 2023 cancellation, labeled “devastating” by race director Ed Whetham, led to a thorough analysis of weather patterns that culminated in permanently delaying the race by several weeks. This analysis demonstrates that holding the event later in October increases the likelihood of favorable conditions. Although late October can bring snow to the Twin Cities, Whetham commented, “We’ll take a 39-degree start over a 70-degree start.”

Temperatures continue to rise. The United States had its warmest July on record, and 2024 was Earth’s hottest year recorded. Projections from the World Meteorological Organization suggest the planet’s average temperature could climb by more than 1.5 degrees Celsius (2.7 degrees Fahrenheit) above levels from the 1800s between 2025 and 2030. A study by Climate Central found the rising temperatures could worsen marathon conditions, noting that optimal temperatures for recreational running, ideally in the low 40s Fahrenheit (6 or 7 degrees Celsius), could become scarcer in 46 of the 51 analyzed U.S. marathons by 2045.

Climate researcher Andy Pershing highlighted, “The ability to go outside, to exercise, to take advantage of your human body and being healthy, that’s something that’s getting challenged by climate change.”

Broad Impacts on Sports and Exercise

Jessica Murfree from the University of North Carolina-Chapel Hill addresses the effects of climate on sports in her lab. She said organizers of events such as marathons, cycling races, tennis, and college football must increasingly consider adjusting dates and times to account for warmer conditions, as climate change leads to heightened temperatures and volatile weather.

Murfree also believes the concern extends from organized sports to everyday activities. She questions if exercise can remain feasible in high temperatures, often pushing individuals to work out indoors or select cooler activities like swimming. “If we can’t walk, if we can’t exercise or go for runs, it’s too hot, can we still stay physically active while remaining cool?”

Difficulties of Running in Warm Weather

Running a marathon in hot and humid weather can be particularly challenging because preventing overheating is hard when pushing oneself for long periods. The faster a runner’s pace, the more heat the body generates.

According to Chris Minson from the University of Oregon, the ideal temperature for running a marathon is about 50 degrees Fahrenheit (10 Celsius). As the temperature rises into the upper 50s and 60s, the body’s ability to supply blood to muscles while simultaneously cooling itself diminishes.

“As you get to warmer temperatures you end up having a bigger competition between blood supplying your muscles to keep running, to keep nutrition going, and blood flow to your skin for thermal regulation,” Minson explains.

The energy expenditure required to run quickly is immense, as only about 25% is used for forward movement, with the remainder managing the heat produced from fast pacing. High humidity worsens conditions by hindering sweat evaporation and cooling.

Despite these challenges, Minson notes that individuals can adapt to high temperatures through regular exercise in warm weather, often performing better in such conditions. Those acclimated to the heat can also excel in lower temperatures compared to individuals who haven’t exercised in warm climates.

Training Amid Warm Conditions

Some athletes, like John Seals, proceed with midday heat runs and post-exercise sauna sessions for acclimation. Seals, from West Des Moines, includes these practices in his training for an annual 135-mile ultramarathon in July through Death Valley, California. “We had a heat wave this week and for me, that’s a great thing,” Seals said.

Running in heat, however, requires caution. Douglas Casa, kinesiology professor and head of the Korey Stringer Institute, which studies sudden deaths in sports, commended the Twin Cities Marathon’s decision as wise, considering the determination often seen in runners.

“If someone was smart enough to say, ‘OK, it’s a little hotter today than usual, I’m going to run a 7-minute mile instead of a 6:30-mile,’ then they won’t get any hotter than normal,” Casa explained. “It’s just that runners are sometimes very locked into what they normally do and what their goals are.”

Marathons showcase the determination of runners like Paul Grinvalds from West Des Moines, Iowa, who continues training regardless of the conditions. The sport is adjusting as climate change impacts how and when events occur, ensuring participant safety stays at the forefront.

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