‘Hot Running’ Helps Athletes Tolerate Heat and May Translate into Pace Gains

Practical heat acclimation protocol can prepare runners to perform in hotter conditions

Minneapolis-A three-week heat acclimation intervention helped female athletes better tolerate heat and may be helpful for maintaining an unfatigued "race pace," known as durability. Although the findings fell short of the study's main goal of showing statistically significant improvements in durability, researchers say the study offers a useful protocol for heat adaptation that is practical to implement as a complement to standard training. Researchers will present their work this week at the 2026 American Physiology Summit in Minneapolis. The Summit is the flagship annual meeting of the American Physiological Society (APS).

"The heating protocol we used appeared to elicit meaningful adaptations for heat preparedness, while modest or equivocal changes were observed in our metric of durability. This heat protocol was designed specifically for athletes to maintain normal training while undergoing the intervention and may be useful for implementation at many levels of sport," said the study's first author Katie Lucernoni, MS, a PhD candidate at the University of Oregon.

Durability is an emerging area of focus for athletic performance. To measure durability, researchers compare an athlete's performance (such as race pace, or the highest steady state an athlete can maintain during running) in an ideal or rested state versus their performance after fatiguing exercise. A lower margin of difference means the athlete is more durable or resilient in the face of fatigue.

Previous studies have shown durability improvements with interventions such as strength training, carbohydrate ingestion and the use of "super shoes." In the new work, researchers sought to find out if heat acclimation could bring similar benefits.

The researchers tested their protocol in 23 endurance-trained female runners, with half assigned to a heat protocol and half serving as controls. Each group trained for two 30-minute sessions per week for three weeks. The control group trained in normal conditions, while the heat acclimation group trained in progressively hotter conditions each week: just over 100°F the first week, 104°F the second week and nearly 108°F the third week. The heat acclimation group also spent two additional 30-minute sessions in a hot tub each week at close to 106°F.

All participants underwent durability tests before and after the training. There was a trend toward improved durability in the heat acclimation group compared with controls, although the difference did not reach the threshold for statistical significance. This group also appeared to experience fatigue differently after the heat protocol, suggesting the protocol may still confer meaningful performance-based adaptations. In the heat tolerance tests-a 30-minute run at 100°F-the heat acclimation group had a lower peak core body temperature, lower peak heart rate and increased sweat rate after their three-week training, while the control group showed no such improvements. This demonstrates that the protocol successfully improved athletes' heat tolerance.

Researchers noted that it is possible that a more intensive study protocol may have resulted in more discernable drops in race pace after the heating intervention.

NOTE TO JOURNALISTS: The American Physiology Summit will be held April 23-26, 2026, in Minneapolis. To schedule an interview with the researchers, conference organizers or presenters, or to request the abstract "Heat Acclimation Does Not Improve Running Resilience in Female Athletes," contact APS Media Relations or call 301.634.7314. Find more highlights from the meeting in our Newsroom.

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