Sports Science Update: Train Hot/Race Cool?

I called it: heat acclimatization training improves endurance performance in temperate conditions.

Written by: Matt Fitzgerald

On January 7, 2004, I sent the following email message to Timothy Noakes, professor of exercise science at the University of Cape Town, South Africa, with whom I had never previously communicated but long wanted to strike up a correspondence:

Dr. Noakes,

I am an American writer/runner writing a book entitled The Cutting-Edge Runner for Rodale Books. The new edition of your Lore of Running is a proving to be an invaluable resource for this project. But the information presented on thermoregulation raises one question: Is there a potential advantage to runners of training in hot weather for cool-weather racing? That is, will the adaptations they experience offer a performance benefit even in mild conditions, considering that, as you say, 75 percent of the energy a runner producers is heat? Thanks for your time.

Matt Fitzgerald

One week later (Dr. Noakes is a very busy man), I received the following reply:

Dear Matt,

Great question for which there are no data available.  It does not make sense that there should be a benefit from training in the heat for running in the cold – so that is why no one has ever studied that possibility. It is too bizarre to consider. But often what appears to be bizarre actually works.

However realistically there should be no benefit.  Training in the heat works by preparing the body for running in the heat (obviously) and the benefits are largely in reducing the amount of heat that the body produces during exercise and the relative ease with which that heat can be lost.  The only adaptation you require for running in the cold is to use more clothing – training cannot improve on that simple behavioural adaptation.

Finally note that being small is perhaps the greatest benefit for exercising in the heat.

With warm regards,

Tim Noakes

Although quite graciously expressed, this reply completely dismisses the hypothesis I had presented to Noakes. Not only did he believe that the notion of heat acclimatization training improving endurance performance in temperate conditions was unrealistic, but he was also surprised that the very idea would ever occur to anyone. He might have even doubted my fitness to author running books!

Thankfully, subsequent communications seem to have restored my reputation with Noakes, who even wrote the foreword to my 2007 book, Brain Training for Runners. Quite an honor for me, as I consider him the greatest exercise scientist in history.

However, my tremendous respect for Tim Noakes won’t stop me from claiming sweet vindication regarding this matter of heat acclimatization training improving endurance performance in moderate conditions. Turns out it does! Ha!

Recently Santiago Lorenzo at the University of Oregon was visited by the very same “bizarre” idea that occurred to me at the beginning of 2004. Only Lorenzo had the skills and resources to actually test it.

He recruited 20 highly trained cyclists and had them complete a performance test in temperature conditions on two occasions, separated by 10 days. Between the tests, all 20 cyclists completed a prescribed training program, but 12 of them did it in a controlled, hot environment (100 degrees) while the other eight performed their workouts in the same temperate conditions (55 degrees) as the performance tests.

The 12 cyclists who underwent heat acclimatization improved their performance in the temperature performance test by a massive 7 percent. The summary article I read does not say whether the control group exhibited any performance improvement but implies that it did not, and I assume it did not.

The authors of the study attributed the performance-boosting effects of heat acclimatization training on endurance performance in cool conditions to improved efficiency in heat dissipation and increased blood volume. They also found evidence that it caused some changes in muscle cell enzymes, which may have contributed to the effect as well.

Lorenzo and his colleagues plan to conduct future studies to pinpoint the specific mechanisms underlying the performance benefits and to determine whether heat acclimatization enhances performance in a real-world temperate time trial.

In the meantime, forget altitude camp. I’m going to heat camp before my next big race!


Check out Matt’s latest book, RUN: The Mind-Body Method of Running by Feel.

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