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Heat acclimation gives big cycling performance improvements in cool conditions, study finds

  • By Ben Delaney
  • Published Nov. 4, 2010
  • Updated Dec. 14, 2012 at 2:51 PM EDT

A recent study by human physiology researchers at the University of Oregon found that huge physiological gains could be achieved in trained cyclists by doing 90-minute easy rides in high heat for 10 days.

Before the testing, the researchers expected to find improvements in the hot-weather performance of Cat. 1 and 2 cyclists after a heat-acclimation program. But what surprised them was that the physiological improvement translated to cool-weather performance as well.

“The biggest thing we saw was that the heat-acclimation group increased their time-trial performance by 6 percent in cool weather, and by 8 percent in hot weather,” study co-author Chris Minson, Ph.D. told VeloNews.

Researchers measured time-trial performance via power output over a 60-minute all-out effort. While researchers continuously monitored the riders’ wattage, the riders themselves couldn’t see the numbers and only had elapsed time for reference. In the control group of Cat. 1 and 2 cyclists, no improvements were detected over the course of the study.

The study consisted of six days of continuous testing, followed by 10 days of heat acclimation, followed by another 6 days of testing. The heat acclimation consisted of an easy, 45-minute trainer ride in 100 degrees, followed by a 10-minute break and then another 45-minute easy ride.

The cool weather testing was done at 55 degrees. All the temperature-controlled rides were done in a 12-by-12 chamber. The easy ride was defined as 50 percent of VO2 max. During the test period both the control and the test groups continued their regular outdoor training also.

“What was really neat was that we also saw a 5 percent increase in VO2 max in cool conditions,” said Minson, who is a cyclist himself as well as the University of Oregon’s Human Physiology department head. “The question remains for me as to the real-world application. But the lactate threshold, VO2 max and power output increases in the lab were profound.”

So what does all this mean for everyday cyclists who would like to improve their riding? Minson’s answer is less physiologist and more Eddy Merckx: “Ride more.”

“The best thing most riders can do to increase their performance is to get on their bike and ride more. Do weights in the off-season. Lose weight,” Minson said, adding that the study’s results applied primarily to highly trained cyclists. Even then, the heat acclimation is only helpful when done in addition to solid training.

“What people are taking from this unfortunately is that they should do all their training in the heat,” Minson said.

Minson said you could draw a parallel to altitude training: living high and training high will result in less neuromuscular acclimation, not more; one still needs to train with normal amounts of oxygen to see performance gains. “You have the same corollary here: you still have to train fast (in normal weather). But if you can then add heat acclimation on top of that, you will get a boost. I’ve heard rumors of pro teams already putting this to use.”

Researchers say heat acclimation improves one’s ability to control body temperature, increases blood flow through the skin, and expands blood volume allowing the heart to pump more blood. Researchers also concluded that the heat may produce changes in the exercising muscle, including enzymatic changes that could improve the amount of work done by the muscle, but Minson said more research was needed.

Minson joked that he needed to come up with a catch phrase to encapsulate the concept of heat acclimation added into a proper training program. “’Train cool, taper hot’ was one suggestion,” Minson said. “For trained cyclists, this just could mean going for an easy spin on hot days.”

The study, “Heat acclimation improves exercise performance,” was published in the October issue of the Journal of Applied Physiology.

Editor’s note: Delaney is a former editor in chief for VeloNews. A journalism graduate of the University of New Mexico, Delaney is responsible for all editorial content online and in the magazine. Delaney joined VeloNews in 2005 as managing editor, having worked previously for The Santa Fe New Mexican, Bicycle Retailer & Industry News and as a freelance writer for various titles. He’s a former (but never very good) Cat. 1 racer. He lives in Boulder, Colorado, with his wife and two children.

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