With the current heat wave sweeping much of the planet, it's good to know that your additional suffering due to sweltering conditions isn't for nothing.
Researchers at the Department of Human Physiology, University of Oregon have shown that training in hot conditions improves aerobic capacity — even when subsequently performing at a cooler temperature.
Using trained, competitive cyclist as subjects, the researchers had one group perform 90-minute ergometer sessions at 50% of their V̇O2max at a room temperature of 104 degrees while a control group did the same work in a room set at 55 degrees. Each group performed one session per day for 10 days while maintaining their normal training.
"The results were pretty astonishing as the athletes who did heat acclimation work improved lactate threshold, V̇O2max, and time-trial performance in both cool and hot conditions, while those who did the same work in cool conditions didn’t show improvement in any of these areas."
The heat acclimation group individual data demonstrate a clear and consistent performance improvement in both the cool and hot environments, while the control group shows no tendency toward such trends for all variables.
"In fact, the authors claim this is the first research to show that heat acclimation training increases lactate threshold while later performing in a cool environment. In addition to the lower blood lactate levels measured after heat acclimation in both environments, we are the first to report that the threshold at which blood lactate levels begin to rise also is delayed by heat acclimation."
The performance gains observed are similar to what has been shown possible through sleeping at high elevations, and are expected to be retained for 1 or 2 weeks after discontinuing heat acclimation. This is big news for the vast majority of endurance athletes living at lower elevations without access to altitude chambers or high-elevation training camps.
With how hot it's been in much of Colorado it will be interesting to see whether there’s an additive effect to combining high-elevation sleep with lower-elevation heat acclimation beyond what’s already been shown through “live high, train low" scenarios.