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When looking at cycling performance in the heat, previous studies done in controlled labs (versus outdoors) have shown that power is “markedly impaired” in a hot (above 86 degrees F) environment. One recent study in Medicine and Science in Sports and Exercise studied the effect of heat acclimatization on cycling time-trial performance and pacing. Researchers found that much of performance loss in the heat may be actually mitigated through acclimating.
Although many of us may have never thought of air density playing a major part in a hot race, this study cited that an increase of 20 degrees (Celsius) in ambient temperature will reduce air density by approximately 7 percent, allowing for an approximate 6 percent increase in speed for a given power output.
For the test, the participants rode three time trials: one with no acclimation, one with five days and one after two weeks. To acclimate, each spent four hours outside (not exercising) per day and otherwise stayed indoors in an air-conditioned environment. In addition, two TTs were performed in cool conditions, one pre-study and one post-study, and were then averaged for comparison data.
Researchers found that some of the test cyclists’ power was restored after a one-week acclimation period and much of it after a two-week period of acclimation. Furthermore they found that due to a reduction in air density, their speed was not significantly different between the cool TT and the acclimated TT.
The bottom line: If you’re headed to a hot race and wondered whether acclimation will really help you perform better, the answer is that it will! One week of acclimation will help and two weeks will help even more. While it may not be realistic to arrive at every warm-weather race destination a week or two in advance, for certain “A” races like Kona, leaving time for acclimation could be worth it. Also, if you’re discouraged at the thought of your splits, keep in mind the silver lining of a small increase in speed due to reduction in air density. An appreciation of this free speed, if nothing else, can help you approach the race with a more positive frame of mind.
Prepping for a hot race
If arriving at a race a week or more ahead of time isn’t in the cards, set yourself up for success in other ways.
– Do your key race-prep workouts in hot conditions that mimic your anticipated race temps.
– Practice taking in more sodium and fluids during long training days.
– Use a scale before/after training to track sweat loss.