How to Beat & Defeat the Heat
“Perhaps the greatest stress ever imposed on the human cardiovascular system (except for severe hemorrhage) is the combination of exercise and hyperthermia. Together these stresses can present life-threatening challenges, especially in highly motivated athletes who drive themselves to extremes in hot environments.”
This quote from eminent cardiovascular physiologist Loring Rowell underscores the magnitude that heat stress can have on human performance, especially for our community of highly-motivated and performance-focused athletes. **
Training and competing in the heat is unavoidable for many athletes, and places huge demands on the physiology of even the fittest athletes: these situations require the human body to prioritize cooling to combat both external environmental and metabolic (internal) heat. Our bodies will increase blood flow to the skin and increase sweat production to facilitate cooling. Higher rates of sweat production can lead to significant dehydration, one of the most recognized impacts of exercising in high heat situations. This decrease in available water leads to a cascade of biochemical and physiological effects that can negatively impact athletic performance. (I will dive into the critical and extensive topic of hydration at a different time.)
This article will examine a number of acclimation methods to help you perform better in the heat, as well as several options for real-time cooling when training or racing. The heat acclimation protocols I review range in their ease of execution, as do the methods and tips I recommend to facilitate cooling. By the end of this piece, you will have a number of tools to help you improve your heat tolerance before a goal event, as well as actionable methods to stay cool when working hard in hot environments. (Keep reading to get a discount on Icelegs.com)
Preparation can be key to beating the heat.
Athletes can benefit from preparing for competition or training in the heat ahead of time, using various protocols to help induce physiological and mental resilience to high-heat athletic performance. Below, I outline 5 different approaches to improving one’s tolerance to and performance in the heat.
Exposure training: Training in the heat is one of the most accessible and reliable methods of heat adaptation. Protocols vary, but Pryor, et al. suggest a baseline of at least 7 days, with 10 - 14 days preferred. They recommend training bouts of 60 - 90 minutes in a hot environment, building to two hours. As many of you may have experienced personally, the researchers found that fitter athletes tend to adapt more quickly than those with lesser fitness.
Sauna training: Intermittent sauna post-exercise exposure can be an effective way to improve exercise capacity in the heat. A study by Kirby, et al determined that, “Three-weeks post-exercise sauna bathing is an effective and pragmatic method of heat acclimation…” Athletes may not have easy access to a sauna, and those that do should proceed with caution: a host of physiological and health factors make the use of this method potentially prohibitive.
Clothing: One of the easiest and most accessible ways to induce physiological adaptation to exercising in higher temperatures is by adding “extra layers” of clothing during training sessions. A number of studies have examined the effects of training in an upper body “sauna suit,” while others focus on layering with commonly-used pieces of cycling kit, such as a winter jacket, tights, and warm gloves. Commenting on one study, Stevens notes that, “athletes should be aware that training in additional / insulative clothing in a cool environment will not be as beneficial as training in temperatures of 40 - 45°C (104 - 113°F) for purposes of heat adaptation.”
Sports psych prep: Sports psychology plays an important role in athletic performance, and extends to improving performance in the heat. Barwood, et al. examined the impact of four days of 1-hour psychological skills training (PST) on a group of runners. Sessions focused on four areas: goal setting, arousal regulation, mental imagery, and positive self-talk. After completing a 4-day bout of PST, runners “ran, on average 8% farther after PST suggest(ing) that psychological factors can have a significant impact on running performance in the heat.”
Probiotics: Probiotics have been a “hot” topic in health for a number of years, but a study by Shing, et al. caught my attention. The researchers examined the impact of four weeks of daily probiotic supplementation by measuring time to exhaustion (TTE) in study participants. Using a 45 CFU multi-strain probiotic daily yielded a significant increase in the participants’ TTE in the heat. Currently, the physiological mechanisms behind this adaptation are unclear and require more research, as does the use of “probiotic supplementation for performance enhancement” in general.
Some practical ways to help defeat the heat.
Now that I’ve covered a handful of approaches to improve your performance in the heat, let’s look at some straight-forward ways you combat heat in real time, before / during / after a training ride or race.
Various cooling methods can help reduce the impact of heat on athletes.
At this point, my hope is that you’ve learned some methods to improve your athletic performance in hot conditions, as well as a number of tools you can use to keep yourself cooler at different times in your training and racing. These protocols and tools may be used in combination to achieve the outcome of higher quality training and racing when temperatures start to climb.
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**Some important notes for all athletes and coaches: Individual athletes respond differently to high heat environments, adaptation protocols, and cooling interventions. This article does not specifically address the mechanisms of decreased athletic performance in the heat. It does not explore the role of hydration / dehydration in athletic performance due to the extensive scope of that information. And while the methods discussed in this article are presented in peer-reviewed research journals, the information in this article should not be taken as medical or dietary advice, or for the specific prescription or implementation of any of the topics covered.
Rowell, Loring B. “Human Circulation: Regulation During Physical Stress” Oxford University Press, 1986
Pryor, J. Luke, et al. "Application of evidence-based recommendations for heat acclimation: individual and team sport perspectives." Temperature 6.1 (2019): 37-49.
Kirby, N.V., Lucas, S.J.E., Armstrong, O.J. et al. “Intermittent post-exercise sauna bathing improves markers of exercise capacity in hot and temperate conditions in trained middle-distance runners.” Eur J Appl Physiol 121, 621–635 (2021).
Stevens, Christopher J. "Evidence for training in additional clothing as an alternative heat acclimation strategy for athletes." Temperature 5.2 (2018): 101-102.
Barwood, Martin, Richard Thelwell, and Michael Tipton. "Psychological skills training improves exercise performance in the heat." Medicine+ Science in Sports+ Exercise 40.2 (2008): 387.
Shing, Cecilia M., et al. "Effects of probiotics supplementation on gastrointestinal permeability, inflammation and exercise performance in the heat." European journal of applied physiology 114 (2014): 93-103.