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Coaches Blog

Affordable Heat Acclimation Strategies for Endurance Athletes

With climate change, more races are experiencing hotter or more humid conditions. Additionally, the global rise of endurance sports means locations in hotter or more humid climates are hosting these events. 

For example, the T100 triathlon took place in Singapore in April and athletes faced temperatures as high as 95 degrees F, with very humid conditions. 

Pro athletes who live in cooler climates can plan training camps in locations that mimic the racing conditions they expect to encounter. (Pro triathletes are headed for places like the Philippines and Malaysia for extended heat preparations.) This isn’t a likely option for most of us age-groupers. So, let’s explore some affordable and effective strategies to prepare for a hot, humid race. 

Heat Acclimation Basics for Endurance Athletes

If you’re planning to complete an endurance event where hot, humid conditions are expected, heat adaptation should be part of your training plan -- especially if you don’t live in a hot, humid climate.

What is heat acclimation for endurance athletes?

Heat acclimation is the process of steadily increasing your body’s tolerance to hot and/or humid conditions. It reduces strain on your cardiovascular system, improves your ability to perform in hotter climates, and reduces your risk of developing heat illnesses. 

Heat training can improve your ability to regulate your body temperature, cardiovascular function, and fluid-electrolyte balance. 

How long does heat acclimation take?

Most athletes can see improvements with 1-2 weeks of daily heat exposure during training sessions. There are many strategies and methods of acclimatization. Some recommend 1-2 weeks of daily heat exposure for about 90 minutes, while others recommend 2-4 weeks of shorter exposure sessions. 

Most experts and coaches agree that mimicking the conditions you expect to race in during your acclimation process is essential. So, if you’re planning to race in a hot, humid environment, you should replicate that as best as possible. The same if you expect to experience hot, dry racing conditions. 

Active vs. Passive heat acclimation strategies

Active acclimation methods include exercising in hot conditions. Athletes might add hot yoga sessions or move bike trainers or treadmills into climate-controlled rooms. Other athletes might wear extra layers and train during the hot parts of the day. 

Passive heat acclimation strategies include things like sauna sessions immediately after a workout, taking a hot shower, or sitting in a hot tub. These strategies are “passive” because you’re not working your body, but you are keeping your core temperature elevated for prolonged periods. 

For best acclimation results, it’s best to have daily exposure to heat. Start at the lower end of the duration range and slowly increase the length of time. Many athletes experience substantial adaptation within 7-10 days of consistent heat training. 

The primary goals of heat training are lower exercising heart rate, lower core temperatures, and a better sweat response. Monitor your heart rate response throughout your heat acclimation to track your progress.

Heat Acclimation Strategies for Endurance Athletes

Here are some easy, generally accessible, and relatively inexpensive ways to add heat acclimation strategies to your training routine. 

Build a DIY Hot Box

Before the Tokyo Olympics, many endurance athletes got creative with their heat adaptation. Triathlete Katie Zaferes built a “hot box”—she put her bike trainer in a large tent with a heater and humidifier to raise the temperatures to about 90 degrees and the humidity to about 80%.

Perhaps you don’t have room for a “hot box,” but you could move your trainer into the bathroom or laundry room and run the hot water or dryer for a bit to create a warm, humid environment for some training sessions. 

Some athletes hang builder’s plastic or SilvaRboard insulated foam boards around a small portion of their garage or basement and add a portable heater as a temporary “hot box” large enough for a bike trainer or treadmill. 

Train in the Afternoons

Most endurance athletes are accustomed to getting out early to take advantage of the cool morning temperatures for runs and rides. If you’re acclimating to a hot-weather race, consider moving your workouts to the hottest parts of the day. 

Layer Up

If the temperatures where you live still don’t get close to the temperatures you expect to face on race day, add a layer or two of clothing. A rain jacket and tights can raise the perceived temperature several degrees. It’s an uncomfortable but generally effective heat adaptation strategy.

Hit the Hot Tub/Sauna/Shower

Does your pool or gym have a hot tub or sauna? Add a few sauna sessions each week after your regular swims or other workouts. If that’s not an option, consider jumping into a hot shower immediately after each training session to keep your core temperatures up for a longer period of time. 

Reduce AC Use

Leading up to and when you arrive at your hot race location, keep your room at a moderate temperature. Using air conditioning to keep your room or house too cool can make it more difficult for your body to acclimate. 

If you don’t have control over the thermostat, layer up. Stay comfortable but on the warmer side. 

Other Factors to Consider

When you begin any heat acclimation protocol, be sure to lower the intensity levels of your workouts, especially for the first few workouts. Your body will be working overtime in the heat. 

If you are using a “hot box” strategy (performing workouts in artificially hot/humid conditions), many experts recommend doing your key workouts in your typical (cooler) training conditions so you continue to make progress with your training. Leave the “hot box” sessions for less critical workouts that are lower intensity. 

The benefits of heat acclimation typically last for about 10 days after you stop the protocol. So, many athletes reduce or stop their heat sessions about a week before their competition. That gives their bodies time to recover without losing any adaptation benefits. 

Don’t forget to adapt your hydration and fueling plan, too. Your body will probably need a different ratio of hydration and electrolytes in hot and humid conditions. If possible, it’s helpful to get a sweat test to assess your sweat rate and electrolyte loss rate. That will guide your hydration plan most accurately. 

Your fueling needs will also change. You’ll likely be working harder in the heat to maintain your pace. Though many athletes find it harder to consume calories when it’s hot, you’ll likely need more calories per hour during a hot race

A bit of creativity, strategy, and planning can give any athlete the tools to properly acclimate to hot racing conditions. Work with your coach to adapt your training plans accordingly. A quality coach will know how to guide your training and heat acclimation protocols properly. 


Gregg Edelstein is a certified USA Triathlon Level 1 Coach, an IRONMAN University Certified Coach, and a USA Cycling Level 3 Coach based in the greater Boston area. Gregg offers his athletes insight on the principles of exercise, nutrition, sports psychology, and injury prevention, working to make them well-rounded and engaged athletes that share his passion for sport. Gregg can be reached at 



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