As the temperatures rise and riding season ramps up, cyclists continuously look for ways to beat the heat and gain an edge in performance. Heat training is a strategy which can meet both of these needs.
The positive effects of heat training benefit every level of cyclist. Cycling coach Zack Allison of Source Endurance says, “Heat training is for everyone.” He recommends it for all of his athletes to increase their performance, comfort, and even fun levels during hot summer bike rides. “Overheating is never fun.”
Many cyclists may have heard that training in the heat can help improve endurance performance and heat tolerance, but perhaps they aren’t sure how or when to do it, or if they even should. Below, we explain what cyclists should know about heat training—which is also sometimes called heat adaptation or heat acclimation/acclimatization.
What is heat training?
Heat training is the act of intentionally exercising in a hot environment for a designated amount of time and intensity in order to stimulate physiological adaptations from a raised core body temperature. While athletes may get some benefits from simply spending time out in the heat or riding in the heat, this doesn’t mean they are always heat training.
Exercising and living in hot temperatures provides an outside stimulus which prompts the body to make physiological changes to adapt to these strenuous conditions. Some of the ways the body adapts to the heat include increasing sweat rate to dissipate heat from the body, reducing concentration of electrolytes in sweat, increasing blood plasma volume to deliver nutrients and help the body cool itself, reducing resting body temperature, and reducing heart rate at given exertion levels.
These physiological changes may happen just from living in hot climates but won’t have the same beneficial effects as formal heat training. To stimulate these changes, a rider needs a certain level of exposure to the heat for certain quantities of time.
How do you accomplish heat training?
Heat training protocols vary greatly, but it is generally accepted that eight to 14 heat training sessions for 45 minutes or longer are adequate to produce physiological benefits to endurance performance and heat tolerance during exercise. Studies on heat training protocols have been tested in temperatures between 90 and 104 degrees Fahrenheit, and training sessions often are on consecutive days.
Short-term heat acclimation protocols of seven days or less have also been shown to produce physiological benefits for endurance athletes, but they are less effective than longer protocols between eight and 14 days according to an article published in 2014 in Sports Medicine.
Some protocols even include elements such as intentionally dehydrating the body and creating specific climates, such as high or low humidity.
High-intensity training sessions have been shown to be more beneficial than low-intensity training sessions for heat training, although low-intensity exercise can also be helpful according to a scientific review article published in 2015 in the Scandinavian Journal of Medicine & Science in Sport.
That being said, not everyone has the time, resources, or need to complete a regimented heat training protocol. If you live in a hot climate, heat training may be as easy as going out for a ride during the hottest part of the day and doing that for consecutive days.
For those who don’t live in a hot climate or have access to a hot climate prior to a specific event, heat training may be more expensive and time intensive when additional equipment or travel is needed. Cyclists may travel to a location with a hot climate or use space heaters, saunas, heat chambers, or any number of creative ways to simulate a hot environment.
How do you stay safe while heat training?
Make sure to drink 20 to 32 ounces of fluid per hour while heat training to reduce the risk of heat exhaustion or heat stroke.
If you are intentionally restricting fluid during heat training, do not lose more than two percent of your body weight from sweat. Start rehydrating immediately if you lose more than two percent of your body weight. To determine this, weigh yourself before starting the session and periodically throughout the session depending on how long it is. Depending on the protocol, you may want to consider being monitored by a physician or medical professional during the heat training sessions.
Develop a heat-training protocol with a trained professional—a qualified coach or sports physician—to maximize the gains of the protocol in context of the environment and equipment the athlete has available.
Learn to recognize heat-related illness: According to the Centers for Disease Control and Prevention, signs of heat exhaustion include heavy sweating, thirst, weakness, dizziness, headache, nausea, irritability, elevated body temperature, and a decrease in urination. If left unchecked, heat exhaustion can lead to heat stroke, which can eventually prove deadly. Signs of heat stroke include profuse sweating or hot and dry skin, confusion, slurred speech, loss of consciousness, a very high body temperature, and seizures. If you notice any of these symptoms, stop your workout and seek treatment.
When should cyclists do heat training?
If you are planning to compete or ride in a hot climate, heat training has been shown to have the most benefits for performance and comfort on endurance exercise in the heat, as compared to shorter high-speed efforts like sprinting.
Heat training has been shown to be the most beneficial for athletes completing endurance exercise, like time trials, in hot climates. These training sessions stimulate the body to reduce heart rate for a designated power output, reduce core body temperature both at rest and during exercise, improve perceptions of thermal comfort (make it feel more comfortable in hot temperatures), and increase time to exhaustion during time trials.
One study shows that short-term heat training (five 60-minute sessions) improves aerobic performance, while other research demonstrates that heat training improves cycling time trial performance in the heat by as much as 16 percent (though it didn’t improve VO2 max or peak aerobic power output).
While there is more clear evidence to support using heat training to improve performance when actually cycling in the heat, results are mixed as to whether heat training benefits performance while riding in cool temperatures.
Studies show that if you are completing heat training to perform in a hot event, the closer to the event date the better. For every day that you are not exercising or living in the heat, there is about a 2.5 percent loss in heart rate and core temperature cooling gains.
While athletes of all abilities benefit from heat training, the physiological benefits may stay longer for more highly trained cyclists compared to cyclists who are less trained, based on their VO2 max. Adam Mills, MSEd, RCEP, coach and owner of Source Endurance, explains that “being heat trained will always benefit performance,” due to the physiological adaptations such as increased plasma volume and decreased resting heart rate. These adaptations will contribute to higher output in training, which will contribute to a strong foundation of fitness overall.
If you are not able to complete heat training right before your hot event, do not fear, as scientists have come up with ways to top up the benefits previously gained. A study published in 2021 in Medicine and Science in Sports and Exercise showed that five days of heat training were enough to regain the sweat adaptation benefits of a 10-day heat training regimen performed more than 30 days prior. If you have a specific event you are using heat training for, ideally you are completing the heat training as close to event day as possible. If this isn’t possible, a refresher of five days of heat training could be helpful.
Even for non-professional cyclists, if you are planning to ride in hot temperatures, heat training prior to those rides can reduce your suffering, increase your overall endurance performance, and reduce your risk of heat stroke and other heat-related medical issues. These benefits will exist no matter what level of rider you are.
Do you want to suffer in the heat now, during heat training, to suffer less later, during an event? Do you have the means to complete a heat training protocol leading up to a hot event? It’s important to assess your personal cycling goals, time, and resources to determine if heat training is worth it for you.
What doesn’t heat training help you accomplish?
While studies have shown heat training to be beneficial for endurance performance, the same cannot be said for short duration efforts, such as sprinting.
A systematic review published in 2014 included eight studies investigating the effectiveness of short-term heat acclimation training on physical performance. (Limitations for this review include the studies having a cumulative moderate level of bias, only two of the eight studies were randomized controlled trials, and only one of the studies focused on women participants.) The researchers concluded that seven or less heat exposure sessions may benefit aerobic-based tests but not anaerobic power efforts.
Not only has heat training not shown to benefit athletes performing short efforts, but the stress put on the body while exercising in the heat may be detrimental to training for sprint events.
Heat training has been shown to be most effective for endurance exercise in the heat. Its caveats include that it may or may not help with endurance efforts in cool temperatures, and it probably doesn’t benefit anaerobic type efforts in either hot or cool temperatures.
The bottom line on heat training for cyclists
Cyclists of all levels can benefit from heat training, especially if they are planning to ride or compete for 20 minutes or more in the heat. This heat training depends on if they have the time and resources to complete eight to 14 days of consecutive heat training sessions close to their event, and/or the addition of a five-day heat training top-up closer to their event. Many protocols exist for heat training, and cyclists should assess their goals, time, resources, and interest in preparation to decide if heat training is worth it for them and how to integrate it into their performance plans, without risking safety.