The Surprising Benefits of Training in the Heat

One of the highest sweat rates ever recorded was that of marathon runner Alberto Salazar at the 1984 Olympics in Los Angeles. In the months leading up to the games, which were expected to be oppressively hot, the marathoner was put through a regimen of temperature acclimation training with the goal of helping him adapt to running in the heat.

While Salazar placed only 15th overall, the program was deemed a success, physiologically speaking—vitals taken after the race found that Salazar’s hormonal and thermoregulatory systems were completely normal. His body had compensated by causing him to sweat at an incredibly high rate—about three liters per hour, compared to the roughly one liter per hour for an average human.

Researchers have been looking at the effects of heat on athletic performance for decades, and their results have been consistently surprising. Studies have found that, in addition to an increased rate of perspiration, training in the heat can increase an athlete’s blood plasma volume (which leads to better cardiovascular fitness), reduce overall core temperature, reduce blood lactate, increase skeletal muscle force, and, counterintuitively, make a person train better in cold temperatures.

In fact, heat acclimation may actually be more beneficial than altitude training in eliciting positive physiological adaptations, says Santiago Lorenzo, a professor of physiology at Lake Erie College of Osteopathic Medicine and a former decathlete at the University of Oregon. “Heat acclimation provides more substantial environmental specific improvements in aerobic performance than altitude acclimation,” he says.

And in contrast to the live low, train high philosophy, we more quickly adapt to heat stress than we do to hypoxia. In other words, heat training not only does a better job at increasing V02 max than altitude, but it also makes athletes better at withstanding a wider range of temperatures.

Athletes can adapt to heat in one of two ways. The first is through incremental improvements in tolerance over time—work out in the heat a little bit every day, and eventually your body will dissipate heat more effectively. The second way is through thermotolerance, which is a cellular adaptation to an extreme heat experience, like suffering such severe dehydration after a run that you need an IV.

Essentially, if you shock your system, your body will be able to withstand greater temperature stresses later on. But successful heat adaptation is difficult—and clearly dangerous—to achieve outside of controlled settings. Lorenzo explains that performance gains are possible only when athletes elevate their core body temperature, and without careful monitoring, it’s possible to elevate your core temperature to lethal levels.

When performed safely, however, heat training can have extraordinary effects. This phenomena fascinates Chris Minson, a professor of human physiology at the University of Oregon, who studies heat acclimation responses in athletes. According to his research, heat training can expand blood plasma volume, but Minson says there also seem to be inexplicable changes to the heart’s left ventricle, which helps to increase oxygen delivery to the muscles.

In addition, he says that athletes who train in warm temperatures generally get better at regulating heat by sweating earlier, as Salazar did, or developing a colder resting body temperature. A 2011 study by a group of researchers in New Zealand also found that overall volume of blood plasma increased at a greater rate when athletes did not drink water during exercise. While some coaches are carefully experimenting with dehydration, Minson and Lorenzo are not because it adds too much additional stress.

However, they do say that this type of training can be beneficial because it produces a higher number of “heat shock” protein cells. Ahead of Western States this June, ultrarunning coach Jason Koop worked on heat training with Amanda Basham and eventual winner Kaci Leckteig. Koop believes this type of acclimating is a good example of blending an academic concept with real-world training. But, says Koop, “at a certain level, you have to compromise training quality for the heat acclimation.

Acclimating to the heat is additional stress [on the body], just like more miles or intervals, so you can’t simply pile it on. Something on the training side has to give.” One method of heat acclimation that Minson uses with his athletes is to do hard workouts on colder days or earlier in the morning, and then start training in hotter conditions with less intensity. He is also looking into adding heat in ways that wouldn’t require an athlete to train in high temperatures at all—using hot tubs, for instance.

All this being said, not everyone responds to heat at the same rate or with the same physiological gains, which makes it similar to altitude training in that it might make a high-performing age grouper, college athlete, or elite a little better, but it won’t compensate for intelligent, consistent training.

How to Incorporate Heat Acclimation into Your Training Schedule

When acclimating to heat, you’ll be forced to compromise training quality, says Koop. While he understands the benefits of heat acclimation, he still prioritizes smart, solid training. But if you want to incorporate heat into your workouts, here’s how he recommends doing it safely.

1. First, pick a protocol (sauna, hot bath, or exercising in the heat) that minimizes the impact on training, both physically and logistically.

2. Koop most commonly recommends that his athletes use a dry sauna immediately after running. “It doesn’t impact training nearly as much as running in the heat, and the effects are similarly positive,” he says. He often tells his athletes to not drink water during these sessions to enhance the effect. Koop recommends spending 20-to-30-minutes in the sauna, depending on tolerance.

3. Koop says that when he has his athletes exercise in the heat—either naturally or by wearing extra clothing to simulate the experience—it will be on a long, slow day for 60 to 90 minutes. The time completely depends on the athlete’s tolerance and previous experience. But he stresses to not do this on a recovery day, because heat training is an added stress on the body. Koop recommends drinking 30 to 40 ounces of an electrolyte drink per hour during these sessions And for safety, he advises using low-traffic sidewalks and bike paths—not trails.

4. Despite the benefits of heat training, Koop reminds his athletes that running in the heat is extremely difficult and usually replaces a hard day. “You are substituting one potential gain for another one,” he says. In other words, use it carefully.

Source: The Surprising Benefits of Training in the Heat – Outside Online

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Although training in the heat offers some benefits, it does have drawbacks too.

The Mayo Clinic reports exercising in a high temperature environment can sometimes result in heat-related illness. The most common illnesses include:

Heat cramps – These are painful muscle contractions. Though caused by excessive heat, they can also occur when body temperature is normal.

Heat syncope – If the client feels lightheaded or faints due to high heat exposure, heat syncope may exist.

Heat exhaustion – This occurs when the body’s core temperature approaches 104 degrees Fahrenheit. Symptoms of heat exhaustion include nausea, vomiting, headache, and clammy skin.

Heat stroke – If the core body temperature exceeds 104 degrees, heat stroke can occur. This results in feelings of confusion, heart rhythm issues, and vision problems. Immediate medical attention is necessary to help preserve the brain and organs. If untreated, death can result.

Heat stress and heat-related illness are a major concern. Reduce this concern by helping clients acclimate to the heat and humidity common in summer training sessions. Research reveals that the human body goes through certain changes when exercising in a hot environment. Our core body temperature increases, first rapidly then at a slower rate. Metabolic rate increases as well, especially in heat stress conditions. Blood flow is altered to transfer the heat from our internal body to our skin, where it is released via our sweat. These changes are necessary to help prevent the body from overheating.

Though the human body is good at adapting to warmer climates, heat acclimation training improves this response. This enables clients to exercise more safely in hot environments. It also improves their performance. What does an effective acclimation program look like? A study on endurance athletes found that, for those not acclimated to the heat, high intensity exercise increased fatigue and weakened performance. Therefore, a lower-intensity workout regimen is recommended. At least until the client becomes used to the heat and humidity.

Another piece of research noted that 6-7 high-heat exposures are needed to improve adaptation. Each one should be at least 30 minutes in length. If you live in an area that is not particularly hot or it isn’t summer, there are a few ways to add heat to an exercise session. These include using a sauna or working out in heated water. Wearing multiple layers of clothing will also raise the body’s internal temp.

Some gyms and fitness facilities have an athletic chamber. This is a room that enables you to raise the heat and humidity to specific levels. You might also find these rooms at universities and colleges.

Yes, heat acclimation helps boost performance. But its number one goal is to help clients avoid heat illness, heat exhaustion, or heat stroke. Here are a few more safety tips that will help too:

Drink lots of water. Dehydration occurs faster in hot environments because heat increases sweat rate. This makes hydration critical when exercising in hot weather. Harvard University suggests consuming 2-3 cups of water per hour if you’re sweating a lot.

But don’t overdo your water consumption. It’s also important to note that you can drink too much water. This is called water intoxication and reduces the sodium in the bloodstream. This can cause headache, nausea, and vomiting. In severe cases, blood pressure rises, it’s harder to breathe, and the client feels confused.

Consume sports drinks for lengthy trainings. During longer workout sessions, water may not be enough. Because your sweat contains many chemicals and salts, these need replacing. In this case, sports drinks can replenish the electrolytes lost via excessive sweat. Sports drinks also supply a limited level of carbohydrates. This gives your body the energy it needs to continue to work out.

Avoid exercise during extremely high temperatures. If you live in a place where extreme heat is common, exercise when it’s a bit cooler outside. This limits the likelihood that you’ll suffer a heat illness. What’s the best time of day to exercise in this type of environment? Either early in the morning or later in the day.

Pay attention to the humidity. When it is both hot and humid outside, the body responds differently than in dry conditions. Specifically, humidity increases your sweat rate, which impacts your hydration. The Cleveland Clinic suggest not exercising if the humidity is over 80 percent and it’s 80 degrees or higher.

Wear the right clothing. Your body must be able to sweat to better control its internal temperature. Lightweight clothing assists with this. Wearing clothing in lighter colors is preferred as well since they don’t absorb as much heat as dark colors.

Monitor your heart rate. Heart rate increases 10 beats per minute for every degree the body temperature rises. So, wearing a heart rate monitor helps clients better identify whether their cardiovascular system is experiencing heat stress. Heart rate monitors can also signal if dehydration exists.