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Acclimation and Heat Training! Embrace the Heat Now and Crush Your Races in the Fall

Feb 24, 2021

The summer heat is already upon us and while there’s probably a unanimous groan that comes with that statement there should also be a bit of excitement.

If you’re a runner you’re all too familiar with the physical misery that comes with running in the Kansas heat. You know when it feels like you’re running with a 40lb vest on? It’s a real struggle to get through those summer workouts but here’s why you should look forward to the heat and how to use it to your advantage in the fall.

You may have heard of the “live high train low” philosophy for elevation training. This is a model that would see athletes live in a high altitude and train in a lower altitude with the ultimate goal of maximizing low altitude performance through physiological change. This training philosophy is widely used by coaches and considered one of the best methods for maximizing performance for higher level athletes. 

A similar concept exists with the concept of “train hot, perform cool”. The idea is that you use the physiological adaptations that come with training in the heat, called heat acclimation, and reap the rewards in the cooler seasons. 

Your body struggles to perform at a high level in the heat because you’re under a significant amount of physiological stress compared to a cool environment. Your resting heart rate is higher, muscle function becomes hindered faster and our perceived rate of exertion has a higher base.

Over time, however, this increased physiological stress allows for big changes in our fitness. Research has shown that heat training leads to things like increased perspiration, increased blood plasma volume, increased mitochondria synthesis, and a reduction in resting core temperature.

Increased perspiration? Is sweating more a good thing? The answer is YES. 

During exercise, 80-95% of heat dissipation comes from evaporation or sweating. With this increase in perspiration comes the ability to more easily get rid of excess heat and ultimately perform at your maximum efficiency. 

As you continue training, you’ll also begin to sweat earlier in your workouts. This comes from an adaptation to your sympathetic nervous system. Sweating earlier means that you can beat the coming increase in core body temperature that comes from exercise. 

Increased blood plasma volume is another reward for your hard work in the heat. With this new blood volume your heart is able to move more blood to the necessary tissues without needing to pump as hard or as fast. It also helps with that additional sweating you’ll be doing as sweat actually comes from your blood plasma. More plasma volume = more sweat = more cooling. Weird right?

All of this brings on a new challenge, however. Hydration. On average, we lose about a liter of water per hour during exercise from sweat and moisture lost through breathing. This number can be even higher in the heat and more so for non acclimated athletes.

So when training in the heat you must maintain that blood plasma level with adequate water intake. This may mean drinking more fluids than you do currently. Getting proper minerals (sodium, potassium, magnesium, etc) in the heat is important as well. There are plenty of electrolyte tablets on the market, like Nuun, that you can throw in your water before a run. 

Not only will all of these changes go towards improving your VO2 and making you a better aerobic athlete, but it will specifically set you up for crushing your events in the fall. These physiological adaptations all contribute to improving your performance in a cool environment.

Training in the heat can be difficult, and potentially dangerous if you’re not staying hydrated, but the benefits that come from it are hard to beat. Use the heat to your advantage this summer. Make friends with it and reap the rewards once all of those postponed races come back around this fall. 

If you have questions about training in the heat, reach out! I’d be glad to give some additional tips on what you can be doing to maximize your potential.