The scorching summers temps are coming. Runners know how climate impacts performance, so our instinct is to hide from the heat through early morning runs or retreating to the cool comforts of a climate-controlled gym.
Our physiology makes physical action more difficult in heat. When our bodies heat up, blood is diverted to the skin, where cooling takes place through sweating and evaporation. There’s less blood available to transport oxygen to the working muscles, which makes it nearly impossible to work out hard.
But despite the discomfort, there’s growing evidence runners should embrace the heat instead of trying to escape it.
For decades, researchers studied how heat influences athletic performance over both the long and short term. There’s growing evidence indicating that training in the heat yields a wide array of athletic benefits. Training in heat can make athletes sweat more efficiently, increase an athlete’s blood plasma volume, reduce overall core temperature, reduce blood lactate, increase skeletal muscle strength and, counterintuitively, improve performance in cold temperatures.
Adapting to heat can be difficult, uncomfortable and even dangerous. But with careful monitoring, heat adaptations can be made safely in controlled environments. Thermotolerance, a cellular adaptation to an extreme heat experience, shock your systems into adapting to withstand higher temperature stresses later on. Simulating extreme conditions using a sauna or exercising in a Rocky Balboa-stye sweatsuit helps that adaptation along.
Anticipating extreme heat at the 2017 Western States 100, I spent the two weeks before the race listening to audiobooks in the sauna followed by short and slow runs, training my body to handle dehydration and exercising while overheated. While I grew accustomed to the heat, I also gained unexpected and extraordinary cardiovascular benefits from it, which played a big role in winning that race.
To acclimate safely and without risk of overtraining, athletes need to compromise training volume for adaptations. Here are a few tips on incorporating heat into your workout regimen while also maintaining solid and smart training.
1. If you acclimate by running in hot conditions, it’s important to slow down. Even runners who are supremely comfortable with heat suffer performance loss in hot conditions. It’s essential to adjust your workout times and race paces to reflect how you’ll perform in hot conditions. Likewise, sometimes you need to know how much more effort a workout requires in hot and humid conditions so you can better monitor fitness and progression.
2. Hydration is critical to staying cool and performing your best in the heat. But knowing exactly how much fluid you need to stay cool and replenish what you lose through sweating is tricky. Every runner sweats at a different rate relative to their conditioning, acclimatization and individual physiology. Legendary coach Jack Daniels found that runners with similar backgrounds, training regimens and under identical training conditions differed in sweat loss by as much as 2.5 liters per hour. While I may only sweat at a rate of 1.5 liters per hour, you might sweat at a rate of 4.0 liters per hour, making drinking and hydrating much more critical for you.
3. Running in the heat is extremely difficult and usually replaces a hard day. It’s important to remember that by heat training, you are just replacing one potential gain for another and adjusting training accordingly is essential in maintaining a healthy regimen.