Heat Training
by GRP runner Katie Kellner
As I'm sure you all have noticed, the temperatures have been climbing over the last few weeks. While the warmer weather can be invigorating, it can also make running more challenging. Here are some tips to make summer training a little easier, and ways to adjust your paces based on the conditions.
Why is running in the heat so hard?
It is obvious from the splits on our watch and the excessive sweat on our shirts that we strain more when running in the heat, but why is this so? When our temperature rises to an uncomfortable level, the body has two methods to try to cool itself. First, blood, which carries heat, is redirected to the surface of the skin. This allows the blood to dissipate that heat to the surroundings. While this has a cooling effect, it also means that less blood is flowing to the working muscles, so these organs get less oxygen. Thus, the same workload will require more energy than running in cooler temperatures. Second, the body tries to cool itself by sweating. When sweat evaporates from the skin, it has a cooling effect. Unfortunately, high humidity, which indicates high moisture in the air, makes evaporation more difficult and sweating less efficient as a cooling mechanism.
Can I get fitter by running in the heat?
Heat acclimatization is a true phenomenon! In fact, heat training has been called the "poor man's altitude training". Both heat training and altitude training have similar effects on the body. When one goes up to altitude, there is less oxygen in the air. Therefore, the blood carries less oxygen to the working muscles. Over time, the body increases its blood volume so that it can transport more oxygen at one time. Similarly, with heat training, blood is redirected to the surface of the skin to facilitate cooling. In this process, less blood can carry oxygen to the muscles. To adapt to the heat, the body increases its volume of blood so it can bring more oxygen to the muscles. Therefore, both altitude training and heat training increase blood volume to facilitate oxygen transport. Different types of training, but similar effects!
How do I adjust my paces in warmer conditions?
As a coach, I get a lot of questions about whether it is appropriate to adjust training paces on hot days and if so, how to do this properly. It isn't as straightforward as it sounds, since temperature, humidity, and amount of sun all play into the equation. Truthfully, my favorite method is to go by effort rather than pace, meaning you start at a pace that you can maintain for the entirety of the workout, expecting it to be slower than a pace you could maintain in cooler temperatures. However, I know many runners are "numbers people" and having a specific formula can help you see if you are on the right track. My favorite formula comes from coach Mark Hadley of Maximum Running Performance. He suggests calculating the number of degrees above 60 it is outside. Let's say it is 83 degrees, so that would be 23. Then, add 5 to 10 degrees if it is humid out. We will add 7 for a decently humid day and make our new total 30. Multiply this number by 0.15% which for us is 4.5%. Increase your pace by that amount, 4.5% in this example. For example, 8:00 would become 8:22 pace.
How do I prepare for a hot race?
Perhaps you are preparing for a race where you know it is going to be hotter than it is now. The race may be later in the summer or in a location with a much warmer climate than where you live. In order to perform your best, you should aim to begin the heat acclimation process during your training. This can be done by running in extra clothing, spending some time in a sauna, or running at the warmest time of day. Only use these methods if it is not already warm where you live. You shouldn't further stress your body when it is already very hot out!
Tips for training in the heat:
1. Stay hydrated
Staying hydrated is the best way to beat the heat. The more hydrated we are, the more we can sweat. I recommend carrying a water bottle around with you throughout the day. Having water near you increases the likelihood of drinking at moments you otherwise would not. I recommend rehydrating with electrolytes, rather than simply water, and using them throughout the day if you are feeling particularly sluggish.
2. Hydrate during the run
Taking in some fluid while running, especially during tempos and long runs, can make a big difference in both how you feel and how fast you are able to run. Carrying fluid may initially seem irritating, but there are great handheld water bottles and backpacks on the market. If you are racing or practicing fueling for race day, you should drink something with both electrolytes and simple sugars and aim to get in 100 calories every 30-45 minutes. If you are just trying to feel better during a hot run, you can worry about refueling when you are finished and use water or a low-calorie electrolyte drink.
3. Pouring water vs. drinking water
Let's say you are out on a run and you have a bottle of water. You are very overheated. Should you drink the water or pour it on your head? Some fun studies have actually looked at which method is more efficient for body cooling. Drinking a cold beverage will keep you hydrated and facilitates sweating, but pouring water on your body allows for more efficient evaporation off the skin's surface. The journal, Temperature, conducted a study on the matter and found that while drinking 250 ml of cold water dissipates 81 kJ of heat, evaporating that water off your skin rids the body of 607 kJ of heat! This suggests that pouring water is significantly more effective. However, there are a lot of other factors to consider. If you pour 250 ml of water on your head how much is landing on your skin and how much is dripping to the pavement? The humidity also plays a big role in how efficient evaporation off the skin is. Therefore, if you can, drink and pour!
4. Seek out shade
Direct sunlight can quickly increase your body temperature. Therefore, anything that blocks the sun from the surface of your skin will help immensely. Running on trails or other shady paths is ideal, but not always possible. Hats can protect your face from the sun and sunglasses can trick your brain into thinking it is less sunny than it truly is. Wearing sunscreen can even make us feel noticeably cooler because we won’t absorb as much of the sun’s radiation. Similarly, lighter colored clothing reflects more of the sun’s rays, so avoid wearing black on hot days.