Heat

As I write this, there are 26 inches of snow on the ground outside. Perhaps that's the inspiration for an article about heat.

There was a great article about surviving brutal heat in the latest issue of Inside Triathlon. It was written by Torbjorn Sindballe, a fantastic cyclist who unfortunately had to retire early due to a congenital heart defect. He was one of the best cyclists in all triathlon. He won the Ironman-distance numerous times, but never captured a championship in Kona. The heat and humidity are what make Kona famous, along with the atmosphere, the Energy Lab, the geography, and the winds. But the heat is what makes and break champions and potential champions. Sindballe described the risk factors of training in the heat, and how to manage them.

Dehydration. When we sweat, we lose fluid. Dehydration can increase core temperature, make us feel lethargic, and increases use of muscle glycogen. Since we can only store several hundred grams of carbohydrates in our body, this isn't good. Glycogen stores some amount of water, but not a lot. Sweat rates range from .5- 2 liters per hour, but absorption rates range from 1.3-1.4 liters per hour. If you sweat more than 1.4 liters per hour, you're in trouble.

Hyponatremia- the opposite of dehydration. Contrary to popular belief, this does not occur due too much water, but the concentration of sodium in the body. Too much water can dilute sodium levels, which can degrade performance, or, worse, even kill you.

Overheating. Interestingly, the latest research on exercise performance shows that in extreme conditions such as Hawaii it is not muscle fatigue or glycogen depletion that causes deactivation of muscle fibers, but core temperature. If the core temperature rises to a certain point, the brain will save the body by deactivating muscle fibers. Heat balance is critical, and it's a huge disadvantage to larger people. Heat can literally be an insurmountable barrier to a personal record in any given event. It's no wonder that running records are set in mild conditions between 5-15 C or 40-60 F. The more extreme the conditions, the less weight you must have to perform at a particular pace. In other words, at any given temperature, a smaller athlete is going to be less affected by heat and humidity. That's great news for me!

Economy- This refers to the distance you cover with a certain amount of energy. This is why technique is so crucial in endurance events. Bad technique means you have to use more energy to cover a certain distance. Optimizing biomechanics and technique will help you manage extreme conditions. You must also do a lot of goal-pace work. Don't try to go faster on race day. By the way, cramps are not the result of electrolyte imbalances. They're the result of poor training, and not training for race-day conditions.

Lipolysis- A fancy word for fat burning. If you can utilize fat more than carbs, and perform for long periods of time with no carbs, then you teach your body to use fat, not carbs. There's little evidence that a high-fat diet can make you burn more fat. Training your body to use fat is what's more important, not the percentage of fat in your diet.

Acclimatization- One of the most interesting points in the article was how important it is to acclimatize. It's like acclimatizing to altitude. At first, your performance suffers. After a week, you feel fine. Heat is the same way. After just one week, time to exhaustion doubles! If you're going to run in a hot climate, then train in a hot climate. Doing some training in the late afternoon. Don't forget the sunscreen. When you acclimatize, you work at a lower heart rate, your metabolic rate decreases and you use more fat, not carbs. Your body releases less sodium in sweat. This is when a heart rate monitor can actually help you. You can monitor your adaptation to extreme environments, and you can make sure you don't cross a critical threshold. Heart rate monitors are a topic for a different post.

Nutrition- Drink water, but also consume some electrolytes, especially sodium. Do not drink Gatorade. Gatorade has a lot more water than sodium, so drinking Gatorade will actually dilute your sodium concentration even more. But you must eat/drink on race day what your ate/drank during your training

Clothing- Wear a sun visor with no protection on the top of the head. You want to protect your eyes and avoid sunburn, but you need to release the heat from your head. While the majority of your heat does not leave from your head (another exercise myth), a good portion of it does. Also consider wearing white clothes, or a wet long-sleeved t-shirt.

That's heat management 101. I also recommend that you not train between 10-2, as this is when UVA rays are most prevalent. Refer to my post on vitamin D for more information about that. But if you do plan to race in a hot environment, then you need to plan some of your workouts for the late afternoon. Heat does not kill. Poor management of heat, improper training, and lack of preparation do.

Kevin