Heat: your worst nightmare?

As a runner I hate the heat, it makes me less sharp, more sluggish and it makes me run a lot slower. But some days heat is what you get and no matter how minimally you dress or how much water you drink your body cannot handle it. Then the question comes: what are the most important things you need to know about body temperature and how can you help your body cool down in exercise condition?

Working out definitely increases one’s body temperature. Even a run in colder conditions will raise your temperature but that is beneficial since it increases the blood flow to the working muscles. Usually, the body temperature falls down at rest time and that also depends on the ambient conditions: in the winter the drop will be significantly faster than in the summer. And that is the good thing about exercising in winter!

On the other side, summer can come with high temperatures and/or humidity. When you exercise in the heat your body needs to work harder. Bodily functions, such as sweating, shivering, dizziness, headache and blood volume decrease, occur when your body temperature rises too high. Sweating acts like a natural cooling system. But humidity adds extra pressure when the body tries to cool down because the sweat will not evaporate so efficiently.  That is why it is important to drink more water and replace the lost electrolytes as you sweat more. With drinking more water, you can maintain at a normal level the plasma in your blood. You could become dehydrated when sweating is too much and your performance will drop since the blood flow will focus more on the skin to help it cool down.  The heat will the heartbeat as well, but it will not affect everyone’s heartbeat in the same way. In some cases, people used to heat may see very little difference in heart rate or feel fewer side effects when exercising in the heat.

On average, at around 39 degrees Celsius, there is an obvious decrease in performance. The heart stroke zone is at 40 degrees Celsius when exhaustion and cramps in quadriceps, calves, and abdominals can occur. After this stage, there can be hyperthermia when the heat-regulating mechanisms of the body eventually become overwhelmed. Hyperthermia may come on suddenly, but it usually follows the untreated milder stages.  However, everyone reacts differently to heat and everyone can even have a different base body temperature to start from. Temperature readings vary depending on the device used so you need an accurate body temperature to determine if a fever is present or not. In the end, the question is how accurate are then the above numbers per individual?

As part of my Matterhorn Ultra training I planned a trail in the National Park the Veluwezoom. During the Veluwezoomtrail  I had my temperature taken after Manon said I am looking too pale and worn out after only 10km in the race. Normally in a road race feeding stations are increased in such warm days and runners are given extra means to cool their heads. But in a trail race, you need to be quite self-sufficient, so fewer water posts, less water,  and no sponges to cool yourself down unless you carry it with you. I had something close to 38 degrees Celsius measured in the ear where my normal body temperature is close to 36 measured in the armpit, and chicken skin or maybe shivers. Immediately I was required, by the medical team, to stop and don’t continue for the next 23km out of which 8km in the plain sun at a temperature of above 30 degrees. I was planning to do a walk-run and back off the pace as running slower means you generate less heat and rest a little before going further if they will have allowed me to go further. I also took some extra concentrated salts diluted in water, besides the electrolytes I had in my camelback. These extra salts were handed in by a friend just before the start and I took them although I thought I will not need them. There have been times when I felt worse during competition but still carried on. And this time it didn’t feel that I went too deep but everyone around looked worried about my condition. Unfortunately, it was not possible to run further. Whether this time was really required for me to stop I couldn’t say exactly, the medical team decided for me and I had to go back to the finish line in a different way than I hoped, not on my own two feet but by car. Don’t let me even start on the disappointment. They gave me a medal at the finish but I cannot say that was earned.

But, what else can we do than to learn from this? I started checking what steps to take and what can be done better so that doesn’t happen again.  Here is a list of points to take into account when running on a hot day:

• acclimatization, or getting your body used to run in the heat which can take up to 7-10 days by training in the same conditions as the competition (same speed, same air temperature, and same humidity or as close to it as possible)
• sipping cool water for less intense workouts and electrolytes for longer and intensive workouts and hydrating sufficiently.  Make sure the water or sports drinks are cool, but not too cold. Very cold drinks may cause stomach cramps. There are ways to determine what sufficiently hydrating means for you. First, measure yourself without clothes before and after a test run of 1 hour in desired atmospheric conditions. Then calculate the weight difference add to that the amount of water consumed and divide by 4 to determine the amount of fluid necessary every 15 minutes
• hydrate well the day before the race, and that means (as bad as it may sound): check your urine color, it is too dark it’s time to drink some more to a light-yellow urine
• training or race precooling using special cooling clothes
• eat salty food the day before and on the day of the race, then your body will retain more water
• dress appropriately for weather conditions in light moisture absorbing fabrics and light colors and cover your head when possible
• don’t forget the sunscreen

Additionally, you could approach your training/competitions with realistic expectations and also get enough sleep. Sleep disturbances also affect body temperature. Short sleep deprivation produces higher temperatures than normal. Running the same number of miles per week in the summer is harder than in the spring/autumn when the weather and temperatures are perfect for it.  Then, the night is slightly bigger so the rest period is also bigger.