As we get into the middle of summer, many races involve running in severely hot weather. The most experienced runners use several tricks to deal with this, which are most evident at two Californian races renowned for their searing heat—Western States 100 and Badwater 135. Temperatures in these events are usually in excess of 100 degrees F, so runners have to be experts at keeping cool.
First, it’s important to understand the body’s main method of avoiding overheating—perspiration.
How Does The Body Cool Itself?
When the ambient temperature is above body temperature, heat transfers into the body rather than out. Since there must be a net outward heat transfer to avoid overheating, the body relies on the evaporation of sweat from the skin and the evaporative cooling from exhaled moisture. The cooling effect comes from the vaporization of water. If part of a liquid evaporates, it cools the liquid remaining behind because it must extract the necessary heat of vaporization from that liquid in order to change into a gas.
Training in the heat causes the body to adapt to improve the effectiveness of sweating, including increasing the amount of blood plasma, allowing an increase in your sweat rate while making sweat less salty. However, when the temperatures are extremely high and your running generates additional heat, it becomes important to help your body keep cool externally. This also applies when sweat is unable to evaporate in humid conditions.
Issues With Humidity
The principles differ for humid races because sweating is much less effective. The more humid it is, the less your sweat will evaporate, so it can have little or no cooling benefit. More drastic measures are needed.
Tips For Cooling Yourself In Addition To Sweating, As Evidenced By Ws100 And Bw135
First, bear in mind that drinking does little to cool the body (see chapter three of Waterlogged by Professor Tim Noakes), and that external cooling is by far the most effective method. Here are tried and tested methods of keeping yourself cool, some of which are easier to undertake with a crew at a race.
The most effective way to cool your body is by applying cold substances, typically ice water and ice, externally to your body. In particular your brain needs to be kept cool, so pouring cold water over your head and neck is very effective, but short-lived. A great way to keep that cooling effect between aid stations is to put ice under a hat, in a bandana around the neck or in a sports bra (I’ve even known men to use the latter at BW135!). At aid stations, if you’re really getting hot, try to put ice against the arteries in your neck, under your arms and around your groin—this will cool the blood going to the extremities of your body.
Cover your skin with white or light fabrics. Not only does this minimize sunburn, it stops the sun baking your skin and raising your temperature. There’s a good reason that BW135 runners cover themselves up. It’s the same logic used by desert-dwelling tribes in the Middle East and the Sahara Desert. To get a cooling benefit from these fabrics, keep them wet, ideally dousing with cold water whenever possible. Adjust your effort level if you start to overheat, since the harder you work, the more heat you generate. This can be especially important when going uphill in the sun, since your effort is likely to increase and raise your internal body temperature. Slowing down will also make it easier to eat, drink and digest, keeping your energy levels up through the race and minimizing stomach issues.
Take advantage of any shade along the course, even if it means running on the outside of a curve. If you start to feel dizzy and really hot, then consider stopping in the shade brief ly to combine the cooler temperature externally with generating less heat by stopping.