The topic of running in extremely hot weather conditions has enjoyed a great deal of media attention during recent years. Participants are confronted with extreme heat during events, more and more often, like in the past at the marathons in Paris and Rotterdam. The likelihood of problems is greatest when it involves a sudden increase in temperature. Therefore, try to get used to the heat as much as possible. Naturally, a situation like this means that increased moisture is lost due to perspiration. Excessive perspiration results in dehydration and can lead to the following heat stress symptoms:
Painful contractions of skeletal muscles cause cramps, mostly in the calf muscle. This is due to extreme moisture loss, which disrupts the balance between the salts in the body’s cells (sodium, potassium, calcium).
A temporary, partial (fainting) or total loss of consciousness (collapse) is caused by the accumulation of blood in the lower extremities. This causes a drop in blood pressure and is followed by loss of consciousness. Individuals who spend long periods of time standing still in the heat like linesmen and onlookers are at risk for this symptom.
Symptoms of sunstroke (heat exhaustion) include extreme fatigue, dizziness, headache and skin that is soaking wet from perspiration. This is very hard on one’s heart and circulatory system. This is due to the fact that skin circulation is increased, in order to discharge heat, while the circulating volume is lower because of the moisture loss on account of perspiration.
Hyperthermia (heat stroke) is a life-threatening condition. When the heat and moisture loss persists, skin circulation drops in favour of central circulatory functions. One’s body temperature can then increase significantly. Symptoms include hot, dry skin, rapid pulse and irrational behaviour. It can sometimes even lead to convulsions and fatal damage to the nervous system and internal organs.
It is important to realise that you can reduce the health-related risks under exceptional weather conditions, by considering the following tips:
a) Perspiration must evaporate
Perspiration can evaporate easily if the clothing is made of light, breathable and loosely woven fabric, like functional running clothes, for example. A headband can help keep perspiration away from your eyes.
b) Sun protection
Ultraviolet (UV) rays, both UV-A and UV-B, can damage the eyes and can cause skin cancer. A cap will keep your head cool and protects your face and neck from sunburn. If the sun’s rays are too bright, then sunglasses or dark contact lenses are certainly no luxury. This is also better for your eyes in the long term. The skin’s best bet at protection is the use of sun protection cream with a good Sun Protection Factor (SPF). The recommendation for the Netherlands is to use at least a 10 to 12 SPF cream. Clothing is preferred over sun protection cream.
c) Drink regularly, even if you aren’t thirsty (but don’t drink too much)
Moisture and salt are the most important points of interest when it is hot out. Drinking purely water is not enough: this will lead to a poor salt ratio and could cause a shortage of sodium (cooking salt) in the blood. Alternate water with an isotonic sports drink: to which salt has been added. Drink enough, but don’t overdo it. Drinking too little and drinking too much are both life-threatening. To know how much you need, you can hop on a (digital) scale before and after training, once in a while. Try to drink a sufficient volume, so you won’t lose more than 2% of your bodyweight. Definitely don’t drink so much that you weigh more afterwards than you did before. This way you’ll also have a rough idea of what you will soon need to consume during the TCS Amsterdam Marathon. Drink 500 ml water (two large glasses) with your last meal, approximately 2 hours before the race. This will give you enough time to absorb the water, and also to get rid of any excess moisture before the start. Enjoy some extra salty foods when it is hot. Also use the water during the run to cool off your body. People tend to be affected by overheating more frequently than by dehydration. Dehydration does, however, lead to more rapid overheating. In other words, water on your body, sports drink in your mouth.
d) No salt tablets
Salt tablets were recommended in the past, on warm, hot race days. But don’t do this. Although it is correct that perspiration contains salt, the use of salt tablets is almost the same as drinking salty seawater when you are thirsty. It only makes the problem worse. Drink sufficient amounts of liquid and supplement the loss of salt by way of the natural salt in your food.
e) Adjust your tempo to the warm weather; even if you have trained well
Make a quiet start. Check your tempo; each second on a kilometre, for which you ran too fast at the start of the race, can lead to one minute’s loss per kilometre at the end. Run at your own tempo; do not increase your tempo and sprint in the last kilometre. It’s okay to take a break at any time, rest, cool down and continue.
f) Use the Medical team if you don’t feel well or if you drop out for any reason!
The first signs of heat stress include decreased coordination. This can take the form of uncoordinated running or stumbling, excessive perspiration or actually no perspiration at all, headache, goose bumps and shivering, nausea, dizziness, apathy (indifference) or actually aggressiveness and a slow loss of consciousness. If you notice one of these symptoms with yourself, stop running to prevent serious problems and seek assistance from a marshal who can call for a member of the medical team. If one of the team on duty notice any symptoms of heat stress, he or she will be entitled to pull you from the race and to guard you from serious problems.
g) Dress yourself as soon as possible after the race
h) Likelihood of a repeat occurrence
Individuals who experienced problems with heat in the past are at greater risk for repeated problems, and it is very sensible for them to keep sports activities in the sun to a minimum. Children, older people, sick people and people who are not quite as fit, are at greater risk for heat stress symptoms. It is best if these individuals avoid situations involving extreme and long-term heat.