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Running in the heat: PREPARE, ADAPT AND SURVIVE


The summer months arrive and the days when the temperatures easily reach more than 30 ° C with a hot sun, are not rare. Heat exhaustion, heat stroke or other heat-related problems can occur quickly and could even become fatal. Your approach to practice or competition in endurance sports such as Trail-running, Marathons, Triathlons, Cycling, etc., must change to take into account the real dangers posed by this heat. Knowing how to prepare and adapt properly is a vital knowledge for any athlete practicing an endurance sport. He can even save your life.

Here is a general guide and some basic explanations on the best way to prepare and adapt your practices:



Before and during and after exercise, rehydration should be your main priority to maintain fluid balance, especially in hot, humid summer months. Therefore, your best bet would be a hydrating sports drink diluted with water. Because of the high sugar content of most sports drinks, the liquid is not easily absorbed into the bloodstream. By mixing half / half of the water and a sports drink, you provide your body with the best combination of electrolyte replacement and immediate absorption. Products are also available that contain pure electrolyte concentrations that you simply add to the water, such as pellets ZERO of the brand HIGH5, the Regeneration sticks  the STIMIUM brand or the capsules from the GU Nutrition brand. 

BEFORE: Many runners think of rehydrating after their run and some use water or sports drinks during the race, but it is equally important to be well hydrated before running. As a general rule, drinking 500 ml of water two hours before your race will ensure good hydration levels and give water time to get through your system so you do not have to pit pitstarts during your race.

WHILE: Hydration during your race depends on the temperature and the length of your race. Do not wait until you feel thirsty before drinking. If you are thirsty, it means that you have already lost too much fluid. Also, as you get older, your thirst mechanism is not as effective and your body may be in the early stage of dehydration and you may not even feel thirsty.

For 45 to 60 first minutes, water is sufficient. After 60 minutes, you will need to start using a sports drink or to complete with a sport gel or salty food like pretzels. After 60 minutes (and sometimes earlier if it's really hot and you're sweating a lot), you start to deplete essential electrolytes (i.e., Sodium, potassium, etc.). Sodium is needed for your body to absorb the fluids you ingest. Have you ever experienced a "ripple effect" late in a race? This is most likely because your body is depleted of sodium and therefore cannot absorb the fluids you drink. You swallow liquids, they stay in your stomach, but you don't absorb them and it "laps". Depleted potassium levels can also increase your chances of experiencing muscle cramps.

AFTER: after finishing your run, water or a diluted sports drink is not the best choice for your recovery needs. Water and diluted drinks do not contain enough sugars and electrolytes that your body needs to get back into balance. In addition, because water or very dilute drinks are so rapidly absorbed, the consumption of large amounts leads to an increase in plasma volume (in non-technical terms, it means that your body is now saturated with water or diluted). This rapid absorption leads to an additional imbalance of electrolytes and frequent bathroom shutdowns, which will only increase fluid loss and decrease your desire to drink.

Your best action after training is a recovery drink that contains a good amount of sugars and electrolytes that will speed up your recovery process and stay with you a little longer ;-).



Dehydration occurs when your body loses too much fluid. This can happen when you stop drinking water or lose large amounts of fluid through diarrhea, vomiting, sweating, or exercising. Not drinking enough fluids can cause muscle cramps. When you are dehydrated, you may deteriorate, have nausea and / or vomiting, heart palpitations and / or dizziness.

Runners, cyclists and other endurance athletes should also be aware of signs of severe dehydration, such as heat exhaustion and heat stroke. This not only for yourself, but you will be able to identify the symptoms if another runner suffers heat problems.

The effects of stress in heat can take many forms.

What to do depends on how you feel:

Heat cramps

  • Cause: Dehydration causes electrolyte imbalance
  • Symptoms of the disease: serious or severe abdominal muscle cramps
  • Treatment: Restore salt with foods or drinks containing sodium

 Fainting heat

  • Cause: Often caused by a sudden stop that interrupts the blood flow from the legs to the brain
  • Symptoms of the disease: fainting
  • Treatment: after the fall, raise the legs and pelvis to help restore blood flow to the brain

 Heat exhaustion

  • Cause: Dehydration causes electrolyte imbalance
  • Symptoms of the disease: basal body temperature of 38,5 ° C to 40 ° C, headache, fatigue, heavy perspiration, nausea, moist skin.
  • Treatment: Rest and apply a cold pack on the head / neck; Also restores the balance of salt with sodium foods and drinks


  • Cause: excessive intake of water dilutes blood-sodium levels; Usually occurs after four hours or more of effort.
  • Symptoms of the disease: headaches, disorientation, muscle contractions
  • Treatment: emergency medical treatment is needed; Hydration in any form can be fatal


  • Cause: Extreme stress and dehydration affect your body's ability to maintain optimal temperature
  • Symptoms of the disease: Body temperature of 40 ° C or higher, headache, nausea, vomiting, rapid pulse, disorientation
  • TreatmentEmergency medical treatment is required for immediate immersion of ice water and intravenous infusion.



Cover your body: Wear light clothing with air vents. Consider wearing a cap, or better yet, sunglasses to reduce heat build-up in your head. Before you go, apply a broad spectrum, sweat resistant sunscreen of SPF 30 or higher to all exposed skin.

Lower your expectations: accept the fact that the race will probably be more difficult than expected. Start slower than expected, and make sure you finish to reach your main goal. Led by time and effort rather than by distance and pace.

Water yourself: On a long hot run, in the refreshments, take a cup of water to drink, and another to pour over your head. If necessary, slow down in refueling to be sure you have enough to drink. If possible, bring an extra bottle of water. Do not drink this one. Instead, during the race, periodically pour some water on your head.

Run early: there is no ideal time to run in summer. But the first hours of the morning offer the lowest temperatures and the strongest sun hours (even if the humidity is at its highest level).


Legal warning
Before starting a new diet and exercise program, check with your doctor and review any exercise and / or diet with them before starting.
All information is generalized, presented for informational purposes only and not for medical advice. They are presented "as is" without warranty of any kind whatsoever.Readers are kindly requested not to rely on this information as medical advice and to consult a medical, food, physical or professional professional qualified for their specific needs. . uses cookies to provide the best user experience. Please accept cookies to continue exploring our site
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