Training – Training in the Heat


If you’re like me your racing calendar is just getting ramped up. And many of your “A” races are going to be hot and humid. Racing in dog days of summer can be fun and exciting but if you’re not prepared properly it can become life threatening. Running in the heat is not a new experience for many of us. Our bodies are well equipped to deal with the dissipation of heat generated by exercise. But what happens when all the planning, prevention, and listening to our bodies still isn’t enough and adjustments need to be made to get back on course quickly?  


Heat related illnesses occur when muscle-generated heat accumulates faster than heat dissipates via exhalation, sweating and skin blood flow. Heat production during intense exercise is 15-20 times greater than at rest, and can raise core body temperature by 1-C (1.8-F) every 5 min if no heat is removed from the body. Depletion of energy stores (glycogen) from muscle tissue occurs faster in hotter conditions, especially when athletes are not acclimatized to exercise in the heat. And fast depleting glycogen levels means a greater chance of bonking and slow down rate.

 There are several variables that affect heat exhaustion in athletes including duration and intensity of exercise, environmental conditions, and acclimatization to exercise-heat stress, level of fitness, hydration status, and personal factors like medications, supplements, sleep, and recent illness. Some lesser know factors that affect heat dissipation are, skin disease, sunburn, alcohol use, drug abuse, antidepressant medications, obesity, and a history of heat illness. Some over-the-counter drugs such as antibiotics and nutritional supplements can also increase the risk of heat related issues. So it’s worth asking your Doctor or Pharmacist about the heat effects of your medicine.

 Most physiological adaptations from training stress takes 3-6 weeks to actualize, but heat acclimation can begin within 10 to 14 days of exercise training in the heat.


Here are a few ways to get a jump on heat acclimation before your big race.

  1. Scheduling a 45-60min mid-day run 3-4 x/week in the heat starting 3-4weeks prior to your race. The run should be easy in the first week. Allowing your body to adjust to the heat. The second week as you begin to feel your body adjusting pick up the pace to race pace gradually over the run. The third week through-in a few 60 sec strides  to rev up the engine generating more heat, followed by race pace allowing the body time to adjust to the increased heat. The fourth week, take the pace back to an easy pace to assure a race taper week.
  2. Turn off your air-conditioning in your house and car. Acclimation doesn’t just happen on the training ground. Staying away from air-conditioned buildings and spaces will greatly increase your heat tolerance.
  3. After your hard training sessions sit in a sauna. Don’t forget to take your recovery drink and plenty of replacement fluids with you. Getting dehydrated is not a heat acclimation tool!


  1. Starting your race well hydrated. To insure you’re topped off to the gills it’s best to assure proper hydrating a week before your race during your race taper week. As your muscles begin to store more glucose due to less running your body will also store more water at a cellular level. Plan to consume your body weight in oz every day the week leading into your race. Your body will use this extra water to cool your core temp throughout the race.
  2. Proper fluid intake during a race. Exercise guidelines recommend consuming 16-20oz of fluid/hr. If you are exercising in temperatures greater then what your body is accustomed to, you’ll need more fluid/hr to offset the stress of a higher ambient temperature. But knowing how much more can often be confusing. A rule of thumb is to make sure your pee is clear to light yellow. If you have not peed in over 3hrs and/or your pee is dark in color it’s time to increase your hydration.
  3. Proper Electrolyte intake during a race. Electrolytes are necessary for you muscular, cardiac, nervous, and digestive systems to function optimally. There are many ways to ingest electrolytes, solid foods such as, watermelon, potato chips, PB&J, gels, as well as, commercial sport drinks and electrolyte tablets are all valid electrolyte replacement choices. If you are eating solid foods and or drinking a sports drink you are ingesting electrolytes. One is not better than another but most runners have a preference. Knowing how much to consume can be a bigger quandary. If you tend to be a salty sweater, noted by salt rings on clothing and face, and/or you frequently get muscle and/or digestive cramps you may need to increase your consumption. There are many debates as to how much is the right amount, the answer is an individual quest. And best answered by listening to your body’s signs and cues.
  4. Proper gear choice. Wear breathable, light color and light weight fabrics. Some high tech tees are great at wicking and drying but you’ll want to avoid these fabrics in a hot race. Instead use materials that will hold moisture and stay wet for extending periods. When air travels across wet material the effects are evaporative cooling. This cooling action will assist your skin in dissipating your core temperature. In our high tech world, cotton is often over looked as a valid gear choice. Check your clothing label and next time the temperatures soar choose a cotton tech blend and run your own experiment.
  5. Skin wetting. Keeping your skin wet will allow your body’s core temperature to dissipate easily. And a cooler core translates to a faster pace with less energy expenditure.

 Try these race day tactics to keep you cool:

  1. Use water crossing to dip a handkerchief, dunk your body, head or hat .
  2. Carry an extra water bottle to dowse your neck and head. Note: you will need to use extra lubrication in areas that are susceptible to friction. I carry a small tube of Vaseline with me for quick reapplication.
  3.  Aid station Ice. Extra ice in your water bottles will not only cool your core with chilled water but holding cold bottles will also assist in lowering your core temperature. Shorts, bras, hats or a tucked shirt are all great away to store ice. As the ice melts you will continue to benefit from skin wetting.
  4. Wear a coolie or neck gaiter. I prefer the Kafka neck gaiters. The night before my race fill a gallon baggie with ice and water and immerse two neck gaiters in the water. By morning they are swollen with icy cold water.  Starting with a cool neck gaiter will assure that you don’t get over heated when the sun rises and the race is heating up. Remember to rotate the gaiter every 30min to get the full cooling effect. If the race is longer than 5hrs. Exchange the gaiter for a fresh one half way through the day in a longer race.


The symptoms and signs of heat related illness are often nonspecific and include disorientation, confusion, dizziness, irrational or unusual behavior, inappropriate comments, irritability, headache, inability to walk a straight line, loss of balance and muscle function resulting in collapse, profound fatigue, hyperventilation, vomiting, diarrhea, delirium, seizures, or coma. Thus, any change of personality or performance should trigger an assessment for heat related illness, especially in hot-humid conditions. The problem with this list of symptoms is that each one can be caused by the act of running an ultra race. The key is these symptoms are related and if you have two or more then assessment is imperative.


What if it just isn’t your day and despite all your heat training and race strategies you find yourself over heating? Cooling should be initiated and, if there are no other life-threatening complications, completed on-site prior to evacuation to the hospital emergency department. Athletes who rapidly become lucid during cooling usually have the best prognosis. The most rapid whole body cooling aid is ice water immersion therapy. Use aggressive combination of rapidly rotating ice water-soaked towels to the head, trunk and extremities and ice packs to the neck, auxiliary and groin area, for the quickest and effect cooling method. 

Cindy Stonesmith ACSM HFS, is a Running Endurance Coach with Ultrarunner Training. You’ll find her most days training in the foothills of Boulder Colorado. 

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