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We’ve been lucky to have had a fairly mild summer so far, but there still have been days where the mercury has risen, making strenuous activity uncomfortable.  But at what point does it become dangerous?

The recent death of a University of Maryland football player during training shows that we don’t need to be in record setting territory for a tragic incident to occur.  While the specifics of his death may never be released to the public, I would venture to guess that it was not heat or exercise alone that took his life.  Likely dehydration played a role.

There are races run through Death Valley, and our soldiers deployed to desert regions still conduct physical training in high heat environments, and they seem to be all right once they acclimate to the area.  We don’t see triple digit temperatures much here, so what do we have to worry about?  Humidity.

Humidity is the one factor that really makes working out in the heat difficult.  The more humid it is, the harder it is for sweat to evaporate, and the tougher it is for your body to regulate its temperature.

During my time in the Army, we as leaders were constantly monitoring and factoring in weather conditions in our training to keep our soldiers as safe as possible.  We had a device called a wet bulb that measured temperature and humidity, and based on the readings, we determined what heat category we fell into.  Each heat category specified certain periods of work and rest and modifications to the uniform, such as untucking pants from boots, to help prevent heat casualties.

Take a look at this heat index chart to see what the temperature is equivalent to when humidity is factored in, and also the color-coded hazard categories.


Knowing that you are entering into a hazardous heat index area is just part of what you should be doing to stay safe when working out in the heat.  Proper hydration is key.  That means drinking water well before your workout.  It is recommended to drink at least 16-20 ounces of water 1-2 hours before your workout.  Your body needs this time to distribute the water throughout the body.  Chugging this much water right before a workout is going to make you sick and will not allow your body enough time to make use of it.

You also may need to drink during a workout.  The recommended rate is to drink 8 ounces of water every 15 minutes of your workout.

The guidelines for post-workout hydration can vary.  One recommendation I found was to drink 24 ounces of water for every pound lost during your workout.  This means you would have to weigh yourself before and after the session.  I think as long as you are drinking your bodyweight in ounces throughout the day, you should be in good shape.  To help replenish lost nutrients, stay away from the sugar laden sports drinks and instead drink coconut water or add a few pinches of salt to your water bottle.  Stay away from coffee and sodas as these can dehydrate you.

Studies have shown that just a 2% loss in body fluid translates to a 25% decrease in performance. Another study of runners showed that they tended to underestimate their fluid losses and overestimate the amount of fluids they were taking in, so keep good tabs on what you are losing and what you are drinking to replace it.


Aside from keeping up with your water intake, there are other strategies for safely working out in the heat.  If possible, workout during the cooler times of the day, before 10AM or after 2PM. Wear loose fitting or moisture wicking clothing.  Stay out of direct sunlight if possible.

Be aware of your body’s response to the heat, specifically, symptoms like dizziness, headache, hot dry skin that is flushed but not sweaty, high body temperature, or rapid heart rate that does not return to normal after exercise.  These may be signs of heat stroke or heat exhaustion.   Also know that if you have experienced a prior heat-related injury such as heat exhaustion or heat stroke, you are more likely to experience another heat related injury.  So, take extra precautions if you are a prior heat casualty and are working out when it’s hot outside.

In Maryland, we rarely see heat and humidity conditions that can’t be overcome by proper hydration strategies.  Keep up with your fluid intake and you should be able to workout in almost any heat category we are likely to encounter here.  

That being said, each of our bodies are different, and various factors like age, medications we are taking, etc., can affect how well we are able to regulate our body’s temperature while working out.  Monitor yourself and your fellow athletes in the Box for signs that you or they are not feeling normal. No workout is worth getting hurt over. If something doesn’t feel right, tell a coach and take a breather.  Hopefully by being aware of each other and following these guidelines, we can make sure we all can workout safely no matter what the temperature.