Blog Search

District H Crossfit Blog : Wait…. What’s the temperature?! by Coach Ray

By: 0

Wait…. What’s the temperature?!

In this blog we will cover training in intense heat and humidity. Having a better understanding of how our body reacts, counter measures, and treatments will allow us to be smarter athletes. You may have heard me say; “there is a fine line between tough and stupid”, and for heat illnesses it is especially true. In no way do I want you to shy away from pushing yourself, but you need to be in tune with your body.

Your Body’s Reaction to Training in Hot/Humid Temperature

Normal body temperature is generally accepted as 98.6 degrees Fahrenheit with small fluctuations up and down. However extreme change in either direction can have detrimental effects to your entire body. As we approach the hot humid summer of Houston we need to approach training in smart way.

Our body is amazing and has a built in thermostat that controls the body’s responses to heat. The primary mechanisms that cool our body are convection (wind), conduction (physical touch), radiation, and evaporation. In essence are body is continually regulating temperature based on environmental and internal conditions.

The most important of these measures during exercise is evaporation of sweat from our skin. Under dry conditions this mechanism can effectively cool our body but in the humidity of Houston our body has a tougher time cooling. The reason is the humidity; if water vapor is saturating the air around us, our sweat we cannot effectively evaporate off our skin. That why we look like we just jumped into a pool after a workout.

Counter Measures: Acclimatization and Preparation


The great thing about our body is it can adapt to these conditions. Now we could take the unscientific approach and “suck it up” or we can be smart and ensure we are ready for the heat. I have participated in military operations in the Mojave Desert, Iraq, and Afghanistan, but the humid conditions of the Southern United States are by far the worst I have experienced.

The Marine Corps’ general rule is 14 days of acclimatization before allowing a Marine to participate in heavy exertional exercise, The National Athletic Trainers’ Association suggest 7-14 days, and the Wilderness Medical Society suggest 1-2 hours of training in the heat for at least 8 days.

District H Crossfit began the acclimatization process on May 9th, by exposing our clients to more uncovered running and increased aerobic strain as the days become hotter and muggier.  By the time “Murph” comes around we will be 21 days into our acclimatization period surpassing the previous recommendations mentioned and falling 1 day short of the Manual of Naval Preventive Medicine guidelines of 22 days for optimal acclimatization.


Acclimatization is not a silver bullet, so we must also prepare are body everyday. Alcohol, illicit drugs, and some supplements may increase are risk of heat susceptibility. So we must make smart nutrition choices and couple that with good recovery behavior.

Hydration should be continuous and should never involve what is referred to as “forced hydration”.  Typically you should be consuming small amount of water continuously throughout your day to avoid symptoms of dehydration. The US Navy and Marine Corps use urine color as an indication of hydration status. Clear lightly colored urine in large volumes will indicated a proper level of hydration, while dark colored urine, with strong smell, and low volume will indicate a need to consume fluids. Marines are recommended to begin hydration 24-48 hours before heavy physical training that will last for extended periods of time.

More is not better in terms of hydration. During exercise we may find a need to consume water, but excessive drinking can lead to a life threatening conditioning known as HYPONATREMIA, this condition is associated with the consumption of large amounts of hypotonic water creating a solute imbalance. This can lead to swelling especially around the brain severely increasing mortality.

The final recommendation’s are: (1) Avoid stimulates and diuretics, while research is not 100% conclusive on their effect during exercise, if you don’t normally take something don’t experiment with it during “Murph”. (2) Get a full night of restful sleep, Navy standard is 6 hours and National Athletic Trainers’ Association is 7 hours. So for District H Crossfit, lets call it a solid 8 hours of sleep to be at our best.

Heat Illnesses and Their Treatments

The following are some Exertional Heat Illnesses recognized by the National Athletic Trainers’ Association, Wilderness Medical Society, Navy, Army, and Marine Corps.

-Exercise Associated Muscle Cramps

One of the most common symptoms associated with exercise and can be a result of overload and fatigue or excessive fluid loss.  These cramps are common in the abdomen and could be a sign of “fluid and salt imbalance”.

For cramps due to fatigue, stretching and rest will be best. However if cramps are due to loss of fluids and sodium it will be necessary to ingest sodium-containing fluids and or food.

-Heat Syncope

Is described as a feeling of mild and brief faintness, dizziness, and low blood pressure. You may experience this before or after heavy exercise.

Treatment is relatively simple, move yourself into a shaded cool area, elevate legs, and sip water for rehydration.

-Heat Exhaustion

This where we begin seeing more extreme illnesses associated with intense exercise in the heat. Common symptoms will include intense fatigue, mild confusion, and dizziness.

Treatment will include removal of excessive clothing and gear. Moving to a shaded cool area and use of cold towels or icepacks to begin cooling the body.  Lay on your back with your feet elevated and slowly replace fluids.

*While I could not find a reference, we as Instructors in Marine Corps would continually check individual’s eyes for dilation and body for lack of sweat. At no time during exercise should you stop sweating.

-Exertional Heat Stroke

The most dangerous of the illnesses is heat stroke. Symptoms are extreme cognitive degradation and a core body temperature over 105 degrees Fahrenheit. Commonly a person experiencing heat stroke will collapse, as nervous system function is impaired.

Treatment must occur quickly to prevent severe damage to the body or possible mortality.  EMS (911) must and will be contacted immediately. The athlete will be immersed in cold water up to the neck in an attempt to lower body temperature to less that 102 degrees Fahrenheit. Cold water should be continually stirred in order to allow for heat to be drawn from the body quickly.  If an athlete’s core temperature does not drop, he or she must remain in cold water until emergency services arrive.

Final Thoughts

I’ve seen the most physically gifted Marines, Army Rangers, and Division 1 athletes all succumb to heat. If at anytime you feel conditions such as the ones describe let your coach know and even take a small break from the workout. Make smart nutrition choices and get sleep. Training in the heat can be risky but proper training and knowledge can greatly reduce the risks associated with it.