We grabbed your attention with images of our Coast Guard K-9s and station mascots to play on the title of our post, but now that you are here you might as well read the important information below!
Written by Lt. Cmdr. Joseph Johnson
The signs and symptoms that accompany heat strain are well-known; sweating, increased heart rate, dilation of arterioles, etc. Rather than describe the negative outcomes associated with excessive heat strain, (e.g. heat stroke, heat exhaustion, syncope, etc.) I’ll explain how to manage heat stress on the job or at home in order to avoid the obvious signs of heat disorder.
Understanding Heat Stress
Heat stress is defined as the burden or load of heat that must be dissipated if the body is to remain in thermal equilibrium. To understand how to keep your heat stress in check you need to know that there are only two ways to monitor your physiological response to heat: heart rate and core body temperature. The details for how to use one or both of those parameters to monitor heat stress is beyond the scope of this article, but suffice to say if you intend to write a heat stress management plan for your job site or recreational activity (coaches, scouts, etc.) you need to take a hard look at incorporating one of those thresholds. If your plan is to monitor heat strain solely on visual observation, you may run the risk of waiting until you or someone else is ill before taking action.
The steps outlined below will help you avoid that kind of blunder.
Practical Considerations to Prevent Heat Strain Disorders or Injury
The National Weather Service Heat Index Advisory describes a heat index of 90° to 105°F as a time to use extreme caution. When you step outside on a hot/humid day you immediately recognize the oppressively heat and/or humidity. Heat disorders or injury typically occur when people over estimate their hydration status, under estimate the metabolic demands of the work they are doing, or under estimate the cumulative effects of heat stress.
The greatest physiological defense against excess heat is the cooling provided by the evaporation of sweat. Adults sweat up to 1 liter per hour if work output is sufficient. Remember—it’s not how much you sweat, but how much sweat evaporates off the skin that counts. Conversely, you can exploit clothing to help wick moisture. For instance, I use a long-sleeve swim shirt to provide sun protection, but that material is perfect for wetting down while I trim the trees on a hot day.
Regardless of how much you sweat, if you are working too hard –for instance running in a heat index of 101F (bad idea) — your body cannot dissipate heat quick enough to prevent injury if you keep running long enough. Therefore, if you are in a situation where you do not have access to a conditioned space or cooling station, your only option is to reduce your workload.
Frequent rest breaks in the shade or in a cool place are necessary for recovery and for opportunities to hydrate. According to the CDC, moderate activities in moderately hot conditions require an adult to drink 1 cup of water every 15 to 20 minutes. Be aware that cool locations or cool water submersion may blunt thirst. This is especially important for children.
It is also important to understand that heat stress is cumulative. For instance, you should be wary of plans for a teen’s sports team to have two-a-day practice in hot and/or humid weather. I recommend that parents read the American Academy of Pediatrics Policy Statement—Climatic Heat Stress and Exercising Children and Adolescents that discusses key exertion and heat-illness factors.
Some quick tips:
• Absorbent clothing can be soaked in water to aid cooling.
• Wear breathable light-colored clothing.
• Plan your activity to include frequent breaks.
• When your day is done eat foods high in potassium like potatoes, sweet potatoes, tomatoes, dried apricots, or tomato juice to aid electrolyte recover.
• Alcohol can have a detrimental impact on hydration status; be careful to not over consume the night before exposure to heat stress.
For more information, please visit Health, Safety, and Work-Life or leave a comment below.