Hydration and Acclimatization Amidst Season Change

As the seasons change so does the environment and the ambient (surrounding) temperatures. In the north we experience dramatic seasonal swings and with the first really warm days typically we start seeing the first sun burns and we see increased occurrences of dehydration, and heat related illness. Dehydration is important because it can lead to heat exhaustion, heat stroke and in some cases can be fatal. However we can go overboard with the water consumption and develop hyponatremia. This condition caused by over consumption of water can also be fatal. So what to do?

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Lets Talk About Sweat

Let’s talk about sweat! Sweat is a fun little substance our body makes to cool us down through the process of evaporation but also helps us expel toxins. There are some interesting things to know about sweat. For example:

• Sweat is more than water. It typically contains salt, potassium, calcium, magnesium (electrolytes) as well as some toxins i.e. lactate, ammonia, and urea
  
• Sweat rates change with acclimatization.
  
• Density and proportions of electrolytes and metabolites in sweat changes with acclimatization.
  
• The absence of sweat on a hot day is a sign of heat stroke
  
• Sweat is less effective at cooling us off as relative humidity rises (amount of water in the air as compared to the amount it can hold)
  
• Aired climates where humidity is low can allow the body to easily sweat and evaporate making cooling off more efficient but it can also allow the sweating to go unnoticed allowing us to dehydrate more quickly
  
  

What is Dehydration?

Dehydration is typically defined as losing more water than you bring in but is best characterized by the body’s impairment to carry out normal bodily processes. This definition is not especially helpful to people so we will discuss identifying dehydration, as well how much you should be consuming. Keep in mind properly hydrating is not the only strategy to keeping people safe in the heat, however it is the one we will be focusing on today. 

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Dehydration Symptoms

Thirst is often the first noticed symptom of being dehydrated. That’s right… If you feel thirsty, you’re already dehydrated. Other early symptoms are: dry mouth, infrequent urination, low urine volume, and dark urine (although this is often chronic dehydration). When the body reaches 2% dehydration symptoms will likely include one or more of the following: fatigue, headache, nausea, dizziness, and impaired physical and cognitive performance. Dehydration is said to be severe and likely require medical intervention when body water loss reaches 10 or more percent, symptoms may include any of the symptoms above as well as: lack or reduction in sweating, sunken eyes, low blood pressure, fever, delirium, unconsciousness, dry skin, and increased heart rate. There are approximately 500,000 dehydration hospitalizations per year resulting in about 10,000 deaths.

Hydration Under Normal Conditions

As a general rule and under normal conditions we should consume water in a quantity that is approximately half our body weight in ounces.

An example of proper water consumption (again under normal conditions) can be illustrated as such: if you weigh 180 pounds you should drink about 90 ounces of water. If you are outside intermittently in the summer this amount of water intake will likely remain unchanged. Days you’re out in the heat for prolonged periods of time the  water intake will need to increase. 

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Hydration In a Hot Environment

Hydration in a hot environment is different from standard hydration as sweat rates increase. The CDC recommends 24-32 ounces of water per hour in a hot environment. If you want a more precise recommendation you can perform the following experiment. Assuming we are starting in a hydrated state, begin by weighing yourself without clothes on. Get dressed then enter the hot environment and perform physical activity at about the intensity you normally would (and make sure someone knows you’re doing this). Do this for 1 hour. Return back to where you weighed yourself. Take your clothes off and re-weigh yourself (this is important because your clothes will absorb sweat). You will likely see a weight loss of 1-2 pounds. Unfortunately this is not fat weight. It’s water weight. Now you know how much water per hour you need to consume in order to maintain your hydration.

Drinking Too Much Water Can Be Fatal

It is important to point out that one can over hydrate. If we consume too much water we can develop hyponatremia which can be fatal. Hyponatremia is a condition where too much water has been consumed and the electrolyte fluid ratios are thrown out of balance. Electrolytes such as salt, potassium, and calcium are important to transferring electrical signals in the body. If our electrolytes are diluted our body can’t function properly and in severe cases can shut down completely, resulting in death.

This condition can be easily avoided by ensuring you consume enough electrolytes throughout the day. In most cases the electrolytes we get in our everyday meals are adequate. In severe heat  it may be advisable to lightly salt your food and/or alternate between electrolyte/sports drinks and water. It is unlikely you need every drink to be an electrolyte/sports drink so don’t go overboard. Be aware that typically electrolyte/sport drinks are high in sugar. One popular approach is to drink one electrolyte/sport drink for every two drinks of water. If you do this you will likely have the appropriate electrolytes to function optimally and have nothing to worry about. 

Acclimatization Safety

The role of acclimatization and its impact on hydration and heat borne illnesses can not be overstated. It takes the human body approximately 10 days of working in the heat to acclimatize completely. When acclimatization is complete you’ll notice earlier onset of sweat in the hot environment, increased sweat volume (amount), slowing of the heart rate (initially heat will cause a boost in heart rate), and a less noticeable reduction in electrolyte loss in sweat. It is also highly advisable to acclimate to the heat slowly. For example, an easy and safe way to acclimate is to spend 20% of your waking hours in the heat, then increase it by 20% each day. By day 5 you will have spent all your waking hours in the heat. You won’t be completely acclimated but you will be well on your way.

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A Word on Heat Exhaustion and Heat Stroke

Lastly, a note on heat exhaustion and heat stroke. Neither of these conditions are a laughing matter. If either of these are suspected, seek medical attention immediately. Below are the symptoms and actions to take:

• Heat Exhaustion symptoms: headache, nausea, dizziness, weakness, irritability, thirst, heavy sweating, increased body temperature, decreased/ceased urination
  
  • Action: Get to a hospital/call 911, remove unnecessary articles of clothing, sip water, use cold compress or moisten skin (arms, legs, neck, face, forehead etc
    

Heat Stroke symptoms: slurred speech, confusion, hot/dry skin or profuse sweating, high body temperature, seizure, coma/loss of consciousness
Action: Call 911, remove outer clothing, ice bath/soak in cold water, wet wash clothes, 

Summary

Dehydration and heat borne illnesses are easily preventable by ensuring that you acclimatize properly, consume adequate water and electrolytes and that you are prepared for the environment to which you’ll be exposed. Remember as a general rule you should consume approximately half your body weight in ounces in water under normal conditions. When in a hot environment you will likely need 24-32 ounces each hour. If you feel thirsty you’re already dehydrated. You should expect about 10 days to fully acclimate to the heat. Be aware of the symptoms of dehydration and heat borne illness and take action quickly if you’re presented with symptoms, especially if you’re in a hot environment.