The sun affects our body’s internal chemistry in two main ways. First it causes loss of fluids and electrolytes, second it induces free radical damage.
You know the expression that your blood thins in a hot climate? When I was a kid we moved to Arizona from Minnesota. I was told countless times that my blood would thin out because of the warm weather. It made me crazy because I was sure it was a fallacy, but as I studied physiology I learned it was exactly true. One of the adaptations our body makes to a hot climate is to carry a higher percent of fluid in our blood stream.
Even with these adaptations, we lose tons of fluid in a dry climate. Most of which is carried off in our breath. We also sweat much more than we’re aware of when the air is dry. It evaporates so fast we don’t even realize that we’re losing water. Sweat cools our bodies through evaporation. Sweat is a mix of minerals and water. The more time we spend in the heat, the fewer minerals we give off, making our sweat less salty.
The difficulty in staying hydrated is that we cannot absorb fluid as fast as we can lose fluid. You’ve heard that you should drink while you’re exercising, but the real trick is to drink before and after as well! The most fluid that an adult human can assimilate is 24-28 ounces per hour. That’s it! If you drink more than that you’ll only overfill your stomach and dilute your remaining electrolytes even further.
Do you want to find out how much fluid you lose in the heat? This is easy – weigh yourself before and after your activity. You can easily lose several pounds of weight even if you drink water while you’re out. Too bad fat doesn’t go away that easily! The next time you go outside for yard work or a game of golf, test your hydration level. Get the water you plan to drink while you’re out and hold it in your hand, jump on the scale in your clothes before going out and after you’re done, and be sure to hold that empty water bottle in your hand for the second weigh-in. The weight difference is your fluid loss. If you’re a 130 pound woman who weights 138 with clothes and water bottle but come back at 134, you just lost 3% of your body’s fluids and have gone into significant dehydration.
When we lose 2% of our body’s fluids we began to enter into dehydration. At this level, the following symptoms are common:
· Sensation of thirst
· Loss of Appetite
· Skin Flushing
· Dark Colored Urine
· Dry Mouth
If you do this often you will elevate your risk of kidney stones, esophageal reflux disease, gall stones, constipation and muscle spasms.
Let’s say you really worked hard in the garden, got everything done and came back inside weighing 131. This would be 5% of the body’s fluids and you’d be feeling pretty lousy. You could expect the above symptoms to a worse degree and also:
· Increased heart rate
· Increased respiration
· Increased body temperature
· Decreased sweating
· Decreased urination
· Decreased thirst
· Extreme fatigue
· Muscle cramps
· Tingling of the limbs
This stage is also called heat exhaustion and can lead to symptoms of fatigue persisting for several days or more, often with persistent muscle cramps. Your brain is significantly swollen from the salt in your blood being too low. This can cause a decrease in reasoning and rational thinking. If you live alone this is the time to call someone over to keep an eye on you and help out. You may not be thinking clearly enough to do the obvious things like cool off, drink fluids and rest as you need to. The other difference is that now the body’s mechanisms for dealing with the heat can no longer effectively control our temperature.
If you get to this point, it is not a bad idea to drop by our clinic or your neighborhood urgent care for some intravenous fluids and electrolytes, IV’s take less time getting these vital nutrients and fluid into the blood.
If your fluid loss gets much higher than 5%, you really can’t control your body temperature well at all and you may end up with heat stroke.
We define heat stroke as:
· Oral temperature over 103
· Red, hot, and dry skin (no sweating)
· Rapid, thready pulse
· Unconsciousness or coma
Exertional heat stroke is from activity in heat, Non-exertional heat stroke is from just being in the heat. Whichever it is from, this is the time to call 911l. The body becomes so parched things could shut down quickly.
OK, so to make sure none of us ever get to heat stroke or exhaustion we have to be realistic about our heat exposure! Avoid direct sun exposure, use barriers as mentioned in the article on sunscreen and maintain a healthy fluid/electrolyte balance.
Fluids = water. Gatorade and most sports beverages are water + lots of sugar + trivial amounts of electrolytes. Soda, juice, tea, coffee and alcohol make you lose more fluids than they give you. Since we can’t absorb much when we’re out in the heat, pre-hydration is critical. How do you know if you’re hydrated? Here’s another easy test. Go pee and look. What color is it? Any color that isn’t just about the same as water means you’re not drinking enough water.
What about the electrolytes? They vary more than water based upon how used to the heat you are, how hard you’re playing/working and your current health. The main electrolytes to be concerned with include sodium, potassium, magnesium and calcium.
Sodium can be tricky. A high salt diet makes us waste it more readily in our sweat and urine. You’re actually better off over time if you consume fewer than 5000 mg daily. Watch the labels; this is not a lot of salt. If you are currently consuming more than 5000 mg a day, you need to reduce your sodium intake, but be sure to decrease it gradually over the course of several weeks. Your taste buds will have time to adjust and your body will have a better chance adapting.
Potassium is in all produce. The top three sources are tomatoes, potatoes and bananas. Coconut water is a tasty, low sugar beverage rich in potassium. Good old V8 Juice is also a good source. Don’t bother with non-prescription potassium pills; they can’t legally contain enough potassium to be helpful since high doses can be harmful for some people.
Calcium is contained in broccoli, spinach, almonds, salmon, dairy foods, fortified OJ and fortified soy milk. Supplements are a good idea for most people.
Magnesium is in beans, nuts and leafy greens, yet it is hard to get enough without supplements. Cal/Mg combos are a handy way to get them both, make sure they contain vitamin D for absorption.
If you’re active in the heat for over 1/2 hour, it helps to consume some electrolytes during activity also. Most electrolyte products contain far too much sugar. Unless you’re continually maintaining a high heart rate like running or cycling for over 60 minutes, you can do fine without any calories.
I have found two mixtures of electrolytes w/o sugar that have good proportions of the full spectrum of electrolytes. Unfortunately I know of none that are routinely stocked in pharmacies or health food stores.
Hammer Nutrition makes a great product called Endurolytes. It comes in powdered form that you can add to water or in capsules that can be carried and taken as needed, like a modern version of salt tabs. Each scoop of the powder equals one of the capsules. Use between 2-5 servings per hour based on fluid loss. If you don’t cramp or lose more than 1% of your weight, you got it right. After trying scores of products, I swear by this one and use it on all my bike rides. We stock this, as do some bike shops and REI.
Allergy Research Group makes a product called Balanced Electrolyte Concentrate. This is the next best product I’ve found. This is a very concentrated electrolyte liquid that can be added to water, 1/2 tsp is enough for 16 ounces. We stock this as does The Natural Medicinary in Tempe.
Have a great time this summer! Stay properly hydrated and I promise you’ll be able to do more and recover better. Maybe you won’t even mind the heat as much!