It’s summer! The days are longer, the weather is warmer, and the children are out of school. We all want to play more in the summer, taking advantage of the longer days and nicer weather. With our coastline and mountains, San Diego is a mecca for outdoor activity. Surfing, swimming, inline skating, running, cycling, mountain biking, rock climbing and a wide variety of team sports are the tip of the iceberg for our summer activities.

We are all taught to make sure we drink enough water during exercise. Many health care providers recommend drinking at least eight glasses of water per day and more during the summer or while exercising. What is not mentioned is that drinking much more than this can dilute essential minerals and electrolytes, which can cause a whole host of problems. I learned this first hand while on a bike tour of the Midwest during one of the most severe heat waves Missouri has seen in June! I found myself drinking almost 3 gallons of water a day to keep from thirst, which filled my belly so much that it was hard to eat enough calories to sustain 70 miles a day on the bike. Even eating salty snacks, salting my food more than usual, and taking double doses of my usual potassium, multimineral, and calcium supplements were barely keeping me up with electrolytes. Several people on the trip spent an afternoon in the ER for intravenous Ringer’s solution after suffering severe heat exhaustion and electrolyte depletion. This type of emergency can be easily avoided if you pay attention to your electrolytes in addition to your fluid intake.

What are electrolytes and why do we need them?

In chemistry, each atom has a certain number of protons (positively charged) and electrons (negatively charged). A stable atom has the same number of protons and electrons and has no electrical charge. An ion is an atom that has an odd number of protons and electrons, giving it a positive or negative electrical charge. An electrolyte is any substance containing free ions that behaves as a conductive medium for electricity.

In physiology, the primary ions of electrolytes are sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), and chloride (Cl−). The plus (+) and minus (-) electrical charge symbols indicate that the substance in question is ionic in nature and has an unbalanced distribution of electrons.

Both muscles and nerves are considered electrical tissues. Muscles and nerves are activated by electrolytic activity between the interstitial fluid (fluid between cells) and the intercellular fluid (fluid inside cells). Electrolytes can enter or leave a cell through the cell membrane and are required for a variety of cellular functions. For example, muscle contraction depends on the presence of calcium (Ca2+), sodium (Na+), and potassium (K+). Without sufficient levels of these key electrolytes, muscle weakness or severe muscle contractions can occur.

Electrolyte balance is maintained by ingesting substances that contain electrolytes and is regulated by both hormones and the kidneys. go back up

What electrolytes do we need?

Sodium

While sodium gets a bad rap from people concerned about blood pressure, it’s actually required for a variety of cellular functions and we can’t live without it. A human being requires approximately 500 mg of sodium per day for basic physiological functions. Sodium is one of the minerals necessary for nerve impulses to occur (nerve impulses facilitate every message from the brain to our muscles and internal organs). It is also important to maintain adequate blood volume.

For most of us, the problem with sodium is overconsumption, not underconsumption. Most processed foods contain exorbitant amounts of sodium, so it’s easy to consume much more than 500 mg/day. Consuming large amounts of sodium can become problematic for people with kidney problems or high blood pressure.

When we exercise on hot days, thirst often leads us to drink much more water than we normally would. This is good up to a point: once you’re thirsty, you’re already dehydrated. But drinking too much water can lead to water intoxication or hyponatremia (low blood sodium levels). Symptoms of sodium imbalance include headache, malaise, nausea, and vomiting. When levels drop below a certain point, hyponatremia can be life-threatening.

almond et al. (1) found hyponatremia in up to 13% of runners in a recent Boston marathon, with life-threatening hyponatremia in 0.6%. Runners at highest risk of severe water intoxication had moderate weight gain during the race due to excessive water intake.

Sodium isn’t the only mineral that gets diluted when we drink too much water. Potassium, magnesium, calcium, manganese, selenium, and other trace minerals can also be diluted in the bloodstream. go back up

Potassium

Potassium is necessary for all cellular communications and nerve conduction. It is present in a variety of foods, including almonds, bananas, cucumbers, apricots, avocados, tomatoes, potatoes (especially the skins), wheat germ, and others. Low potassium in the bloodstream is called hypokalemia.

Mild hypokalemia often has no symptoms, although it can cause a small elevation in blood pressure and can sometimes lead to an irregular heartbeat. Moderate hypokalemia can cause muscle weakness, muscle pain, muscle cramps (due to impaired skeletal muscle function), and constipation (due to impaired smooth muscle function). go back up

Calcium

Calcium is necessary for healthy bones, normal muscle contraction, and nerve conduction. Dietary sources of calcium include dairy products, broccoli, cauliflower, pinto beans, aduki beans, soybeans, almonds, Brazil nuts, hazelnuts, sunflower seeds, sesame seeds, molasses, and others.

Mild calcium deficiency (such as might occur during exercise rather than long-term dietary deficiency) can cause muscle cramps, palpitations, numbness or tingling in the hands and feet, irritability, and mental confusion.

A recent study showed that competitive cyclists are much more likely than average to develop osteoporosis because intense physical exercise for long periods of time can deplete calcium in the body. (4.5)

Magnesium, vitamin C, and vitamin D are necessary to aid calcium absorption. go back up

Magnesium

Magnesium is involved in several hundred enzymatic reactions in the human body, many of which contribute to energy production (conversion of glucose to ATP) and cardiovascular function. It is the “anti-stress” mineral, as it works to relax skeletal muscles, as well as the smooth muscles of the blood vessels and digestive tract. It is essential for modulating the electrical potential of cell membranes, allowing nutrients to flow in and out of cells.

Symptoms of magnesium deficiency can include fatigue, poor appetite, irritability, insomnia, muscle tremors, and muscle spasms. Severe magnesium deficiency can lead to muscle cramps, mental confusion, and coronary artery spasm.

Dietary sources of magnesium include dark green vegetables, almonds, walnuts, cashews, Brazil nuts, wheat bran, wheat germ, millet, brown rice, avocado, dried apricot, and soy products. go back up

How do we get enough electrolytes while staying hydrated?

For mild to moderate exercise (say 60 to 90 minutes of moderate-intensity activity), eating a few salted almonds, dried apricots, avocado, bananas, or pickled gherkins after your workout is probably enough. 1/8 teaspoon of sea salt in one of your water bottles or sports drink bottle wouldn’t hurt, but you’re probably fine without it. Regular iodized salt contains only sodium chloride and lacks the other trace minerals found in sea salt, so sea salt is what you need for this application!

For more extreme exercise (say mountain biking for 4 hours in 100 degree heat), you’ll need an electrolyte replacement sports drink for at least 50% of your fluid intake. You may need additional potassium, calcium, magnesium, and vitamin C supplements. Camelbak’s Elixir contains all of these minerals in an easy-to-carry tablet form that dissolves quickly without leaving a powdery residue in your water bottle. (No, I am NOT a representative of Camelbak, nor do I sell their products. I am just happy with my experience with the Elixir!) Many companies are now making jelly beans, gelatin blocks, and other electrolyte replacement chews. My favorites (based on my taste preference AND a high percentage of organic ingredients with minimal artificial stuff) include Sharkies and Cliff Blocks electrolyte chews.

If you routinely do extreme exercise (more than one day a week), you should also take a basic multimineral supplement that provides the macrominerals discussed in this article along with plenty of trace minerals. I would be happy to make recommendations, and i have a multimineral supplement in my office. go back up

First aid for electrolyte depletion during exercise

If you experience excessive fatigue, malaise, dizziness, disorientation, nausea, vomiting, palpitations, muscle pain, or muscle cramps during a hot weather workout, STOP what you are doing!

Go inside and refresh yourself, have a glass of fresh apple juice with ¼ teaspoon of salt and a banana or pickle if your stomach allows it.

If you do not feel better within 30 minutes, seek medical attention; you may be in a state of electrolyte depletion requiring intravenous replacement to prevent a medical emergency.

Take care and have fun with your summer activities!

1. Almond CS, Shin AY, Fortescue EB, et al. (April 2005). “Hyponatremia Among Runners in the Boston Marathon”. N.English J.Med. 352(15):1550-6.

2. “Statement of the Second International Consensus Development Conference on Exercise-Associated Hyponatremia 2007”

3. Siegel AJ, Verbalis JG, Clement S, et al. (May 2007). “Hyponatremia in marathon runners due to inappropriate secretion of arginine vasopressin”. Am. J. Med. 120 (5): 461.e11-7.

4. Smathers AM, Bemben MG, Bemben DA. Comparisons of bone density in male competitive road cyclists and untrained controls. Sports exercise Med Sci. 2009 February; 41(2):290-6.

5. Barry DW, Kohrt WM. BMD decreases over the course of a year in competitive male cyclists. J Hueso Minero Res. 2008 April; 23(4): 484-91.