Without electrolytes, physiological stability—called homeostasis—goes haywire and nerve and muscle function are disturbed, body fluid balance is upset, and other critical body workings are interrupted. These tiny particles of metals carry electrical charges and are present in all body fluids, including urine, blood and plasma. Without the proper timing and intensity of electrical impulses, nerve, heart and muscle function suffer, and might even stop in severe instances. If electrolytes are lost, as would happen in extreme exercise or sickness, replenishment is necessary, but in appropriate amounts. Imbalances can have terrible effects, and they can be caused by a deficiency or an excess. In the chemistry jargon, the prefix hypo- means “too little,” and the prefix hyper- means “too much.”
There is a laundry list of conditions that can lead to electrolyte imbalances, including dehydration and over-hydration, diabetic ketoacidosis, cancer, and head injuries like concussions. Kidney disease, though, is at the top of the list because the kidney’s job is to control fluid, electrolyte, and acid-base balance (Claure, 2012). The surest way to deal with electrolytes is through diet or supplementation, using an electrolyte replacement if necessary, as you might when exercising in the hot weather or when participating in endurance events.
We’ll start with sodium, since it’s the most abundant cation (positive ion) in the extracellular fluid (outside the cell). We need sodium to maintain normal blood pressure in addition to sending electrical messages to initiate a muscle contraction. Water will follow salt into the body. Too much salt will increase blood osmolality, meaning, in a way, that blood has more stuff floating in it because there is too little liquid. If that happens you get thirsty, and anti-diuretic hormone tells the kidneys not to let go of water. Opposite that, low osmolality means that the blood is more watery. If too much water is lost from sweat, respiration, urination, or the weather, or if too much salt is taken in, you have hypernatremia and may suffer symptoms such as disorientation, nausea without vomiting, rapid heartbeat, sunken eyes, or trembling. Your cells are drying out and the kidneys are conserving water, so you don’t urinate.
Losing sodium—hyponatremia—can happen when you drink volumes of plain water during a bout of intense exercise, especially in hot weather. Add lethargy and confusion to the hypernatremia symptoms. If sodium falls too low, permanent neurological damage can occur. People who have been forced to drink water to take a work-related urine drug test have fainted from hyponatremia, and have experienced hypertension and difficulty breathing.
Potassium is the primary cation inside the cell, where its major physiological role is the regulation of muscle and nerve excitability as the director of relaxation immediately following a muscular contraction initiated by sodium. Potassium imbalance is particularly monitored because of its relationship to coronary health and the heart’s ability to change electrical potential. Imbalance may cause arrhythmia. Excess (hyperkalemia) will cause cardiac arrest; deficit (hypokalemia) will irritate cardiac muscle and increase the chance of premature atrial or ventricular contractions, possibly leading to death. Potassium balance leaves little room for error (van der Meer, 1986) (Lindinger, 1995).
Magnesium, like potassium, is also found inside the cell, where it affects muscle function, energy production and carbohydrate and protein metabolism. Kidney disease is a major cause of hypermagnesemia, although taking too many magnesium-bearing antacids can contribute. Too much magnesium will cause lethargy, which is understandable because magnesium is a relaxant (Gold, 1990) (Spivey, 1990). Too little magnesium is common in the critically ill (Dacey, 2001), among whom mortality is high. Similar to hypokalemia, hypomagnesemia may induce cardiac arrhythmia, although milder signs occur before that happens. Muscle weakness, tremors, anorexia and dizziness are the more common. Can’t sleep? Got leg cramps? Magnesium may help (Young, 2002, 2009) (Geurrera, 2009) (Allen, 2012).
Although calcium is electrolytic, it seldom appears in electrolyte replacement drinks because most Americans, especially women, supplement at the behest of their doctors. Calcium works with phosphorus in an inverse relationship. When the value of one is high, the other is generally low. Calcium is involved in contraction of cardiac and smooth muscle, but also enhances the clotting mechanism, maintains cell membrane permeability and helps to transmit nerve impulses. You already know about the bones and teeth. Phosphorus also plays a role in bone formation, but is also needed for energy production and for macronutrient metabolism. By buffering hydrogen ions, it helps to maintain acid-base balance, as well. Like calcium, phosphorus needs are easily met without an electrolyte beverage. Deficiency is rare and occurs secondary to other conditions rather than as a result of low dietary intake. High doses of antacids may deplete phosphorus.
If your exercise regimen lasts more than an hour, especially in warm weather, you’re a candidate for electrolyte replacement. Hard games like tennis, cycling and marathon running, and assiduous resistance training call for such a beverage. During these times, you might need to drink a cup of electrolyte replacement every fifteen or twenty minutes to keep a steady pace and to avoid cramps. Thirst is not always the best barometer for gauging electrolyte needs. A beverage with sugar will compromise the bioavailability of minerals. Since sodium is the first electrolyte lost to heavy sweating, it’s a major consideration in repletion, so don’t be alarmed if you see high levels of sodium in your drink. If you’re interested in balancing electrolytes for yourself and the family, which is especially important when the kids get sick, take a look here: http://crampnomore.com/sportshealth/electrolytes-101.html. There’s an informative bulletin explaining the how and why of electrolytes, the balance of which is no laughing matter.
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