Electrolytes: Understanding Replacement Options
BY SHAWN H. DOLAN, Ph.D, R.D., C.S.S.D.
Electrolytes are some of the most complex and misunderstood nutrients, which can make answering client questions about replacement options a challenge for many fitness professionals. For example, clients may ask why electrolytes are important, which specific electrolytes need to be replaced, as well as what options there are for replacing electrolytes before, during and after exercise. The following article explores this topic with the goal of helping fitness professionals feel better equipped to answer client questions and address concerns related to electrolytes.
Why are electrolytes important for physically active people?
Electrolytes are positively or negatively charged ions that conduct electrical activity. In the human body electrolytes must be present in proper concentrations to maintain fluid balance, muscle contraction and neural activity. The kidneys work to maintain electrolyte balance by conserving or excreting electrolytes. Water follows the movement of electrolytes, particularly sodium and chloride, meaning that water is drawn to locations where electrolytes are most concentrated. Therefore, electrolytes play a critical role in maintaining equilibrium of water throughout the body, particularly during exercise when electrolytes and water can be lost through sweating.
Do all electrolytes play an equally important role with regard to physical activity?
Electrolytes lost in high concentrations through sweat include sodium and chloride, while electrolytes lost in low concentrations include potassium, magnesium and calcium. Keep in mind that all electrolytes work together to maintain fluid balance in the body at rest and during physical activity, so be sure to educate your clients on all electrolytes, rather than focusing on only one or two. Table 1 lists common food sources, deficiency symptoms, and recommended intakes of electrolytes.
|Table 1. Deficiency Symptoms, Food Sources and Recommended Intakes of Various Electrolytes|
|Nutrient||Deficiency Symptoms||Food Sources||Recommended Intake*|
Loss of appetite
Tomato juice, sauce, soup
Table salt (1 tsp = 2300 mg sodium)
1300 mg for people over 50
1200 mg for people over 70
|Chloride||Changes in pH
Some fruits and vegetables (tomatoes, lettuce, olives)
2000 mg for people over 50
1800 mg for people over 70
|Potato with skin
|320 mg for women
420 mg for men
|Dairy (yogurt, milk, ricotta)
Collard greens, spinach, kale
1200 mg for people over 50
|*Recommended intake is based on Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride (1997) and Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate (2004). These reports may be accessed via www.nap.edu. Copyright 2004 by the National Academies of Sciences.|
One commonly held myth is that muscle cramping in active individuals is due to the loss of potassium; however, the amount of potassium in sweat is likely too low for this to be the culprit. Muscle cramping due to electrolyte imbalance is more likely associated with the loss of high amounts of sodium through sweat. Therefore, replacing sodium is important to maintain electrolyte balance for physically active individuals who experience high losses of sodium through sweating.