mEq/L

mEq/L stands for milliequivalents per liter. It is a unit used to measure the concentration of charged particles (ions) in a solution. A milliequivalent takes into account both the amount of substance and its electrical charge; for monovalent ions such as sodium, one milliequivalent equals one millimole, while for divalent ions like calcium, one milliequivalent equals half a millimole.

Understanding mEq/L in Sports Drinks

Measuring electrolytes by weight alone can mislead because ions carry electrical charges that influence how they behave in the body. mEq/L reflects the chemical reactivity of ions by factoring in charge; for example sodium and potassium each have a single positive charge, so 1 mmol equals 1 mEq, but calcium has two positive charges, so 1 mmol equals 2 mEq. Sports drink formulators use mEq/L to design beverages that replace sweat losses efficiently. Sweat typically contains about 20‑80 mmol of sodium per liter, which corresponds to the same number of mEq/L, so drinks providing 20‑30 mEq/L sodium are often recommended to support hydration. Using mEq/L also helps to compare different salts: 58.5 mg of sodium chloride (table salt) contains roughly 1 mmol or 1 mEq of sodium because sodium has one charge. In contrast, 74.5 mg of magnesium chloride provides 1 mmol of magnesium but counts as 2 mEq due to magnesium’s double charge. Keeping track of mEq/L ensures an appropriate balance of electrolytes and avoids excess or deficiency.

Practical examples

A home‑made sports drink might be prepared by mixing 30 g of glucose with ¼ teaspoon of salt (about 600 mg sodium chloride) in a liter of water. Sodium chloride dissociates into Na+ and Cl−; with sodium’s valence of +1, 600 mg (about 10.3 mmol) provides roughly 10.3 mEq of sodium. Commercial products often aim for around 20‑30 mEq/L sodium and 2–5 mEq/L potassium. If using potassium chloride, a salt substitute, you can calculate potassium content similarly because potassium also has a single positive charge. For divalent minerals like calcium or magnesium, remember that mEq/L doubles the mmol value. This knowledge allows athletes to adjust their beverages to match their sweat profile and training intensity.

In summary, mEq/L is a practical unit for expressing electrolyte concentrations because it accounts for both amount and charge. It allows comparison across different salts and helps athletes and formulators design beverages that match physiological needs. Understanding mEq/L facilitates more precise hydration strategies and helps prevent imbalances during prolonged exercise.

Related Terms: mmol/L, mg/L, Osmotic gradient, Carbohydrate concentration, Buffer