Electrolytes (sodium, potassium, magnesium, calcium, chloride, phosphorus, bicarbonate) are minerals that carry electrical charge in solution and are essential for nerve conduction, muscle contraction, fluid balance, and pH regulation. Our research confirms the primary supplemental use is exercise rehydration — exercise-associated hyponatremia (EAH) kills more marathon runners than dehydration. The key finding that reshaped sports nutrition: plain water during prolonged exercise DILUTES blood sodium, causing potentially fatal brain swelling. Modern rehydration science emphasizes sodium replacement (500-1,000mg/L) over just fluid volume. The WHO-ORS (oral rehydration solution) is the single most life-saving medical intervention in human history (>50 million lives saved).
Electrolytes maintain the electrochemical gradient across cell membranes (Na+/K+ ATPase pump), which is fundamental to: (1) nerve signal transmission (action potentials); (2) muscle contraction (calcium flux triggers actin-myosin cross-bridging); (3) fluid balance (sodium draws water via osmosis — the Starling forces); (4) pH regulation (bicarbonate buffer system). During exercise, sweat losses of 0.5-2.5L/hour deplete sodium (primary sweat electrolyte) and smaller amounts of potassium, magnesium, and calcium. Replacing water WITHOUT electrolytes dilutes blood sodium (hyponatremia) — at <125 mmol/L, brain swelling (cerebral edema) can be fatal within hours.
Reviewed by the Scan Dose Research Team and Clinical Advisory Board | Last updated:
Not medical advice. Based on published clinical research and systematic reviews.