GLOSSARY

Sodium Channel is preferentially permeable to sodium; voltage-gated types initiate and propagate many electrical signals.

An ion channel is a protein allowing selective ion movement along its driving force, with gating by voltage, chemical signals or stretch. It differs from an active pump and does not directly use ATP for each transported ion. Opening can rapidly change voltage; the outcome depends on ion, distribution and tissue, not simply the presence of sodium, potassium, calcium or chloride on a food label.

Sodium supports extracellular fluid volume, nerve signaling and intestinal uptake of some substances. Dietary sodium arrives in salts and additives, not as free metal. Its role in muscle function does not mean salt is needed before every workout. Usual food intake, actual losses and environmental conditions determine whether the plan needs adjustment, rather than the nutrient's physiological importance alone.

Ions move under both concentration and electrical forces; the electrochemical gradient combines these components. Membrane potential describes voltage across a membrane, not the muscle's food energy. Selective permeability and ion distribution both matter. This helps explain muscle excitation, but the existence of a gradient does not establish that an electrolyte supplement accelerates nerve signaling in an athlete already adequately supplied.

Sodium is mainly the extracellular cation and potassium mainly intracellular; chloride and other anions contribute to charge balance. Selective membranes, transporters and energy expenditure maintain these distributions. Blood concentration does not directly report muscle content. Movement between compartments may occur faster than changes in total stores and can affect a sample even without a corresponding dietary change.

The sodium-potassium pump uses ATP to move sodium outward and potassium inward, maintaining gradients. Calcium pumps remove calcium from the cytosol into external or internal stores, helping end signals and support relaxation. These are regulated proteins: eating more ions does not replace energy supply or membrane health, nor does it drive pump activity upward without physiological limits in an already adequately supplied athlete.

Contraction couples membrane excitation to intracellular calcium release and reuptake and requires ATP. Several electrolytes function together, but this does not imply equal dietary amounts or immediate supplements for all of them. Exercise cramps are multifactorial: fatigue, individual history and session conditions matter alongside fluid and salt. A single-mineral explanation does not adequately describe every episode or establish its treatment.