GLOSSARY

Magnesium Ion (Mg²⁺) is the electrically charged form acting as an ion in body fluids, distinct from the free element.

Magnesium is a cofactor for many enzymes, supporting ATP-related reactions, protein synthesis and neuromuscular function. Much is in bone and soft tissue, with only a small fraction in serum. Its essential metabolic role does not make a tablet an energy source. In an adequately supplied athlete, more does not guarantee greater strength, better sleep or elimination of every cramp.

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.

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.

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.

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.