This mechanism is not just used by brain neurons — it is also used by nerves to tell muscles when to fire. Whenever I come home after running, I always have an electrolyte drink. Electrolytes are ions including sodium, potassium, and magnesium. After exercise, you can lose salt through perspiration. Salt (sodium chloride) includes the electrolytes sodium and chloride. It is therefore important to top-up your body's store of electrolytes to avoid muscle cramp, in which the ability to send correct firing signals to the muscles is lost.
