Technical stuff about magnesium and Ca2+ https://pubmed.ncbi.nlm.nih.gov/6129804/
Ca²⁺ ATPase is a form of P-ATPase that transfers calcium after a muscle has contracted. The two kinds of calcium ATPase are: Plasma membrane Ca²⁺ ATPase Sarcoplasmic reticulum Ca²⁺ ATPase 1