Magnesium (Mg) is a one of abundant minerals in human body. Mg play role as a co-factor to activate some enzymes, especially gluco-regulated kinases. It is well known that activities of these enzymes are affected by exercise exertion. However, Mg balance was not elucidated enough even if in sedentary condition. In this study, we evaluate the Mg requirement in rats with different type of exercise measuring apparent absorption and urinary excretion, concentrations in serum and skeletal muscle, and the expression of TRPM7, which has been identified as a Mg-permeable ion channel that primarily is required for cellular Mg homeostasis in their skeletal muscle.