In-Sync 4 is recommended to help support healthy muscle function, immune system, blood cell (oxygen) production and hair coat. Key ingredients include lysine and methionine for muscle development; thiamine, niacin, riboflavin, and vitamin B12 for red blood cell production; natural vitamin E and other antioxidants for immune system function; and magnesium, selenium, and DMG for muscle function. In addition, key ingredients such as magnesium, vitamin E, lysine, and DMG may also help manage muscle discomfort.