The manufacturer writes:

Potassium for blood pressure 
Potassium is an essential mineral and a key electrolyte for the body. Together with its function in the nervous system, potassium contributes to normal muscle function and to maintain normal blood pressure. Potassium is especially important to counteract sodium, which has been proven by the EFSA (European Food Safety Authority) to raise blood pressure.

Magnesium for the muscles
Magnesium is also an essential mineral. It contributes to:

    Reduction of tiredness and fatigue
    Normal electrolyte balance
    Normal energy metabolism
    Normal function of the nervous system
    Normal muscle function
    Normal protein synthesis
    Normal mental function
    Maintenance of normal bones and teeth

Note: The stated recommended daily dose must not be exceeded! Nutritional supplements are no replacement for a balanced and varied diet. Keep nutritional supplements out of the reach of young children.