I have been playing soccer with my friends two times a week for the past two years but now I fell that I need some other physical activity too, something a bit more serious. I have heard good things about progressive resistance training and I need to know if that is a medically approved way of muscle exercising? I ask this because I have some slight heart issues which I control with medications.
Hmm, in that case you need a serious consultation with a doctor. Even if it is medically approved, it still might be too much for your heart condition. Still, if you have managed to play soccer without any complications, then perhaps you can engage yourself in some other types of exercises. But, engage only in physical activity approved by your doctor.