Q. I want to know about yoga effects in the body? How is it useful from other body training means of exercise?
A. The ashtanga yoga system is designed in such a way that at the end, an aspirant can see and worship the Paramatma in the heart. The aim is thus God realization and not to have a healthy and strong body so that we can have better sense gratification. If done properly we do get the benefits of a good and healthy body and mind, good concentration and proper sense control which help in the final aim of God realization.
Regarding other forms of exercise, Srila Prabhupada recommended brisk walking.