Unfortunately, if your body is structured such that you are predisposed to these types of injuries, the only suggestion that I can make is to train natural and allow your body enough time to recuperate between training sessions.
It is seldom that you hear of natural guys tearing a pec...it is always the juicehead who has a massive pectoralis and a tiny pec tendon or perhaps a juicehead with a massive scar-tissue-laden pectoralis that gets hurt. Elasticity in the contractile and connective tissues is critical and unfortunately, using
anabolic steroids reduces the elasticity of both.
Simply put, increasing connective tissue strength and size takes time. your tendons simply need time to catch up to the contractile force of the pectoralis. I use to think that
growth hormone would solve the problem but it doesnt. The body simply needs time.