40, hold the stretch for a little longer, 60 seconds at least. stretching properly protects you from injuries related to working out.
when you want to add muscle mass to your frame, make sure you are getting enough protein. protein is a chief building block of muscle, and consuming not enough of it may cause you to have less muscles, which kills the reason of trying to bulk up. you might need about 1 gram of protein for every pound in your body each day.
it can be beneficial to train opposite muscles during the same workout. examples are the muscles in your back and the muscles in your stomach, or the 