How to build core (body) strength?

Is it okay to strength train or body build for an hour or more?

• I read a few times on some sites where it said no strength training for more than 40 minutes or else your body releases a certain hormone which could break down the muscle. I'm doing some strength training which is moderately intense with exercise bands. Mostly with the upper body. I've been working out for a half hour but I find that my muscles have become stronger and that duration doesn't really do anything. I want to increase my training by adding a second set of reps. This will increase my work out time to an hour. Is that okay to train for an hour for muscle training? Will my muscles start eating away? I'm planning to start my reps in another hour or so. Thanks very much.

• Answer:

  the hormone your thinking of is cortisol and if you train for an hour you will not lose muscle... BUT keep in mind that if your are a noob to lifting there is no need to train for an hour. if you feel like your up for it then do it, u know yourself more than me. Its crucial that you have good postworkout nutrition ( Protien shake with a lot of carbs). I recommend doing regular weight lifting instead of exercise bands. dont ask questions here everyone is an artard... go to bodybuilding.com ; T-Nation.com or leanbulk.com