These days fitness pros, bodybuilding magazines, gyms and even certified personal trainers will tell you the optimal workout, whether for muscle mass or strength training, ranges from 30 minutes to an hour. They'll tell you that you can't lift heavy enough and go any longer than that, and that if you're not exhausted after an hour your weights are too light. They'll tell you that weightlifting for more than an hour produces too much cortisol that destroys your gains. supplementslove.com/primal-grow-pro