It is now a definite fact that the most effective type of workouts are those that are short intense ones. It is in general agreed in the sport that the best most conclusive workouts to support muscle growth are the ones that last between 45 minutes to one and a half hours. The number one mistake of many bodybuilders is that they reduce their workout times to the limits recomended but dont train any harder. Now the reason for having short workouts is that you are training so intense that your body wouldnt be able to handle anymore than the times stated above. This means working as hard as you can, going all out, going to levels you never previously thought possible. It means reaching muscle failure on every set. The human body is very complex, very clever and will do all in its powers not to do new things or things that it hasnt done before. IN SHORT it will try and resist the changes you are trying to cause it. This is where being intense comes into the equationo, you are pushing through boundries and limits it has not gone to before and will be forced to grow. Hammering your muscles is sure going to cause plenty of damage so make sure you get your rest. Remember all you have to do is follow the other Bodybuilding Commandments and you are on your way to success