If you want to build muscle mass, you should not train too often. Muscles don’t grow during workout, they grow when you recover between the workouts. This means that it most people are actually doing more weight training than necessary.
But as pointed out this is true if you are trying to build muscle mass, which requires that you use heavy weights to push your muscles. After a heavy workout, your muscles need time to recover and to grow. You should at least give your muscles three or four days to recover. But you can of course train other muscle groups in between. In short, only train a muscle group once or twice a week. Pushing harder may be counterproductive.
When it comes to weight training, it is best to do short sessions. Quality is more important than quality. Make sure that you do the reps with perfect form. Not only does this maximize muscle growth but it also minimizes the risk of injury. It is also important to do the reps slowly, don’t let momentum and gravity do part of the work for you.
Low intensity weight lifting is easier on your muscles but that also means that you are not building much muscle mass. For endurance, lifting lighter weights is the way to go. But once again, you have to lift until your muscles can’t lift anymore. If you are using light weights and stop before fatigue sets in, you are not really getting much result at all.
Exactly how many reps and sets you should do is a hot subject. Experts and gurus have plenty of opinions about how to maximize your results. But two things are important to remember, and which most experts agree on; lighter weights means less risk of injury and that you must do a set until you are exhausted, the last rep should really be the last rep you can do.
Note that it is possible to train too much. It is not a good idea to lift weights for hours. You are only going to hurt your muscles, which will not help you at all. Your muscles will need to focus on repairing themselves, they will not have any chance of growing. Especially in the beginning it is important to not push yourself too much. Just do two or three sets per muscle group and limit yourself to a maximum of five or sex exercises per workout.
Remember that in order to grow your muscles need protein. Make sure that you eat enough during the week. If you want to build plenty of muscle mass, you may want to test whey protein supplement. It is the most efficient supplement when it comes to muscle growth, well worth the money.