How many reps and sets you should do is a hot topic. Experts and gurus have trouble to agree on what numbers gives you best return on investment. Of course, it also depends on what you are trying to achieve, do you want to build muscle mass or improve endurance.
First, let’s define what reps and sets are. A rep is short for repetition and is one complete motion of an exercise. A set is made up of a consecutive number of reps. For example, if you did two sets of 15 reps, you lifted the dumbbells 15 times, rested for a while and then lifted the dumbbells another 15 times.
One very important thing is that the last rep must really be the last you can do with good form. Lifting a light weight 12 times is just waste of time if you can do another 10 or 20 reps. The weight has to be heavy enough so that you can’t do any more reps.
If you want to build muscle mass, you get best result by using heavy weights. One or two sets of six reps is a good target. But note that this is not a strategy suitable for beginners. If you are just starting out, you should start slow and increase the intensity later on. According to many experts, just one set of 4-6 reps is the best way of building muscle mass. Others disagree, a second set is necessary for most people in order to get the most out of the exercise. It very much comes down to if you can keep the intensity high enough or not.
If your primary objective is to build muscle mass, a third set is mostly a waste of time and any additional sets after that may even be counterproductive. If you work out too much, your muscles have to focus on repairing themselves rather than growing. So, yes you need to push yourself but don’t overdo it.
If you want to tone your muscles or improve muscular endurance, you should do more reps in every set. You can also increase the number of sets. Three sets of 10 or 12 reps is often recommended. Although you can find people who recommend very high numbers of reps, the main view is that you don’t gain much at all if you do more than 15 reps.
If you manage to do the sets with high intensity, as you should, there is not much to be gained by doing more than three sets. Also don’t let momentum and gravity do part of the work, quality is much more important than quantity.
For best result, you must give your muscles time to recover and grow. Muscles don’t grow during exercise, they grow afterwards. If you want to build muscle mass, you should give your muscles at least three or four days to recover. It is best to train a muscle group just once a week, this gives the muscles enough time to recover and grow. Even if your aim is not to maximize muscle grow, it is best to only train a muscle group one or twice week.