How many repetitions are ideal for building muscle?

How many repetitions do you need to do for building muscle?

This question keeps coming up. Some say you need 8 - 12 repetitions for building muscle. Others talk about 5 - 10 repetitions of the same exercise without a break to achieve maximum muscle growth. Let's get to the bottom of it.

What is a repetition?

A repetition means performing one movement of an exercise. The training weight is therefore moved once through the complete range of motion. A repetition thus consists of a concentric part (the muscle gets shorter), an isometric part (the muscle stays the same length) and an eccentric part (the muscle gets longer). So it makes a huge difference whether you perform the exercise 12 times at a fast tempo or 12 times as slowly as possible. More on that later.

Your goal is what matters

Your training goal is decisive for answering this question. The adaptation to training is not the same whether you perform 1 repetition with maximum weight or do 12 repetitions. If you move your maximum weight once, the firing rate is increased. Your brain sends more impulses per unit of time to your spinal cord. That means you will be able to apply more "strength" for exactly this movement. A transfer to other movements is, however, rather unlikely. If you do, for example, 10 repetitions very slowly until complete muscle exhaustion, your rate of muscle building is increased and your muscle begins to produce muscle proteins.

Can your muscle count the repetitions for building muscle?

You hear about repetition numbers again and again. However, your muscle cannot register the number of repetitions. What is decisive for the training adaptation is therefore the duration of tension rather than the number of repetitions. The number of repetitions can serve as an aid to estimate the duration of tension without needing a stopwatch. Let's assume you perform 6 repetitions with the movement rhythm 3-2-3-2, then you will reach a tension duration of approx. 60 seconds. A tension duration of approx. 60 seconds to 100 seconds has proven to be particularly effective for muscle building training. A shorter tension duration leads to less strong adaptations regarding muscle building. Rather, the neural adaptations are promoted (including the increase of the firing rate).

So how many repetitions for building muscle should I do now?

Basically, you could train with a stopwatch and choose a weight that you can move, or hold at the point of greatest tension, for at least 60 seconds and at most 100 seconds. Yes, you read that right. You could even trigger the muscle-building stimulus without any problem with just one repetition!

This is actually one of the most effective variants for triggering the muscle-building process. You have probably already noticed that the training resistance fluctuates during the movement. This is because you cannot produce the same torque at all joint angles. In addition, the resistance can become greater or smaller due to the lever. Your muscles also do not have the same strength depending on muscle length. If you now hold the resistance at the point of greatest muscular tension, the resistance no longer changes during the entire tension duration. Furthermore, your muscle is no longer supplied with fresh blood and thus no longer with new oxygen. According to studies, this leads to a significantly higher rate of muscle building.

If you train by repetitions, do it right!

If repetitions for building muscle are specified, then the time per repetition must also be defined. If you perform 8 repetitions with a duration of 4 seconds per repetition, you have a total tension duration of approx. 32 seconds. If you perform these 8 repetitions at 10 seconds per repetition, you already reach 80 seconds of tension duration. As mentioned above, the tension duration should be approx. 60 to 100 seconds.

So if you perform 8 repetitions of 10 seconds each until complete muscle exhaustion, you have already set the muscle-building stimulus optimally with 80 seconds. However, if you do 8 repetitions of 4 seconds each, you are only at 32 seconds. In this case, you should do several sets of this exercise, because with 30 seconds of tension duration, hardly any muscle-building results are to be expected.

Another thing to consider is the duration per repetition. If you perform the exercise too quickly (any repetition under 8 seconds is too fast!), the resistance moves on its own to a certain degree. That means the resistance will not act fully on your muscle during the whole repetition. This logically again affects your effective tension duration! So make sure you perform the repetitions slowly!

So it is not decisive how many repetitions are done for building muscle, but the effective tension duration of the exercise!

Let's go, go for it!

Besides tension duration, protein intake is also decisive for building muscle. You can find high-quality protein products here.