Bodybuilding repetitions – how many to do?

For many the most boring thing in the gym is having to count the repetitions, have you ever wondered why? Why do we have to do 15 reps or 8?

If you answered that you have to do 15 for resistance and 8 for hypertrophy, it is almost right, but it is not that simple.

In many gyms the training comes ready, as a recipe, everyone does the same training and seeks to follow this line of reasoning: 15 to dry and gain resistance and 8 to gain hypertrophy and strength.

What is the repetition in bodybuilding for?

The repetition of the exercise serves as an intensity level and this is visible when we start an exercise to do 15 repetitions, the load is very light at the beginning, to feel difficulty in the 12th, 13th repetition … That is, the intensity is low.

The Maximum Repetition (RM) is the maximum number of repetitions you can do with a load. Now understand that 1RM (1 repetition maximum), will be the maximum of your strength (100%), you must have already done in the gym or at home, some exercise that was unable to perform more than 1 repetition. Remember?

So we have:

 (% of maximum force) Number of repetitions
100% 1
99% to 90% 2 to 3
89% to 80% 4 to 6
79% to 70% 7-10
69% to 60% 11 to 15
59% to 50% 16 to 20
49% to 40% 21 to 30
39% to 30% 31 and more

In previous articles, I explain that for resistance training we use 50% – 70% intensity which takes us in 20 -15 repetitions, and in another article I show that for muscle hypertrophy the intensity has to be between 70% – 90%.

With that, it was already possible to understand a part, the reason for repetitions and why they always use that “cake recipe”.

Other muscle variables

In the muscles we also have different types of fibers and each fiber will respond to a different energetic substrate.

This means that when we do strength training, we prioritize type II fibers, which use ATP-CP (the fastest way for energy production and muscle contraction), but our ATP-CP reserves last for about 10 seconds, time to do 3 repetitions.

In a hypertrophy workout we use muscle glycogen, the glycogen stores can last about 15 to 60 seconds, enough time to do 7 to 12 repetitions.

Muscle endurance workouts use type I fibers, which use oxygen as energy and can last for many hours.

It is clear that if you do 7 instead of 8 it will be practically the same thing, as well as 16 instead of 15, the intensity is almost the same, the numbers that teachers use is just a pattern, to identify the intensity. Don’t get stuck in it.

Another important factor is biological individuality, because each body responds differently, after all, each person has different amounts of fiber types I or II. Each has its endurance, conditioning and strength. Although most serve that table above, 3 × 15 for you can still give hypertrophy.

I conclude this article, showing that repetitions are indeed important in your training, but that it is necessary to do a periodization for your training, so that you are always evolving.


Leave a Comment