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What A Bodybuilder Should Know About Fast/Slow Twitch Fibers




         You may think that you don’t need to complicate yourself with such kind information. But you are wrong. The more you know about how your body function and build muscle, the easier for you to create the best condition for this. Take some time and read this article. We wrote it in a very easy and simple manner so it will take only a few minutes to get a clear image of slow/fast twitch fibers.

         All bodybuilders and not only should know that body is composed of two different types of muscle fibers: slow twitch (type I) muscle fiber and fast twitch (type II) muscle fiber. The last one type of fiber can be further divided into intermediate fast-twitch fibers (use both aerobic and anaerobic metabolism to create energy) and fast twitch fibers that use only anaerobic metabolism to create energy.

         The percentage of types of muscle fibers varies from one person to another. Thus two bodybuilders may have the absolutely different percentage of slow or fast twitch fibers. It is believed that for the average person the ratio of fiber types is about fifty-fifty.

         They can not only differ from one person to another but even from one group of muscles to another group. For example, the largest number of slow fibers is situated in legs.

What is The Role of Slow Twitch Fibers  And Why We Need Them?

What is The Role of Slow Twitch Fibers  And Why We Need Them?

          During our lives, we execute movements that vary by the speed of execution and energy consumption. As we said each type of twitch fibers use different types of source of food to create energy, accordingly different types of energy. Fast twitch fibers (white fibers) are involved in work when fast movements are executed. The reason for using such type fibers at large scale is low energy costs.

         Slow muscle fibers (red fibers) work during lifting light loads. These are mostly aerobic exercises, such as jogging, running. Slow twitch fibers can be also used during movements with weights, but you have to perform them very slowly.

            Initially, it was believed that fast twitch muscle fibers are causing muscle growth. After analyzing the muscles of bodybuilders, it was proved that slow twitch fibers can reach the same size as the fast fibers. So, the conclusion was that slow fibers have to be trained too. The training in bodybuilding has other goals than in case of other types of sports.

Let’s see the main purpose of bodybuilding and the reasons that distinguish it from other types of sport:

  • In bodybuilding, the functionality is nothing compare to the appearance of an athlete. This doesn’t mean that it is completely absent;
  • The main goal in bodybuilding is to increase muscle mass;
  • Bodybuilders train all muscles for achieving muscle growth.

fast slow fibers

         In order to get the most out of your workout, you have to know what triggers the growth of muscles. Some of these factors are stress, hormones, amino acids and the list isn’t by far completed.

How To Build Fast And Slow Twitch Muscles Fibers?

How To Build Fast And Slow Twitch Muscles Fibers?

          The first one is training for building fast fibers, always followed by training of slow fibers. Slow fibers recover during 2-3 days. If you train different types of fibers on individual training you have to take a break of 2-3 days. Deadlifts are the good example to train both of them simultaneously. They cause fast twitch fibers to work, and because you perform them slowly slow fibers get in work too.

Must Read: How to Find the Best Deadlift Grip For You?

           You can choose to work slow and fast fibers apart, doing many reps with small weights and few reps with big weights. The best will be to train these types of fibers in different days since they work together but grow just one of them. As you see, we can talk about rapid repetition and slow repetition.

          In case of rapid are involved in work more muscles than in case of slow and concentrated movements. For example, when pumping the press, rapid repetition involve some abdominal muscles that are not involved in slow exercises on specific abdominal muscles.

          Switch to load repetition to develop strength of your muscles. The only condition is that weight should be greater than 50% of your weight limit. It is important that the number of fast reps was 25-30. Slow repetitions allow the muscles to work at full capacity.


           As a result of slow reps are utilized initially slow muscle fibers, and as the number of reps increased come into play fast muscle fibers. These exercises help increase muscle size, as they damage both fast and slow muscle fibers. If you chose to do exercises in a slow tempo then you keep your muscle under pressure for a long time.

            Also, have to be mentioned that after training of slow twitch muscle fibers is not recommended to do another type of exercise. Just go home, eat something rich in protein and rest. Don’t forget that muscle grow when you rest and not in the gym.

Must Read: 5 Must To Read Tips To Build Muscle Fast


Building muscle mass is what I like to talk about. If your aim is to build a solid body, then my posts would be very beneficial to you. I always want to know your opinion, so don't hesitate to drop a line below or contact me.

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