Training the different kinds of Muscle Fibers

We know that exercises can train whole muscle groups involving more than two joints or isolated muscles, involving one joint. The workout can be structured around reps, circuit or interval training according to the results one needs to acquire. However, all training sessions should be geared to train 3main aspects, namely: Resistance, Hypertrophy (tissue cell enlargement) and Explosive Force.

These are the main aspects that must be taken into account:


Exercises with medium/low reps and weights that correspond to a low percentage of force with respect to your maximum active force limit. The reps should be slow to stimulate the Slow Twitch muscle fiber.


Works on medium to high weights with fast and explosive repetitions. This also trains the speed resistance.

Maximum Active Force

It gets trained with one or more weights that correspond almost perfectly to the maximium strength your muscle is able to hold. The Fast Twitch muscle fibers will be stimulated.

Isometric Strength

Gets trained through the contraction of the muscle and weights or handles that do not move. It is a static movement that produces a strong arterial pressure.
The muscle can use different types of contraction: isometric, where no movement takes place and isotonic, where movement takes place. The isotonic contractions can be divided into two types which are: concentric contractions ie. the muscle shortens when it picks up a load and eccentric contraction ie. the muscle lengthens as it resists a load.

As we said previously, the muscles have differing kinds of fibers:

  • Slow Twitch: Muscle fibers that are slow to contract but that are not easily fatigued. Their metabolism is mainly aerobic.
  • Fast Twitch type A: Muscle fibers of intermediate strength and velocity that have an intermediate fatigue point. Their metabolism is anaerobic (production of lactic acid)
  • Fast Twitch type B: Muscle fibers that are fast and powerful, with very rapid contraction times. They fatigue fast. Their metabolism is anaerobic (lactic acid based and non lactic acid based)

The following table allows you to know how much weight you should be using per number of repetitions

AF% = percentage of active force
RM = maximum repetitions
100% – 1
95% – 2
90% – 4
85% – 6
80% – 8
75% – 10
70% – 12
65% – 15
60% – 20

For training purposes you can use dumbbells, barbells, cables or machines

Health benefits can you expect to have from an appropriate weight training program:

  • Muscular hypertrophy (enlargement)
  • Hormonal stimulation (better hormonal balance and sense of well-being)
  • Capillarization (more blood and oxygen to body)
  • Concentric Hypertrophy of the heart (reduced risk of heart disease)
  • Better coordination and proprioceptive capacity (better sense of your body in movement)
  • Increase in joint cartilage and osseous tissue (only with certain types of training)
  • Increased joint mobility (via the stretching routing that is strongly advised at the end of each session)
  • Bettered cardiovascular system (by training with high reps and medium/low weights)
  • Increase in strength (muscles and tendons)
  • Strengthening of the respiratory system

One Response to Training the different kinds of Muscle Fibers

  • Everything is very open with a really clear description of the challenges.
    It was definitely informative. Your site is useful.

    Thank you for sharing!

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