Fast- and Slow-Twitch Muscles

The human body has different types of muscle fibers that aren’t well explored by people who aren’t focused towards anatomy. The classification of these muscle fibers is done on the basis of how they tend to produce energy. To be precise, you can train muscle fibers differently with specific exercises that support the generation of energy. It should be known that, generally muscle fibers are classified as slow-twitch or fast-twitch.

The below mentioned article would carefully examine the importance and functionality of slow twitch and fast twitch fiber.

Vital Pointers of Slow-Twitch Muscle Fibers

  • These fibers comprise of mitochondria, the responsible organelles which utilize oxygen for the creation of adenosine triphosphate (ATP) (chemical that supports muscle contractions).
  • They are also termed as red fibers since they comprise of blood-carrying myoglobin, responsible for creating a darker appearance.
  • Since they can deliver their own energy source, slow-twitch fibers are capable of sustaining force through an extended time period; however, they cannot generate any significant force.
  • With slow-twitch fibers, there is a low activation threshold, that is, they are the first to get recruited at the time of muscle contraction. Suppose they aren’t able to generate the necessary amount of force for a certain activity, then fast-twitch muscle fibers are aligned for action.
  • Practicing steady-state endurance training, mitochondrial density gets increased. Therefore, it improves the efficiency of how our body uses oxygen for the production of ATP.
  • It should be known that tonic muscles accountable for maintaining posture hold a higher concentration of slow-twitch fibers.

Methods to Train Slow Twitch Fibers

Here are some smart and precise ways to train slow twitch muscle fibers for better strength.

  • Practice exercises focused at resistance-training using lighter weights and slower movement rhythms for achieving greater number of repetitions. Such actions would help you involve the slow-twitch fibers into aerobic metabolism.
  • Include body-weight exercises to achieve higher repetitions. This proves as an effective style to check aerobic metabolism, thereby, improving the aptitude of slow-twitch fibers.
  • Try circuit training that includes alternating exercises with lesser to no rest while holding lighter weights.

Vital Pointers of Fast-Twitch Muscle Fibers

  • These muscle fibers hold a high threshold and get recruited at the time when force demands are higher which cannot be fulfilled slow-twitch fibers.
  • Fast-twitch fibers are classified as fast-twitch IIa – fast oxidative glycolytic, since they utilize oxygen to convert glycogen to ATP, and the other one being fast-twitch type IIb – fast glycolytic that depends on ATP deposited in the muscle cell for generating energy.
  • It is vital to know that fast-twitch fibers are known to develop more force; however, are quicker to exhaust as compared to slow-twitch muscle fibers.
  • The phasic muscles responsible for offering body movement contains a larger density of fast-twitch fibers.

Methods to Train Fast Twitch Fibers

  • Select resistance training using heavy weight for exciting muscle motor units, thereby, activating supplementary muscle fibers. Do remember, heavier the weight, the extra would be the count of fast-twitch fibers getting recruited.
  • Select power-based movements, be it a kettlebell, barbell, medicine ball etc. This will help to recruit higher levels of fast-twitch muscle fibers.
  • Since fast-twitch fibers tend to fatigue quickly, therefore, focus the use of explosive movements for a limited count of repetitions in order to gain maximum effectiveness.


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