Fast and Slow Twitch Fibers

All has happened in sports discipline, as much as we trained, it can be to find someone who, with less effort, we exceed in certain actions, such as racing background, speed… unless we find apparent reason.
Calm down, this has a scientific explanation and takes place by our physical Constitution. We all have some characteristics of biological order that we genetically predispose to have greater or lesser performance in according to that according to these activities are more focused in the resistance or the immediate work of strength and power.

In order to determine that that activity will have greater chance of becoming a great talent, we must study the differences between the different types of muscle fibers. There are two types of fibres:

  • Slow twitch fibers, red or oxidative: these fibers are long and pale, this color is due to the slow twitch fibers have a high content of Myoglobin (hemoglobin), these fibers tend to be more abundant in the muscles responsible for low voltage activities but great continuity Fund, in contrast, we have
  • Fast-twitch fibers, white or glucolitcas: predominate in the muscle that is used when you need to develop great forces, fibers are as their name implies fast, powerful contractions and quick fatigue, predominate in the athletes who compete in activities of strength speed and short duration

While it is true that both fibers are used in all sporting disciplines, an athlete’s Fund can reach a percentage of slow twitch fibers of up to a 82% faced with the 70% of white fibers that can count the sprinters.

According to research studies come to the conclusion that the fast-twitch fibers, they experience one fatigue more than slow-twitch fibers.

Here is a summary of the differences between both fibers clear:


  • A low aerobic capacity
  • A high capacity glucolítica (lactic acid)
  • A low capillary density
  • A large force of contraction
  • A high fatigue
  • A large distribution in athletes who are not engaged in endurance tests

Slow twitch:

  • A high aerobic capacity
  • A low capacity glucolítica (lactic acid)
  • A high density hair
  • A small force of contraction
  • A low fatigue
  • A large distribution in athletes who are engaged in resistance activities

In future post on HowStuffWorks, we will indicate what kind of exercises are more correct to work according to which fibers and we will help you to increase your fibrillar resources.