Know Your Muscle Fibers
Right Knowledge is very important while you are doing your workout or following any diet regime. Muscle fiber influence your training in many ways and you should be aware about what are the roles of muscle fibers while doing any physical activity.
SLOW-TWITCH (Type I)
They are those kind of muscle fibers who can work for long hours without getting tired. For example a person running in a marathon needs more of slow twitch because it is more oxidative so it allow runner to run for a longer period of time. This is because these fibers have small cross- section area, many mitochondria (power house of cells) and they are resistant to any kind of fatigue i.e they have high aerobic capacity. These fibers are darker in color. They contract more slowly as compared to fast twitch fibers. Their force generation capacity is low as compared to fast twitch. Normally these fibers are 50 percent distributed in the entire body.
FAST-TWITCH (Type II)
They are those kind of muscle fibers who can generate large amount of power for a very short duration. For example a power lifter needs more of fast twitch as it is more glycolytic so the lifter can generate power but only for short duration because these type of muscle fiber gets fatigue easily.
They are divided into two types Type II a and Type II b.
Type II a are fast oxidative and have more mitochondria than Type II b but have some aerobic capacity but not as same endurance as slow twitch muscle, where as Type II b are fast glycolytic.
Differences are summarized in the table below –
Note: Distribution of slow twitch and fast twitch in your body varies by
- Varies in Different muscle group example: percentage of slow and fast twitch muscles is different in the deltoids and in hamstrings.
- Varies from individual to individual i.e. some people have more of fast twitch fibers than others. It influences one’s ability to perform speed and power events. For example weight lifters have 60-90 % fast twitch fibers in muscle they use to perform.
- Varies by genetics, if they are genetically determined they cannot be changed but training can change the oxidative and glycolytic capacity.