There are two types of fibers in our muscles, type 1 fibers which are slow-twitch and type 2 fibers which are fast-twitch. the main distance between slow and fast fibers is, slow fibers help enabling long endurance activities lie running a long distance. On the other hand, fast twitch muscles get tired very easily and are used in powerful activities or movements.
Slow Twitch Fibers
Slow twitch fibers are used by the body when body requires long term exertion. They are type 1 fibers. These muscles are known to use efficient amount of oxygen to produce energy in the form of ATP. When our body has to perform functions which requires strenuous or long term activity, slow fibers come into play. That is the reason why slow twitch fibers are used more by athletes or for those who ride bicycles because their muscles need continuous supply of oxygen in order to generate ATPs. Slow fibers do not fatigue easily because of optimum supply of oxygen. Slow twitch fibers are also called red fibers due to the dark red color they have, this color is determined by the myoglobin in the muscle. They even use fat for energy.
Fast Twitch Fibers
Fast twitch fibers adopt the anaerobic metabolism to create energy for muscles. They are better when it comes to fulfill the rapid need of energy required by the muscle but they fatigue very easily and rapidly unlike slow twitch fibers. They even produce same amount of force as does slow muscle, but they are able to fire more rapidly. They are further divided into two types, Type IIa Fibers and Type IIb Fibers. Type IIa are intermediate fast twitch fibers. They are known to use both aerobic and anaerobic metabolism to produce energy. While type IIb use anaerobic metabolism only. Type IIb are the classic type of fast twitch muscles.
- Slow twitch fibers are used by our body for longer duration activity while fast fibers give a rapid burst of energy.
- There is a further classification of fast twitch fibers.
- Fast twitch fibers are known to fire more rapidly as compared to slow twitch fibers.
- Slow fibers do not fatigue easily because optimum amount of oxygen is supplied to the muscle but fast twitch fibers tend to fatigue easily.
- Slow fibers are also called red fibers because they are beefy red in color. Their dark red color denotes the quantity of myoglobin present in them.