Difference Between Fast and Slow Twitch Muscles

Our human body has varied organ systems that have their respective different functions like – circulatory system, respiratory system, digestive system, skeletal system, tissue system, etc. The skeletal muscles include different muscles that join the bones with the tendons. Two skeletal muscles are meant to help in performing varied tasks are – fast-twitch muscles and slow-twitch muscles. Even these muscles comprise approximately 40% of the entire body mass.

Fast Twitch Muscles vs Slow Twitch Muscles

The main difference between Fast Twitch Muscles and Slow Twitch Muscles is that it lies in their name itself that is fast-twitch muscles are the ones that contract at a faster rate while comparatively, on the other hand, the slow-twitch muscles are the ones that contract at a very slow rate.

Fast Twitch Muscles and Slow Twitch Muscles

Fast-twitch muscles are defined as the muscles that are required the work with great effort but for less time. The other name used for these types of muscles is – Type II muscle. These are the muscles that get stressed very easily and are further bifurcated in other two types that is – Type II a and Type II b.

Slow-twitch muscles are defined as the muscles that are required in the work with less effort and for a large time. The second name used for these types of muscles is – Type I muscle. These muscles appeared bright red and contain a huge amount of myoglobin in them and comprise almost 80% of the entire human body.

Comparison Table Between Fast and Slow Twitch Muscles

Parameters of ComparisonFast Twitch MusclesSlow Twitch Muscles
DefinitionRequired for extensive work but for a short timeContracts at a slow pace and doesn’t get easily fatigued
Another NameType – II muscleType – I muscle
Speed of ActionFastSlow
Type of RespirationAnaerobic and aerobicAerobic
Blood supplyPoorGood
Consumption of OxygenFastSlow
Myoglobin AmountLessMore
Mitochondria AmountLessMore
Oxygen Consumption EfficiencyLessMore
DiameterLargeSmall
ColorPale (or white fibres)Deep Red (or red fibres)
Fuel UsedBurns the body fatBurns the body glucose
FatigueFastSlow
Best forSprinting, heavy weight lifters, etcCycling, marathon runner, etc

What is Fast Twitch Muscles?

Fast-twitch muscles are one of the types of skeletal muscles that are much needed for performing various activities of daily lives. As the name says, these muscles get contracted at a very fast rate when are in use. They are also known by a different name and that is – Type II muscles which are also bifurcated in other two types – Type II a and Type II b.

Type II a are the muscles that mainly perform the anaerobic activities but for up to 30 minutes or less than it and contain a certain good number of mitochondrial cells. While Type II b are the muscles that also perform the anaerobic activity but the time duration is limited to 1 minute or less than it. The energy generated is very high but for short time.

The blood supply in the muscle fibers is very poor because of which the appearance of the muscle fibers is very pale and they are referred to as white muscle fibers. After any activity, the individual gets easily fatigued and this helps in burning the high amount of fat in the body.

What is Slow Twitch Muscles?

Slow-twitch muscles are also among the types of skeletal muscles that help in performing various activities of the body for daily lives. These slow-twitch muscle fibers get contracted at a slow-paced rate. And another name used for the muscle fibers commonly is said to be – Type I muscle fibers.

These muscles are a great source of blood supply which makes them appear in deep red color which is why they are also referred to by the name red fibers. The amount of myoglobin and the number of mitochondrial cells in the muscle fiber is large.

On an average basis, these slow-twitch fibers cover 80% of the human body as they connect the bone with tendons. The muscles generate energy for longer times because of which the individual doesn’t feel fatigued for longer times.

Main Differences Between Fast and Slow Twitch Muscles

  1. Fast-twitch muscles are defined as the muscle that is mainly required to perform extensive activity for less time while comparatively, on the other hand, the slow-twitch muscles are defined as the muscle that is mainly contracted at a slow pace and doesn’t get easily fatigued. 
  2. Fast-twitch muscles are known by their second name as Type-II muscles while comparatively, on the other hand, the slow-twitch muscles are also known by their second name that is Type-I muscles.
  3. The speed of action for fast-twitch muscles is quick while comparatively, on the other hand, the speed of action for slow-twitch muscles is slow.
  4. Fast-twitch muscles perform both anaerobic and aerobic activities while comparatively, on the other hand, the slow-twitch muscle fibers perform only aerobic activities.
  5. Oxygen consumption of fast muscles is also fast while the oxygen consumption of slow fibers is very slow.
  6. The amount of myoglobin present in fast-twitch muscles is low while, on the other hand, the amount of myoglobin present in slow-twitch muscles is more.
  7. In fast-twitch muscles number of mitochondria is less while in slow-twitch muscles they are large in number.
  8. The efficiency of oxygen consumption in fast muscle fibers is slow while for slow-twitch muscles is fast.
  9. The diameter of the muscle fibers is large while comparatively, on another side, the diameter of type-I muscles is small.
  10. The fast-twitch fibers appear to be pale and are hence called white fibers while, slow-twitch fibers appear to be deep red and are, therefore, known as red fibers.
  11. Fast-twitch muscles use fat as their fuel while slow-twitch muscles use glucose as their energy resource.
  12. With continuous use of fast-twitch fibers the individual easily gets fatigued while, with the use of slow twitch fibers the individual doesn’t get easily fatigued.
  13. The fast-twitch muscle is mainly good for the person lifting heavy weights, a sprinter while, the slow-twitch muscle is good for a marathon runner or a cyclist, etc. 

Conclusion

To summarize the given topic this can be concluded that different muscles in the body have different functions to perform. The human body is a combined mixture of many processes that are known and unknown that helps the body to remain alive and active. And such are the skeletal system the bones, muscles, tendons, ligaments, joints, etc all are interconnected and they coordinate with the brain and nervous system to perform different actions.

Fast and slow twitch muscles are among them that help in performing a varied number of activities. These muscles can contract as mentioned by their name and also they consume oxygen at a different pace – fast-twitch fibers consume oxygen faster while slow-twitch fibers consume oxygen at slow speed. There are many such differences among them that have been mentioned above.

References

  1. https://journals.lww.com/investigativeradiology/Abstract/2001/12000/Effects_of_Aging_on_Muscle_T2_Relaxation_Time_.3.aspx
  2. https://journals.physiology.org/doi/abs/10.1152/ajpcell.1992.263.3.C598
  3. https://journals.physiology.org/doi/abs/10.1152/ajpregu.1997.272.3.r849
  4. https://journals.physiology.org/doi/abs/10.1152/jappl.1979.47.2.263
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