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Do you know if you have fast twitch or slow twitch muscle fibers? Genetically speaking, you probably have a combination of both, but most individuals will have a preponderance of one or the other. This often explains why some individuals excel at a particular sport while others do not. Consider this:
Do you have any friends who seem to be able to exercise for long periods of time without visible fatigue?
Have you ever watched a basketball game where one player is able to jump higher and gather in more rebounds than another?
Why can some individuals sprint down a football field in no time flat while others cannot?
What allows some individuals the ability to lift enormous amounts of weight, and in very short periods of time, without much effort?
Some variances can be attributed to physical training and nutrition, but a greater percentage of performance differences are due to the types of muscle fibers each individual has - fast twitch or slow.
SLOW TWITCH FIBERS:
Slow twitch fibers (Type I) are not very strong but they do have a high metabolic capacity for endurance. There is a longer “time-to-peak” tension in slow twitch muscle fibers than there is in fast twitch fibers. Slow twitch muscle fibers can do their thing over and over again without much fatigue. They are very resistant to cellular demands and have a greater ability to use oxygen to its fullest. Persons with a higher proportion of slow twitch muscle fibers typically become endurance athletes. Such persons learn to love running and jogging because they are good at.
FAST TWITCH FIBERS:
Fast twitch muscle fibers (Type II), on the other hand, are like tiny gunpowder factories ready to explode on demand. These powerful fibers can contract at blazing speeds and power, but they fatigue very quickly. Fast twitch muscle fibers enable a basketball player to propel high up in the air, a football player to throw the ball across a field, or a boxer to extend their arm with tremendous force. These are powerful and forceful activities unsustainable for long periods of time. Actions made possible by fast twitch muscle fiber predominance.
EXERCISE AND MUSCLE FIBER DISTRIBUTION
The big question is can exercise change a muscle fiber from fast to slow or slow to fast? Muscle biopsies confirm that the distribution of fiber type is genetic, however, performance capability of both types can be enhanced with exercise. It comes back to the theory of habitual use. “Use it or lose it.” If you perform endurance activities, you can increase the concentration of energy producing enzymes needed for endurance, but you cannot change the genetic make-up from fast twitch to slow. Likewise, if you lift weights on a regular basis, strength will improve on all levels, but the genetic distribution of fibers will stay the same. The key with exercise is variety! Well-rounded exercise programs should include activities that train both types of muscle fibers. Fast and slow!
Sprint Intervals Train fast-twitch fibers
Spinning Train both fast and slow fibers
Circuit Training Train both fast and slow fibers
Jogging / Walking Train slow-twitch fibers
Step Aerobics Some fast-twitch, mostly slow
Weight Lifting Mostly fast-twitch training, some slow
Leisure Biking Mostly slow-twitch
Gardening Fast and slow
Back to the original question: Which kind of muscle fibers do you have? You may not be ready for a marathon just yet, or able to hurl a baseball across a field, but you can train for either one with exercise! |
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