E FIBER TYPE The human skeletal muscle system is made up of a combination of

E fiber type the human skeletal muscle system is made

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E.) FIBER TYPE The human skeletal muscle system is made up of a combination of slower twitch muscle fibers and faster twitch muscle fibers. Faster twitch fibers
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Chapter No. 5 Scientific Principles of Strength Training P 140 contract at faster velocities, respond better to heavy resistance training (grow more), and generate higher forces. Slower twitch fibers contract at slower velocities, respond more poorly to heavy resistance training (grow less), and generate lower forces. But because they generate lower forces, are more well vascularized, and for several other reasons, slower twitch fibers take on less homeostatic damage than faster twitch fibers and heal much quicker. Muscle groups with a higher proportion of faster twitch fibers take longer to heal, and those with a higher proportion of slower twitch fibers heal more quickly. The muscles of the upper body tend to be faster twitch (on average) that those of the lower body (specifically the quads and glutes), which may explain while the squat is a bit more fatigue resistant than we would come to expect based solely on weight lifted and ROM. Interestingly, the hamstrings are notoriously fast-twitch dominant in most people, which may explain, in addition to the great use of upper body musculature as well, why the deadlift is so fatiguing. In addition to lift or body part specificity in fiber type, different individuals have varied fiber type averages. If we take all of the muscles of the human skeletal muscle system, one individual may be 60% faster twitch and 40% slower twitch, while another might have the opposite ratio. Those individuals with faster fibers will tend to be able to generate and hold onto more fatigue, while those with slower fiber types have a gigantic work capacity and recovery ability, so will be able to dissipate fatigue rapidly as well as have very high MRVs. Though in a bit of irony, those same slower twitch individuals tend to experience less success in their results because of the poor adaptive nature of their dominant fibers to heavy resistance training.
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Chapter No. 5 Scientific Principles of Strength Training P 141 F.) GENDER Females have two unique physiological advantages in fatigue dissipation just because they are female. • Female musculature tends to be more highly vascularized and thus may recover faster. • Females are more rarely found at the extremes of fiber type ratio. In a sport such as powerlifting that attracts the fast- twitch extremes, most females will be clustered closer to an even mix of fast and slow fibers than the males, though of course it comes down to the fiber type of each individual male or female. This means that females will gain a slight
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Chapter No. 5 Scientific Principles of Strength Training P 142 advantage in the proclivity to generate less homeostatic damage and recover faster than males.
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