Bear Strength

[Panther]

Muscle Fiber Characteristics of Competitive Power Lifters

"MHC I being the slowest to contract and MHC IIb being the fastest. With this being the case, it is sometimes suggested that type IIB fibers are desirable for strength and power. However, current literature suggests that these fibers convert to type IIA regardless of what type of physical activity they are
engaged in (4, 10, 14, 38, 39, 40).

Previous investigations of competitive lifters (i.e.,
power lifters and Olympic-style weightlifters) have determined that 53–60% of the muscle fibers in the vastus lateralis are type II, which are sometimes referred to as fast twitch (18–20). Among untrained men, fiber-type percentages are not always related to physical performances (26, 28), which is not unreasonable since many physical performance tasks require contribu-
tions from a large number of physiological systems
and are not dependent on just fiber-type percentages.
On the other hand, isokinetic strength has been suc-
cessfully used as a predictor of fast- and slow-twitch
fiber percentages (45). What may be more important
are the actual cross-sectional areas of each of the major
fiber types. In men, type II fibers typically comprise a
larger cross-sectional area (38). When competitive lifters have been studied, the areas of type II fibers are approximately 8,000 mm2, whereas type I fibers are approximately 5,000 mm2 (10, 42–44). It has been suggested that competitive strength performances may be positively affected when the cross-sectional areas of type II fibers equals 60–90% (25). This investigation
will determine if such a relationship is present. It is
hypothesized that the unique training characteristics
of power lifters will produce distinct differences in the physiological characteristics of skeletal muscle when compared with not only untrained subjects, but also
to strength athletes in other sports."

"The PL exhibited a greater percentage of MHC IIa compared with CON, although the percentage of MHC IIb was not significantly different. The PL exhibited a similar percentage of MHC IIa as that of
weightlifters but a much larger percentage of MHC IIb (male weightlifters, X¯ 6 SE; MHC IIa 5 64.0 6 2.3%; MHC IIb 5 1.4 6 1.4%; 14). Such differences could be due to the functional requirements of the respective sports, or due to the training status of the subjects at the time of the biopsy. "

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