вторник, 8 августа 2017 г.

Легенда об определении типов волокон на основе повторений упражнения.


Начало: THORSTENSSON A., AND J. KARLSSON. Force velocity relations and fiber composition in human knee extensor muscles. J.Appl. Physiol. 40:12–16. 1976. И хотя её оспаривали CAMPBELL, C.J., A. BONEN, R.L. KIRBY, AND A.N. BELACASTRO. Muscle fiber composition and performance capacities of women. Med. Sci. Sports. 11:260–265. 1979.
Это тема продолжала будоражить умы, что привело в 1993 к созданию уравнения множественной регресии SUTER, E., W. HERZOG,J.SOKOLOSHY, J.P. WILEY, AND B.R. MACINTOSH. Muscle fiber type distribution as estimated by Cybex testing and by muscle biopsy. Med. Sci. Sports Exerc. 25:363–370. 1993. В котором на основе показателей изокинетического динамометра (оценивалось изолированное разгибание колена) и % тощей массы тела определяли преобладание одного из типов волокон))) с коэффициентом корреляции 0,72.
И что, думаете на этом всё? Нет, как птица Феникс метод возродился в исследовании Douris, P.C., B.P. White, R.R. Cullen, W.E. Keltz, J.Meli, D.M. Mondiello, and D. Wenger. The relationship betweenmaximal repetition performance and muscle fiber type as estimated by noninvasive technique in the quadriceps of untrained women. J. Strength Cond. Res. 20(3):699–703. 2006. Можно смело рассматривать, как научную деятельность не имеющую практического значения).
В то же время выходили статьи показывающие несостоятельность метода.
The purpose of this study was to evaluate the use of traditional resistance training equipment in the measurement of muscular power. This was accomplished by measuring the velocity of movement through a measured distance during maximal effort lifts using a Smith rack. The reliability of the method was established using 10 male volunteers who performed both bench press and squat exercises in a Smith rack. Maximal power output was determined at 30, 40, 50, 60, 70, 80, and 90% of the subject's 1 repetition maximum (1RM). Test-retest power values were not statistically different. Another 15 male volunteers who had previous muscle biopsy data from the vastus lateralis muscle performed the same maximal power output evaluation. There were no significant relationships between peak power outputs and fiber-type expressions when linear regressions were performed. The power curve produced by graphing power output vs. the percentage of 1RM indicates that peak power output occurs between 50 and 70% of 1RM for the squat and between 40 and 60% of 1RM for the bench press. These data indicate that this method of evaluation of muscle power is reliable, although it is not predictive of muscle fiber-type percentages.
SIEGEL, JUDITH A.; GILDERS, ROGER M.; STARON, ROBERT S.; HAGERMAN, FREDRICK C. Human Muscle Power Output During Upper-and Lower-Body Exercises. Journal of Strength & Conditioning Research. 16 (2):173-178, May 2002.
Выводы исследования:Muscle Fiber Characteristics and Performance Correlates of Male Olympic-Style Weightlifters FRY, ANDREW C.; SCHILLING, BRIAN K.; STARON, ROBERT S.; HAGERMAN, FREDRICK C.; HIKIDA, ROBERT S.; THRUSH, JOHN T.Journal of Strength & Conditioning Research. 17(4):746-754, November 2003.
...successful weightlifting performance is not dependent on IIB fibers, and that weightlifters exhibit large percentages of type IIA muscle fibers and MHC IIa isoform content. 
В общем, ждём неинвазивного метода определения дальше, а когда дождёмся, возможно выясним практическое значение этого знания.

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