Muscle Fiber Characteristics Of Weightlifters and Powerlifters

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The below may be of interest:

Muscle Fiber Characteristics and Performance Correlates of Male

Olympic-Style Weightlifters. The Journal of Strength and Conditioning

Research: Vol. 17, No. 4, pp. 746–754

C. Fry, K. Schilling, S. Staron, Fredrick C.

Hagerman, S. Hikida and T. Thrush. 2003:

Biopsies from the vastus lateralis muscle of male weightlifters (WL;

n = 6; ± SE, age = 27.0 ± 2.1 years), and non–weight-trained men

(CON; n = 7; age = 22.0 ± 2.0) were compared for fiber types, myosin

heavy chain (MHC) and titin content, and fiber type–specific

capillary density. Differences (p < 0.05) were observed for percent

fiber types IIC (WL = 0.4 ± 0.2, CON = 2.4 ± 0.8); IIA (WL = 50.5 ±

3.2, CON = 26.9 ± 3.7); and IIB (WL = 1.7 ± 1.4, CON = 21.0 ± 5.3),

as well as percent MHC IIa (WL = 65.3 ± 2.4, CON = 52.1 ± 4.2) and

percent MHC IIb (WL = 0.9 ± 0.9, CON = 18.2 ± 6.1). All WL exhibited

only the titin-1 isoform. Capillary density (caps·mm & #8722;2) for all fiber

types combined was greater for the CON subjects (WL = 192.7 ± 17.3;

CON = 262.9 ± 26.3), due primarily to a greater capillary density in

the IIA fibers. Weightlifting performances and vertical jump power

were correlated with type II fiber characteristics.

These results suggest that 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.

The muscle characteristics contributing most to weightlifting performances

appear to be the percent IIA fibers and the percent area of IIA fibers. Two

points should be made here: (1) type IIB fibers were practically nonexistent in

the WL, and (2) the percentage of type I fibers were not significantly different

from the CON subjects. This indicates that for the weightlifters used in the

present study, the percent of fibers (i.e., type I vs. type II) is not as

critical as the percent fiber type area (i.e., percent area type I vs. percent

area type IIA vs. percent area type IIB)... successful weightlifting

performances are dependent on possessing a high percentage of type IIA fibers

and a low percentage of type IIB fibers.

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Muscle Fiber Characteristics of Competitive Power Lifters. The

Journal of Strength and Conditioning Research: Vol. 17, No. 2, pp.

402–410

C. Fry, M. Webber, Lawrence W. Weiss, P. Harber,

Mark Vaczi and A. Pattison. 2003:

To examine the skeletal muscle characteristics of power lifters, 5

competitive power lifters (PL; ± SE; age = 31.0 ± 1.5 years, squat =

287.7 ± 15.7 kg, bench press = 170.5 ± 17.7 kg, and deadlift = 284.2

± 7.5 kg) and 5 untrained control subjects (CON; age = 27.3 ± 3.3

years) served as subjects. Isokinetic squat force and power was

greater (p < 0.05) for the PL at all bar velocities (0.20, 0.82, and

1.43 m ;pd s & #8722;1), as was vertical jump height and estimated power.

Muscle biopsies from the vastus lateralis m. revealed significant

differences for percent fiber type (PL, IIA = 45.5 ± 1.6%, IIB = 1.3

± 0.8%; CON, IIA = 33.4 ± 3.1%, IIB = 12.0 ± 2.4%); percent fiber

type area (PL, IIA = 51.8 ± 1.6%, IIB = 1.3 ± 0.8%; CON, IIA = 43.5 ±

3.4%, IIB = 12.4 ± 2.6%); and percent myosin heavy chain isoform (PL,

IIa = 59.5 ± 6.1%; CON, 46.5 ± 2.5%).

Muscle fiber characteristics were significantly correlated (r = ±

0.61) with numerous strength and power measures for the PL. These

data illustrate the muscle fiber characteristics necessary for the

maximal force production requirements of power lifting.

Based on the data presented, the muscle characteristics contributing

most to successful power lifting performances appear to be (a)

greater percentage of IIA fibers, percentage area of IIA fibers, and

percentage of MHC IIa, and ( a lesser percentage of IIB fibers and

percentage area of IIB fibers. The fiber characteristics exhibited by

the PL were significantly correlated to numerous muscle strength and

power measures.

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Any additional studies?

Carruthers

Wakefield, UK