Muscle fiber number in biceps brachii in bodybuilders and control subjects

J. D. MacDougall, D. G. Sale, Stephen Alway, J. R. Sutton

Research output: Contribution to journalArticle

104 Citations (Scopus)

Abstract

Muscle fiber numbers were estimated in vivo in biceps brachii in 5 elite male bodybuilders, 7 intermediate caliber bodybuilders, and 13 age-matched controls. Mean fiber area and collagen volume density were calculated from needle biopsies and muscle cross-sectional area by computerized tomographic scanning. Contralateral measurements in a subsample of seven subjects indicated the method for estimation of fiber numbers to have adequate reliability. There was a wide interindividual range for fiber numbers in biceps (172,085-418,884), but despite large differences in muscle size both bodybuilder groups possessed the same number of muscle fibers as the group of untrained controls. Although there was a high correlation between average cross-sectional fiber area and total muscle cross-sectional area within each group, many of the subjects with the largest muscles also tended to have a large number of fibers. Since there were equally well-trained subjects with fewer than normal fiber numbers, we interpret this finding to be due to genetic endowment rather than to training-induced hyperplasia. The proportion of muscle comprised of connective and other noncontractile tissue was the same for all subjects (~13%), thus indicating greater absolute amounts of connective tissue in the trained subjects. We conclude that in humans, heavy resistance training directed toward achieving maximum size in skeletal muscle does not result in an increase in fiber numbers.

Original languageEnglish (US)
Pages (from-to)1399-1403
Number of pages5
JournalJournal of Applied Physiology Respiratory Environmental and Exercise Physiology
Volume57
Issue number5
StatePublished - Dec 1 1984
Externally publishedYes

Fingerprint

Muscles
Resistance Training
Needle Biopsy
Financial Management
Connective Tissue
Hyperplasia
Skeletal Muscle
Collagen
Control Groups

All Science Journal Classification (ASJC) codes

  • Physiology
  • Endocrinology

Cite this

Muscle fiber number in biceps brachii in bodybuilders and control subjects. / MacDougall, J. D.; Sale, D. G.; Alway, Stephen; Sutton, J. R.

In: Journal of Applied Physiology Respiratory Environmental and Exercise Physiology, Vol. 57, No. 5, 01.12.1984, p. 1399-1403.

Research output: Contribution to journalArticle

@article{32a4f7014b22460e921d776e002cd11b,
title = "Muscle fiber number in biceps brachii in bodybuilders and control subjects",
abstract = "Muscle fiber numbers were estimated in vivo in biceps brachii in 5 elite male bodybuilders, 7 intermediate caliber bodybuilders, and 13 age-matched controls. Mean fiber area and collagen volume density were calculated from needle biopsies and muscle cross-sectional area by computerized tomographic scanning. Contralateral measurements in a subsample of seven subjects indicated the method for estimation of fiber numbers to have adequate reliability. There was a wide interindividual range for fiber numbers in biceps (172,085-418,884), but despite large differences in muscle size both bodybuilder groups possessed the same number of muscle fibers as the group of untrained controls. Although there was a high correlation between average cross-sectional fiber area and total muscle cross-sectional area within each group, many of the subjects with the largest muscles also tended to have a large number of fibers. Since there were equally well-trained subjects with fewer than normal fiber numbers, we interpret this finding to be due to genetic endowment rather than to training-induced hyperplasia. The proportion of muscle comprised of connective and other noncontractile tissue was the same for all subjects (~13{\%}), thus indicating greater absolute amounts of connective tissue in the trained subjects. We conclude that in humans, heavy resistance training directed toward achieving maximum size in skeletal muscle does not result in an increase in fiber numbers.",
author = "MacDougall, {J. D.} and Sale, {D. G.} and Stephen Alway and Sutton, {J. R.}",
year = "1984",
month = "12",
day = "1",
language = "English (US)",
volume = "57",
pages = "1399--1403",
journal = "Journal of Applied Physiology",
issn = "8750-7587",
publisher = "American Physiological Society",
number = "5",

}

TY - JOUR

T1 - Muscle fiber number in biceps brachii in bodybuilders and control subjects

AU - MacDougall, J. D.

AU - Sale, D. G.

AU - Alway, Stephen

AU - Sutton, J. R.

PY - 1984/12/1

Y1 - 1984/12/1

N2 - Muscle fiber numbers were estimated in vivo in biceps brachii in 5 elite male bodybuilders, 7 intermediate caliber bodybuilders, and 13 age-matched controls. Mean fiber area and collagen volume density were calculated from needle biopsies and muscle cross-sectional area by computerized tomographic scanning. Contralateral measurements in a subsample of seven subjects indicated the method for estimation of fiber numbers to have adequate reliability. There was a wide interindividual range for fiber numbers in biceps (172,085-418,884), but despite large differences in muscle size both bodybuilder groups possessed the same number of muscle fibers as the group of untrained controls. Although there was a high correlation between average cross-sectional fiber area and total muscle cross-sectional area within each group, many of the subjects with the largest muscles also tended to have a large number of fibers. Since there were equally well-trained subjects with fewer than normal fiber numbers, we interpret this finding to be due to genetic endowment rather than to training-induced hyperplasia. The proportion of muscle comprised of connective and other noncontractile tissue was the same for all subjects (~13%), thus indicating greater absolute amounts of connective tissue in the trained subjects. We conclude that in humans, heavy resistance training directed toward achieving maximum size in skeletal muscle does not result in an increase in fiber numbers.

AB - Muscle fiber numbers were estimated in vivo in biceps brachii in 5 elite male bodybuilders, 7 intermediate caliber bodybuilders, and 13 age-matched controls. Mean fiber area and collagen volume density were calculated from needle biopsies and muscle cross-sectional area by computerized tomographic scanning. Contralateral measurements in a subsample of seven subjects indicated the method for estimation of fiber numbers to have adequate reliability. There was a wide interindividual range for fiber numbers in biceps (172,085-418,884), but despite large differences in muscle size both bodybuilder groups possessed the same number of muscle fibers as the group of untrained controls. Although there was a high correlation between average cross-sectional fiber area and total muscle cross-sectional area within each group, many of the subjects with the largest muscles also tended to have a large number of fibers. Since there were equally well-trained subjects with fewer than normal fiber numbers, we interpret this finding to be due to genetic endowment rather than to training-induced hyperplasia. The proportion of muscle comprised of connective and other noncontractile tissue was the same for all subjects (~13%), thus indicating greater absolute amounts of connective tissue in the trained subjects. We conclude that in humans, heavy resistance training directed toward achieving maximum size in skeletal muscle does not result in an increase in fiber numbers.

UR - http://www.scopus.com/inward/record.url?scp=0021686799&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0021686799&partnerID=8YFLogxK

M3 - Article

VL - 57

SP - 1399

EP - 1403

JO - Journal of Applied Physiology

JF - Journal of Applied Physiology

SN - 8750-7587

IS - 5

ER -