Document Detail

Muscle fiber type distribution as estimated by Cybex testing and by muscle biopsy.
MedLine Citation:
PMID:  8455452     Owner:  NLM     Status:  MEDLINE    
The purpose of the present study was to derive a regression equation relating variables obtained from a series of noninvasive functional tests in a normal subject population to the fiber type distribution of vastus lateralis muscle (VL) determined using muscle biopsy. All functional tests were designed to distinguish between basic properties of Type II fibers (fast twitch fibers) and Type I fibers (slow twitch fibers) and included assessment of peak torque, power output at nine different angular velocities (60 degrees.s-1 to 300 degrees.s-1), as well as a fatigue test consisting of 60 consecutive contractions at 90 degrees.s-1 to establish fatigue resistance of the knee extensor muscles. Using a stepwise multiple regression procedure, relative torque after 53-55 contractions (T55) in the fatigue test and power output at an angular velocity of 280 degrees.s-1 normalized for fat free mass of the thigh (FFMT) were the best predictors for fiber type distribution, explaining 51.8% of the variance in the proportion of Type II fibers in VL. No other measured variable met entering criteria. Subgroup analyses revealed a higher peak torque/FFMT, higher power/FFMT values at angular velocities of 200 degrees.s-1 and higher, and lower relative torque beyond 30 contractions in the fatigue test for the fast twitch group, FTG (subjects with > 60% Type II fibers, N = 8) as compared with the STG (subjects with < 45% Type II fibers, N = 9). Results from the present study suggest that two simple functional tests on a Cybex dynamometer yield reasonable estimates of the fiber type distribution in VL.
E Suter; W Herzog; J Sokolosky; J P Wiley; B R Macintosh
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Medicine and science in sports and exercise     Volume:  25     ISSN:  0195-9131     ISO Abbreviation:  Med Sci Sports Exerc     Publication Date:  1993 Mar 
Date Detail:
Created Date:  1993-04-20     Completed Date:  1993-04-20     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  363-70     Citation Subset:  IM; S    
Human Performance Laboratory, Faculty of Physical Education, University of Calgary, Canada.
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MeSH Terms
Analysis of Variance
Body Composition
Isometric Contraction / physiology
Leg / physiology
Models, Biological*
Multivariate Analysis
Muscle Contraction / physiology*
Muscles / anatomy & histology*,  physiology
Physical Exertion
Regression Analysis

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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