Format

Send to

Choose Destination
See comment in PubMed Commons below
J Physiol. 2006 Nov 1;576(Pt 3):913-22. Epub 2006 Aug 17.

Change in contractile properties of human muscle in relationship to the loss of power and slowing of relaxation seen with fatigue.

Author information

1
School of Sport and Exercise Sciences, University of Birmingham, Birmingham B15 2TT, UK. d.a.jones@bham.ac.uk

Abstract

Slow relaxation from an isometric contraction is characteristic of acutely fatigued muscle and is associated with a decrease in the maximum velocity of unloaded shortening (V(max)) and both these phenomena might be due to a decreased rate of cross bridge detachment. We have compared the change in relaxation rate with that of various parameters of the force-velocity relationship over the course of an ischaemic series of fatiguing contractions and subsequent recovery using the human adductor pollicis muscle working in vivo at approximately 37 degrees C in nine healthy young subjects. Maximal isometric force (F(0)) decreased from 91.0 +/- 1.9 to 58.3 +/- 3.5 N (mean +/- s.e.m.). Maximum power decreased from 53.6 +/- 4.0 to 17.7 +/- 1.2 (arbitrary units) while relaxation rate declined from -10.3 +/- 0.38 to -2.56 +/- 0.29 s(-1). V(max) showed a smaller relative change from 673 +/- 20 to 560 +/- 46 deg s(-1) and with a time course that differed markedly from that of slowing of relaxation, showing very little change until late in the series of contractions. Curvature of the force-velocity relationship increased (a/F(0) decreasing from 0.22 +/- 0.02 to 0.11 +/- 0.02) with fatigue and with a time course that was similar to that of the loss of power and the slowing of relaxation. It is concluded that for human muscle working at a normal physiological temperature the change in curvature of the force-velocity relationship with fatigue is a major cause of loss of power and may share a common underlying mechanism with the slowing of relaxation from an isometric contraction.

PMID:
16916911
PMCID:
PMC1890410
DOI:
10.1113/jphysiol.2006.116343
[Indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Wiley Icon for PubMed Central
    Loading ...
    Support Center