Multivariate genetic analysis of maximal isometric muscle force at
different elbow angles.
Thomis, Martine A., Marc Van Leemputte, Hermine H. Maes, Cameron J. R.
Blimkie, Albrecht L. Claessens, Guy Marchal, Eustachius Willems,
Robert F. Vlietinck, and Gaston P. Beunen.
Center for Physical Development Research, Dept. of Kinesiology,
Faculty of Physical Education and Physiotherapy, Katholieke
Universiteit Leuven, B-3001 Leuven, BELGIUM, Radiology Unit and
Center for Human Genetics, Faculty of Medicine, Katholieke
Universiteit Leuven, B-3000 Leuven, BELGIUM MCVirginia, Dept. of
Human Genetics, Virginia Commonwealth University VA 23298, Department
of Kinesiology, McMaster University, Hamilton, Ontario, Canada L8S
4K1
APStracts 3:0520A, 1996.
The maximal isometric moment at five different elbow joint angles was
measured in 25 monozygotic and 16 dizygotic male adult twin pairs
(22.4 +/- 3.7 yr.). Genetic model-fitting was used to quantify the
genetic and environmental contributions to individual differences in
isometric strength. Additive genetic factors explained 66 to 78% of
the variance in maximal torque at 170 degrees -140 degrees -110
degrees and 80 degrees flexion (extension=180 degrees ). At 50
degrees flexion, common and subject-specific environmental factors
contributed equally to the variation. The contribution of unique
environmental factors concurs with the level of variability in muscle
activation and (dis)-comfort of torque production in the specific
angle. The relative contribution of lever arm and force-length
relationship in torque varies according to the angle. Since these
factors might be genetic, this variability is reflected in the
genetic contribution at the extreme angles of 170 degrees and 50
degrees . Multivariate analyses suggested a general set of genes that
control muscle area and isometric strength, together with a more
specific strength factor. Genetic correlations were high (.82 - .99).
Genes responsible for arm segment lengths did not contribute to
muscle area, nor to isometric strength.
Received 3 September 1996; accepted in final form 22 October
1996.
APS Manuscript Number A851-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996