Beneficial effects of voluntary wheel-running on the properties of
dystrophic mouse muscle.
Hayes, Alan, and David A. Williams.
Muscle and Cell Physiology Laboratory, Department of Physiology,
The University of Melbourne, Parkville, Victoria, 3052, Australia
APStracts 2:0421A, 1995.
Effects of voluntary exercise on the isometric contractile, fatigue
and histochemical properties of hindlimb dystrophic (mdx and 129ReJ
dy/dy) skeletal muscles were investigated. Mice were allowed free
access to a voluntary running wheel at 4 weeks of age, for a duration
of 16 (mdx) or 5 (dy/dy) weeks. Running performance of mdx mice (4
km/day at 1.6 km/hr) was inferior to normal mice (6.5 km/day at 2.1
km/hr). However, exercise improved the force output (15%) and the
fatigue resistance of both C57BL/10 and mdx soleus muscles. These
changes coincided with increased proportions of smaller type I
fibers, and decreased proportions of larger type IIA fibers in the
mdx soleus. The extensor digitorum longus (EDL) of mdx, but not
normal, mice also exhibited improved resistance to fatigue and
conversions towards oxidative fiber types. The dy/dy animals were
capable of exercising, yet ran significantly less than normal animals
(0.5 km/day). Despite this, running increased the force output of the
plantaris muscle (50%). Taken together, the results showed that
exercise can have beneficial effects on dystrophic skeletal muscles.
Received 15 March 1995; accepted in final form 26 September 1995.
APS Manuscript Number A284-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95