Effect of Treadmill Training on Muscle Oxidative
Capacity and Accretion
in Young Male Obese
and Nonobese Zucker Rats12
GORDON M. WARDLAW,3 MURRAY L. KAPLAN4 AND
SUSAN LANZA-JACOBY*
Department
of Food and Nutrition,
Iowa State University,
Ames,
IA 50011 and
'Department
of Surgery,
Jefferson
Medical College, Philadelphia,
PA 19107
ABSTRACT
This study was designed
to determine
if treadmill
training
of the
male obese Zucker
rat could reverse its deficit
in muscle accretion,
expose a possible
latent defect
in its muscle oxidative capacity
or significantly
alter
its food intake and
lipid deposition.
At 12 wk of age muscle mass and myofibrillar
protein concentration
were significantly
lower and body lipid and food intake were significantly
higher
in
the sedentary
obese than in the nonobese
rat. Exercise, by both inducing
hypophagia
and increasing
energy output,
led to a lower body weight,
body lipid,
and muscle
mass in the exercised
than
in the nonexercised
rats. This response
to exercise did not
differ between both phenotypes,
except for body lipid.
In that case the reduction
of
body lipid was greater
for the obese rats. Muscle mitochondrial
enzyme activities
and
rates of mitochondrial
respiration
in the obese rats were not different
or greater
than
those of their sedentary
or pair-exercised
nonobese counterparts.
Taken together
these
data
indicate
that oxidative
capacity
per unit of muscle
is not significantly
lower
in
the obese rats than
in nonobese
rats in both sedentary
and exercised states, but that
total muscle oxidative
capacity
is lower on a whole-animal
basis since total muscle
mass is lower. Further,
exercise
reduces,
but does not prevent
the enhanced
weight
gain and lipid accretion
that characterizes
the obese rat.
J. Nutr. 116: 1841-1852,
1986.
INDEXING KEY WORDS
treadmill
exercise
• Zucker
rat
• muscle mass
• enzyme activity
• mitochondria
The obese Zucker
rat exhibits
many
alter-
nonobese
rats.
Further,
Lanza-Jacoby
and
ations
in protein
metabolism
when
com-
Kaplan
(6) reported
that
stromal,
myofi