Journal of Applied Physiology, Vol 67, Issue 1 123-127, Copyright © 1989 by American Physiological Society
NADH shuttle enzymes and cytochrome b5 reductase in human skeletal muscle: effect of strength training
P. G. Schantz and M. Kallman
Department of Physiology III, Karolinska Institute, Stockholm, Sweden.
The main aim of this study was to investigate whether enzyme levels of the
malate-aspartate and alpha-glycerophosphate shuttles and of cytochrome b5
reductase in human skeletal muscle are affected by strength training.
Muscle biopsy samples from the deltoid muscle of the nondominant arm in
untrained (n = 12) and strength-trained (n = 12) subjects were compared.
The strength-trained muscles were characterized by a tendency to a higher
percentage of type I fibers (67 vs. 59%), a lower percentage of type IIb
fibers (12 vs. 18%), 34% larger mean fiber areas, and 19% more capillaries
per fiber (P less than 0.1). No difference was noted in levels of enzymes
representing the citric acid cycle, fatty acid oxidation, and glycolysis,
nor in the number of capillaries per square millimeter. Neither did the
levels of malate-aspartate and alpha-glycerophosphate shuttle enzymes nor
cytochrome b5 reductase differ. Levels of cytochrome b5 reductase
correlated (r = 0.59, P less than 0.01) with levels of the mitochondrial
marker enzyme citrate synthase. It is concluded that strength training does
not appear to result in increased levels of NADH shuttle enzymes and
cytochrome b5 reductase.
