Ds. O'Neill et al., Effect of endurance exercise on myosin heavy chain gene regulation in human skeletal muscle, AM J P-REG, 45(2), 1999, pp. R414-R419
Citations number
24
Categorie Soggetti
Physiology
Journal title
AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY
The purpose of this study was to determine the effect of endurance-oriented
exercise on myosin heavy chain (MHC) isoform regulation in human skeletal
muscle. Exercise consisted of 1 h of cycle ergometer work per day at 75% ma
ximal oxygen consumption for seven consecutive days. Muscle was obtained be
fore the first bout of exercise, 3 h after the first bout of exercise, and
before and 3 h after the final exercise bout on day 7 (n = 9 subjects). No
changes in MHC mRNA (I, IIa, IIx) were evident after the first exercise per
iod. There was, however, a significant (P < 0.05) decline (-30%) in MHC IIx
mRNA 3 h after the final training bout. An interesting finding was that a
higher pretraining level of MHC IIx mRNA was associated with a greater decl
ine in the transcript before (r = 0.68, P < 0.05) and 3 h after (r = 0.82,
P < 0.05) the final exercise bout. These findings suggest that MHC IH mRNA
is downregulated during the early phase of endurance-oriented exercise trai
ning in human skeletal muscle but only after repeated contractile activity.
Pretraining MHC IIx mRNA content may influence the magnitude of this respo
nse.