Efeitos musculares promovidos pelo treinamento resistido em ratas ovariectomizadas
Abstract
Menopause is highly associated with the increase of several metabolic disorders. In
addition menopause promotes accelerated loss of muscle strength and mass, process
known as sarcopenia, generating a deleterious role in the performance of physical
functions. In this sense, resistance training has been recommended for the treatment of
numerous diseases associated with menopause, as well as sarcopenia, as a nonpharmacological
intervention. The aim of this study was to investigate the effects of the
resistance training using the vertical ladder as a model on the muscle cross-sectional
area and the percentage of muscle fiber types in the plantaris muscle of intact or
ovariectomized rats and/or under hormone reposition therapy. Holztman adult female
rats were distributed in 7 groups: Sham operated sedentary (Sham-Sed), Sham operated
resistance trained (Sham-Tr), Ovariectomized sedentary (Ovx-Sed), Ovariectomized
resistance trained and hormone reposition (Ovx-Tr-TRH), Ovariectomized sedentary
and hormone reposition (Ovx-TRH), Ovariectomized resistance trained (Ovx-Tr),
Ovariectomized and placebo reposition (Ovx-TRH-Pl). During a 12-week resistance
training the animals climbed the vertical ladder of 1.1m with weights attached to their
tails. Each session was carried out every 72 hours with 4-9 climbs. The ovariectomy
promoted a reduction in cross-sectional area of the type I and II fiber when compared to
Sham-Sed group, whereas the resistance training in the ovariectomy (Ovx-Tr group)
was able to increase the cross-sectional area of the two fiber types (p<0.05). Moreover,
TRH did not prevent the reduction of cross-sectional area of the type II fiber however it
attenuated the reduction in cross-sectional area of type I fiber. The ovariectomy,
hormone reposition and resistance training had no effect into promote alterations in the
absolute number of muscle fiber types of the plantaris muscle and there was no
correlation in the percentage of fiber muscle types. Our results indicate that resistance
training can be a useful tool to prevent skeletal muscle mass reduction induced by
ovariectomy.