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cardiac remodelling are still necessary. Figure 9.2 summarizes the main positive
effects of ET in experimental MI.
6 Exercise Training and MI Associated with Chronic
Diseases or Conditions
MI can be associated with other pathophysiological conditions which are usually
present previously to the cardiac event, acting, indeed, as a MI risk factor or as
additional complication factors after MI.
6.1 Menopause
Menopause is characterized by several hormonal alterations in adult women, mainly
in the estrogen levels, which declines around 60% [ 43 ]. Since estrogen is strongly
associated with endothelial function, fat deposition, inhibition of vascular smooth
cells growing, among others, its decrease during menopause collaborate to increase
the cardiovascular risk during this period [ 44 ]. In fact, during this phase of life,
women commonly show high blood pressure values, increased intima-media thick-
ness of the carotid and femoral arteries, increased arterial stiffness, as well as
impairment of flow-mediated vasodilation [ 45 ]. Therefore, menopausal women
show elevated risk to suffer from MI [ 46 , 47 ]. Lifestyle changes, including the prac-
tice of ET, have been strongly suggested to this population, in an attempt to mitigate
the risks and comorbidities associated with menopause [ 48 ].
In this sense, some experiments have been designed to identify the impact of ETon menopausal MI rats. In the experiment of Almeida et al. [ 47 ], authors underwent
ovariectomized (OVX) rats to MI and, 2 weeks later, started ET. The protocol of
exercise occurred 5 days per week, during 8 weeks. Results did not demonstrate
effectiveness of ET to alter MI extension. Therefore, MI extension was similar
between OVX MI sedentary and trained rats. Fluorescence analyses indicated that
SOD production was increased in the heart of MI rats. However, ET could prevent
this alteration. Protein expression of components of the RAAS system (i.e., AT1
receptor) was increased in the heart of ovariectomized MI rats when compared to
sham group. However, ET decreased the expression of these proteins, as well as
increased catalase. Lastly, ET decreased collagen deposition in the left ventricle,
which was high in OVX MI rats [ 47 ]. Taken together, these data indicate that ET
could modulate pathways associated with cardiac remodelling. However, the absence
of a morphological alteration (i.e., MI) could indicate that, to this population, ET
program must be different, using, for example, a longer time of intervention.
Nevertheless, another study, which also underwent OVX MI rats to ET, showedimproved BrS, cardiac autonomic control and resting bradycardia in the animals
9 Myocardial Infarction and Exercise Training: Evidence from Basic Science