Exercise for Cardiovascular Disease Prevention and Treatment From Molecular to Clinical, Part 1

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It is important to mention that mice from Bito et al. [ 27 ] ran in a larger average

daily distance (~11  km/day) than animals from Puhl et  al. (~5  km/day) [ 28 ].

However, animals from Puhl et al. [ 28 ] ran during 10 weeks versus 8 weeks from

Bito et al. [ 27 ]. Therefore, more evidence about the effects of PA on experimental

MI are still necessary. Figure 9.1 depicts the main alterations induced by PA in

experimental models of MI.

5 Exercise Training and Myocardial Infarction

As aforementioned, ET has been used as a powerful tool in cardiac rehabilitation

programs, collaborating to improve prognosis, once its practice can revert some

impairments observed after MI. Either aerobic (endurance) and resistance ET can

be prescribed as part of the rehabilitation program. Nevertheless, the majority of the

experimental studies were conducted having the aerobic training (performed on a

treadmill) as choice. This may be due to a higher similarity to cardiac rehabilitation

programs for humans, as aerobic training is predominant. Other methods of ET have

also been studied in experimental models of MI as detailed in this section.

The benefits of ET on cardiac remodelling seem to occur in both phases: early and

late. The early remodelling phase is characterized by the expansion of the infarcted

area induced by degradation of the structural collagen presented in the extracellular

matrix (ECM) by MMPs, which are secreted by the immune cells in response to

MI-induced inflammation [ 8 , 29 ]. In addition, in an attempt to preserve cardiac out-

infarcted

heart

 Cardiomyocyte

width

̄ Cardiomyocyte

shortening

̄ Calcium handling

 Heart weight

 Collagen content

 Scar formation

 MMP

 PICs

Cardiac

functioning

Ineffectiveness

Inhibition

Cardiac

remodelling

PHYSICAL

ACTIVITY

Fig. 9.1 Main effects of physical activity (PA) in experimental myocardial infarction (MI). In
rodents, PA can be studied using a voluntary running wheel where animals can exercise. MMP
matrix metalloproteinases, PICs proinflammatory citokynes

I.C. Moraes-Silva et al.