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

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2  h of reperfusion. In addition, Powers et  al. [ 6 ] showed that, compared with

untrained, exercised animals kept a higher systolic blood pressure throughout

regional ischemia and reperfusion protocol after a 10-week endurance exercise train-

ing program.

Apart from these data, several other studies have underpinned that long-term

exercise benefits the heart against all three levels of IRI [ 22 , 67 , 68 , 78 – 81 ].

However, a criticism exists - most studies applied ischemia within 48 h after the last

exercise session [ 6 , 67 , 78 , 80 , 81 ] and acute bouts of exercise have been demon-

strated to protect the heart against IRI for at least 48 h [ 12 ]. Therefore, this choice

of interval between the last exercise bout and ischemia may have jeopardized the

assessment of cardioprotection afforded exclusively by chronic training.

4.2 Short-Term Exercise

After the first evidence in the late 1970s that exercise training for several weeks

provided cardioprotection against coronary occlusion [ 76 ], investigating the cardio-

protective effect of acute exercise was just a matter of time. Discovering if an intrin-

sic cardioprotective response could be rapidly acquired had crucial impact to

understand the underlying mechanism and the exercise “dosage” required for opti-

mum protection [ 8 ].

In this sense, Locke et al. [ 82 ], using the retrograde perfused Langendorff heart

preparation, observed that rats exercising for only three consecutive days also had

improved post-ischemic developed pressure following IRI. However, just a single

bout did not change any measure of post-ischemic cardiac function. Data from

Yamashita et al. [ 12 ] partially concur with the results found by Locke et al. In this

study, untrained rats and those exercised for a single bout of 30 min at 30 m/min

were submitted to regional ischemia and reperfusion. The authors have demon-

strated that the rate–pressure product showed no significant difference among the

groups after 20 min of ischemia or 30 min after reperfusion. However, exercised rats

exhibited a marked decrease relative to control in the size of myocardial infarct.

On the other hand, Taylor et al. [ 8 ] after submitting 1 and 3 days trained rats to

IRI found that cardiac output of both groups was equally superior than untrained

rats. Several differences between the adopted experimental protocols in these stud-

ies, especially regarding the measured outcomes, ischemia/reperfusion protocol or

exercise duration and intensity, could account for the discrepancy seen in the results.

Nonetheless, although some authors advocate the opposite [ 82 ], most studies argue

that a single exercise session would be enough to provide some degree of cardiopro-

tection against IRI [ 8 , 12 ]. It is clearer, however, that at least three consecutive

exercise sessions benefit the heart against IRI, as data in this sense accumulates in

the literature [ 7 , 10 , 11 , 77 , 83 ].

The question that remains to be answered is whether short-term exercise provide

cardioprotection against IRI just as effective as long-term exercise or not. Despite

the lack of interventional settings focused in this specific matter, previous reviews

J.P. Borges and K. da Silva Verdoorn