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Exercise and myocardial tolerance to ischaemia-reperfusion
S L Lennon1, J C Quindry, J P French
1Department of Applied Physiology and Kinesiology, Center for Exercise Science, University of Florida, Gainesville, FL 32611, USA.
Unlabelled:
It is well established that both short-term (1-5 days) and long-term (weeks to months) high intensity exercise (i.e. 70-75%VO2max) provides cardioprotection against ischaemia-reperfusion injury. However, it is unclear if moderate intensity exercise will also provide cardioprotection.
Aim:
Therefore, these experiments compared the protective effects of moderate vs. high intensity exercise in providing defense against ischaemia-reperfusion injury.
Methods:
Male Sprague-Dawley rats were randomly assigned to one of three-experimental groups: (1) sedentary (control); (2) moderate intensity treadmill exercise (60 min day(-1) at approximately 55%VO2max); or (3) high intensity treadmill exercise (60 min day(-1) at approximately 75%VO2max). Hearts were exposed to 20 min of global ischaemia followed by 30 min reperfusion in an isolated working heart preparation.
Results:
Compared with sedentary rats, both moderate and high intensity exercised rats maintained a higher (P < 0.05) percentage of pre-ischaemia cardiac output and cardiac work (cardiac output x systolic blood pressure) during reperfusion. No differences in the percent recovery of cardiac output and heart work existed (P > 0.05) between the two exercise groups.
Conclusions:
These data reveal that both moderate and high intensity exercise training provide equivalent protection against ischaemia-reperfusion injury.