Role of four-week resistance exercise in preserving the heart against ischaemia-reperfusion-induced injury.

OBJECTIVE: We studied the cardioprotective effect of resistance training against ischaemia-reperfusion-induced injury. METHODS: Forty male rats were divided into trained and sedentary groups (n = 20 for each). The trained rats were exercised at 12 repetitions/set, four sets/day and five days/week for four weeks. Transient regional ischaemia of the left anterior descending coronary artery (40 min) was followed by 80 min of reperfusion. RESULTS: Baseline developed and diastolic pressures and coronary flow were similar in the two groups. While diastolic pressure increased and developed pressure and coronary flow decreased in both the ischaemic and perfusion periods (as indices of cardiac damage), there were no statistically significant differences between the trained and sedentary groups in these parameters. Resistance training did not significantly change the infarct size and apoptosis rate. CONCLUSION: We did not see a cardioprotective effect of resistance exercise against ischaemia-reperfusion-induced injury in this study. A precise conclusion about this issue needs more investigations.

Long-term exercise training affects age-induced changes in HSP70 and apoptosis in rat heart.

The aim of this study was to test the effects of age and long-term exercise training on antioxidant, heat shock protein 70 (HSP70) expression and apoptosis by comparing the hearts of sedentary and trained rats. Training groups went under 3-, 6- and 9-months of regular exercise (25 m/min with a 0% slope, 60 min/day and 6 days/week). Level of glutathione increased with age in trained and sedentary control rats but level of this factor unchanged by training. Activity of mitochondrial superoxide dismutase (mtSOD) increased in heart homogenates of 6- and 9-months trained animals as compared with their sedentary. The rates of apoptosis were increased with age but level of apoptosis in 9-months trained group was significantly lower than corresponding sedentary. Levels of HSP70 expression were significantly decreased with age while long-term training induced marked increase in HSP70 expression levels. These results show that a long-term regular exercise affects age-induced changes in mtSOD, HSP70 and apoptosis as it increases mtSOD activities and HSP70 expression levels and elicits a marked reduction in apoptosis rate in rat myocardium. However, a shorter training program is not effective.