Protective Effects of Accumulated Aerobic Exercise in Infarcted Old Rats

Abstract Background: Aerobic exercise exerts cardioprotective effects on myocardial infarction. However, there is lack of information about the possible protective effects of continuous or accumulated aerobic exercise performed prior to myocardial infarction in aging. Objective: To evaluate the preventive effects of continuous or accumulated aerobic exercise on physical capacity, pulmonary congestion and ventricular weight in rats submitted to myocardial infarction. Methods: Old male Wistar rats were divided into four groups: sham control, sedentary infarcted, continuous aerobic exercise submitted to myocardial infarction, and accumulated aerobic exercise submitted to myocardial infarction. Body weight and maximum speed were evaluated at the beginning and at the end of the protocol. Trained groups performed continuous (1 h a day) or accumulated (30 minutes in the morning and 30 minutes in the afternoon) exercise. All groups, except the sham control, were submitted to myocardial infarction surgery at the end of the protocol. Heart, skeletal muscles, as well as wet and dry lung were weighed. The significance level in statistical analysis was established at p < 0.05. Results: Both continuous and accumulated exercise caused an increase in physical capacity in rats, as well as prevented its further impairment after myocardial infarction, and in the accumulated exercise group this prevention was greater. The continuous exercise group demonstrated an increase in lung water content, while the accumulated exercise group presented a reduction in body weight and an increase in left ventricle relative weight. Conclusion: In conclusion, the data of the present study indicate that accumulated aerobic exercise present a better protective effect than continuous aerobic training in the context of myocardial infarction and aging.

摘要 背景：有氧运动对心肌梗死（myocardial infarction）具有心脏保护作用。然而，针对衰老个体在心肌梗死前实施的持续性或累积性有氧运动的潜在保护效应，目前仍缺乏相关研究数据。
研究目的：评估持续性或累积性有氧运动对心肌梗死模型大鼠的体适能、肺充血及心室重量的预防保护作用。
实验方法：将老年雄性Wistar大鼠分为四组：假手术对照组、久坐心肌梗死造模组、持续性有氧运动心肌梗死造模组以及累积性有氧运动心肌梗死造模组。在实验方案启动与结束阶段，分别测定大鼠体重与最大运动速度。训练组分别实施持续性训练（每日1小时）或累积性训练（上午30分钟、下午30分钟）。除假手术对照组外，其余各组均在实验方案结束时接受心肌梗死手术造模。称量心脏、骨骼肌以及肺脏的湿重与干重。统计学分析的显著性水平设定为p < 0.05。
实验结果：持续性与累积性有氧运动均可提升大鼠体适能，并可阻止心肌梗死后体适能进一步下降；其中累积性有氧运动组的保护效果更为显著。持续性有氧运动组大鼠肺脏含水量升高，而累积性有氧运动组大鼠体重降低、左心室相对重量升高。
研究结论：本研究数据表明，在衰老合并心肌梗死的模型中，累积性有氧运动的心脏保护效果优于持续性有氧运动训练。