Laboratory of Physical Activity and Health Promotion, Institute of Physical Education and Sports, University of Rio de Janeiro State, Rio de Janeiro, RJ, Brazil; Laboratory of Cardiovascular Investigation, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro, RJ, Brazil.
Laboratory of Morphological and Metabolic Analyses, Department of Morphology, Biomedical Institute, Fluminense Federal University, Niteroi, RJ, Brazil; National Institute for Science and Technology - INCT (In)activity and Exercise, CNPq - Niteroi, RJ, Brazil; Department of Morphology, Biomedical Institute, Fluminense Federal University, Niteroi, RJ, Brazil.
Life Sci. 2020 Sep 1;256:117920. doi: 10.1016/j.lfs.2020.117920. Epub 2020 Jun 6.
We investigated the effects of high-intensity interval and continuous short-term exercise on body composition and cardiac function after myocardial ischemia-reperfusion injury (IRI) in obese rats.
Rats fed with a standard chow diet (SC) or high-fat diet (HFD) for 20 weeks underwent systolic blood pressure (SBP), glycemia and dual-energy X-ray absorptiometry analyses. Then, animals fed with HFD were subdivided into three groups: sedentary (HFD-SED); moderate-intensity continuous training (HFD-MICT); and high-intensity interval training (HFD-HIIT). Exercised groups underwent four isocaloric aerobic exercise sessions, in which HFD-MICT maintained the intensity continuously and HFD-HIIT alternated it. After exercise sessions, all groups underwent global IRI and myocardial infarct size (IS) was determined histologically. Fat and muscle mass were weighted, and protein levels involved in muscle metabolism were assessed in skeletal muscle.
HFD-fed versus SC-fed rats reduced lean body mass by 31% (P < 0.001), while SBP, glycemia and body fat percentage were increased by 10% (P = 0.04), 30% (P = 0.006) and 54% (P < 0.001); respectively. HFD-induced muscle atrophy was restored in exercised groups, as only HFD-SED presented lower gastrocnemius (32%; P = 0.001) and quadriceps mass (62%; P < 0.001) than SC. PGC1-α expression was 2.7-fold higher in HFD-HIIT versus HFD-SED (P = 0.04), whereas HFD-HIIT and HFD-MICT exhibited 1.7-fold increase in p-mTOR levels compared to HFD-SED (P = 0.04). Although no difference was detected among groups for IS (P = 0.30), only HFD-HIIT preserved left-ventricle developed pressure after IRI (+0.7 mmHg; P = 0.9).
Short-term exercise, continuous or HIIT, restored HFD-induced muscle atrophy and increased mTOR expression, but only HIIT maintained myocardial contractility following IRI in obese animals.
本研究旨在探讨高强度间歇训练和短时间连续运动对肥胖大鼠心肌缺血再灌注损伤后体成分和心功能的影响。
20 周龄时，给予标准饲料（SC）或高脂饲料（HFD）喂养的大鼠进行收缩压（SBP）、血糖和双能 X 射线吸收法分析。然后，将 HFD 喂养的大鼠分为三组：安静组（HFD-SED）、中等强度连续训练组（HFD-MICT）和高强度间歇训练组（HFD-HIIT）。运动组进行了四节等热量的有氧运动，其中 HFD-MICT 持续保持强度，而 HFD-HIIT 则交替进行。运动后，所有组均进行整体缺血再灌注损伤，通过组织学方法确定心肌梗死面积（IS）。称重脂肪和肌肉质量，并评估骨骼肌中涉及肌肉代谢的蛋白水平。
与 SC 喂养的大鼠相比，HFD 喂养的大鼠的瘦体重减少了 31%（P<0.001），而 SBP、血糖和体脂百分比分别增加了 10%（P=0.04）、30%（P=0.006）和 54%（P<0.001）。运动组恢复了 HFD 诱导的肌肉萎缩，因为只有 HFD-SED 的比目鱼肌（32%；P=0.001）和股四头肌质量（62%；P<0.001）低于 SC。与 HFD-SED 相比，HFD-HIIT 中 PGC1-α 的表达增加了 2.7 倍（P=0.04），而 HFD-HIIT 和 HFD-MICT 中 p-mTOR 水平增加了 1.7 倍（P=0.04）。尽管各组的 IS 没有差异（P=0.30），但只有 HFD-HIIT 能在肥胖动物的缺血再灌注损伤后保持左心室发展压力（+0.7mmHg；P=0.9）。
短期运动，无论是连续运动还是 HIIT，都能恢复 HFD 诱导的肌肉萎缩并增加 mTOR 的表达，但只有 HIIT 能在肥胖动物的缺血再灌注损伤后保持心肌收缩力。
