Dos Santos Gustavo Barbosa, de Oliveira André Gustavo, Ramos Luiz Alberto Ferreira, Gomes-Marcondes Maria Cristina Cintra, Areas Miguel Arcanjo
Department of Structural and Functional Biology, Institute of Biology, State University of Campinas (UNICAMP), 13083-862 Campinas, São Paulo, Brazil.
Sport Science Department, Faculty of Physical Education, Metropolitan College of Campinas (Metrocamp), 13035-270 Campinas, São Paulo, Brazil.
Exp Physiol. 2016 Jul 1;101(7):811-20. doi: 10.1113/EP085704. Epub 2016 Jun 14.
What is the central question of this study? Can long-term leucine supplementation prevent prolonged strenuous endurance exercise induced cardiac injury? What is the main finding and its importance? Prolonged endurance exercise does not seem to exceed cardiac energetic capacity, hence it does not represent an energy threat to this organ, at least in trained subjects. However, it may induce, in susceptible individuals, a state of cardiac electrical instability, which has been associated with ventricular arrhythmias and sudden cardiac death. This situation might be worsened when combined with leucine supplementation, which leads to increased blood pressure and cardiac injury. Leucine supplementation failed to prevent cardiac fatigue symptoms and may aggravate prolonged strenuous exercise-induced cardiovascular disturbances in trained rats. Observational studies have raised concerns that prolonged strenuous exercise training may be associated with increased risk of cardiac arrhythmia and even primary cardiac arrest or sudden death. It has been demonstrated that leucine can reduce prolonged exercise-induced muscle damage and accelerate the recovery process. The aim of this study was to investigate the effects of prolonged strenuous endurance exercise on cardiovascular parameters and biomarkers of cardiac injury in trained adult male rats and assess the use of leucine as an auxiliary substance to prevent the likely cardiac adverse effects caused by strenuous exercise. Twenty-four male Wistar rats were randomly allocated to receive a balanced control diet (18% protein) or a leucine-rich diet (15% protein plus 3% leucine) for 6 weeks. The rats were submitted to 1 h of exercise, 5 days per week for 6 weeks. Three days after the training period, the rats were submitted to swimming exercise until exhaustion, and cardiac parameters were assessed. Exercising until exhaustion significantly increased cardiac biomarker levels, cytokines and glycogen content inhibited protein synthesis signalling and led to cardiac electrical disturbances. When combined with exercise, leucine supplementation led to greater increases in the aforementioned parameters and also a significant increase in blood pressure and protein degradation signalling. We report, for the first time, that leucine supplementation not only fails to prevent cardiac fatigue symptoms, but may also aggravate prolonged strenuous exercise-induced cardiovascular disturbances in trained rats. Furthermore, we find that exercising until exhaustion can cause cardiac electrical disturbances and damage cardiac myocytes.
本研究的核心问题是什么？长期补充亮氨酸能否预防长时间剧烈耐力运动诱发的心脏损伤？主要发现及其重要性是什么？长时间耐力运动似乎并未超出心脏的能量容量，因此至少在训练有素的受试者中，它对该器官不构成能量威胁。然而，在易感个体中，它可能诱发心脏电不稳定状态，这与室性心律失常和心源性猝死有关。当与亮氨酸补充剂联合使用时，这种情况可能会恶化，亮氨酸补充剂会导致血压升高和心脏损伤。补充亮氨酸未能预防心脏疲劳症状，且可能加重训练有素的大鼠长时间剧烈运动诱发的心血管紊乱。观察性研究引发了人们的担忧，即长时间剧烈运动训练可能与心律失常风险增加、甚至原发性心脏骤停或猝死有关。已经证明亮氨酸可以减少长时间运动诱发的肌肉损伤并加速恢复过程。本研究的目的是调查长时间剧烈耐力运动对训练有素的成年雄性大鼠心血管参数和心脏损伤生物标志物的影响，并评估亮氨酸作为辅助物质预防剧烈运动可能引起的心脏不良反应的作用。将24只雄性Wistar大鼠随机分为两组，分别给予平衡对照饮食（18%蛋白质）或富含亮氨酸的饮食（15%蛋白质加3%亮氨酸），持续6周。大鼠每周5天进行1小时运动，共6周。训练期结束3天后，让大鼠进行游泳运动直至精疲力竭，并评估心脏参数。运动至精疲力竭显著增加了心脏生物标志物水平、细胞因子和糖原含量，抑制了蛋白质合成信号传导并导致心脏电紊乱。当与运动联合时，补充亮氨酸导致上述参数有更大幅度的增加，同时血压和蛋白质降解信号也显著增加。我们首次报告，补充亮氨酸不仅未能预防心脏疲劳症状，而且可能加重训练有素的大鼠长时间剧烈运动诱发的心血管紊乱。此外，我们发现运动至精疲力竭会导致心脏电紊乱并损伤心肌细胞。
