Department of Biomedical Sciences, CIR-MYO Myology Center, Neuromuscular Physiology Laboratory, University of Padova, Padua, Italy.
Department of Biomedical Sciences, Neuromuscular Physiology Laboratory, University of Padova, Padua, Italy.
Eur J Sport Sci. 2021 Apr;21(4):614-635. doi: 10.1080/17461391.2020.1761076. Epub 2020 May 12.
The COVID-19 pandemic is an unprecedented health crisis as entire populations have been asked to self-isolate and live in home-confinement for several weeks to months, which in itself represents a physiological challenge with significant health risks. This paper describes the impact of sedentarism on the human body at the level of the muscular, cardiovascular, metabolic, endocrine and nervous systems and is based on evidence from several models of inactivity, including bed rest, unilateral limb suspension, and step-reduction. Data form these studies show that muscle wasting occurs rapidly, being detectable within two days of inactivity. This loss of muscle mass is associated with fibre denervation, neuromuscular junction damage and upregulation of protein breakdown, but is mostly explained by the suppression of muscle protein synthesis. Inactivity also affects glucose homeostasis as just few days of step reduction or bed rest, reduce insulin sensitivity, principally in muscle. Additionally, aerobic capacity is impaired at all levels of the O cascade, from the cardiovascular system, including peripheral circulation, to skeletal muscle oxidative function. Positive energy balance during physical inactivity is associated with fat deposition, associated with systemic inflammation and activation of antioxidant defences, exacerbating muscle loss. Importantly, these deleterious effects of inactivity can be diminished by routine exercise practice, but the exercise dose-response relationship is currently unknown. Nevertheless, low to medium-intensity high volume resistive exercise, easily implementable in home-settings, will have positive effects, particularly if combined with a 15-25% reduction in daily energy intake. This combined regimen seems ideal for preserving neuromuscular, metabolic and cardiovascular health.
新型冠状病毒肺炎大流行是一场前所未有的卫生危机，整个社会群体都被要求进行自我隔离，并在家中被禁闭数周乃至数月，这本身就是一个具有重大健康风险的生理挑战。本文描述了久坐不动对肌肉、心血管、代谢、内分泌和神经系统等人体层面的影响，其依据的是多种不活动模型的证据，包括卧床休息、单侧肢体悬吊和减少步数。这些研究的数据表明，肌肉萎缩迅速发生，在不活动两天内即可检测到。这种肌肉质量的损失与纤维去神经支配、运动终板损伤和蛋白质分解增加有关，但主要是由于肌肉蛋白合成受到抑制。不活动还会影响葡萄糖稳态，因为仅仅几天的步数减少或卧床休息，就会降低肌肉的胰岛素敏感性。此外，在心血管系统，包括外周循环，到骨骼肌氧化功能的 O 级联的各个层面，有氧能力都受到损害。在身体不活动期间，能量处于正平衡会导致脂肪沉积，与全身炎症和抗氧化防御的激活有关，从而加剧肌肉损失。重要的是，常规运动练习可以减轻不活动的这些有害影响，但目前尚不清楚运动的剂量-反应关系。尽管如此，低到中等强度、大运动量的抗阻运动，很容易在家中实施，将产生积极影响，尤其是如果与每天能量摄入减少 15-25%相结合。这种综合方案似乎是维持神经肌肉、代谢和心血管健康的理想选择。
