Biodynamics and Human Performance Center, Georgia Southern University (Armstrong Campus), Savannah, GA 31419, USA.
Nutrients. 2021 Feb 23;13(2):706. doi: 10.3390/nu13020706.
Globally, people 65 years of age and older are the fastest growing segment of the population. Physiological manifestations of the aging process include undesirable changes in body composition, declines in cardiorespiratory fitness, and reductions in skeletal muscle size and function (i.e., sarcopenia) that are independently associated with mortality. Decrements in muscle protein synthetic responses to anabolic stimuli (i.e., anabolic resistance), such as protein feeding or physical activity, are highly characteristic of the aging skeletal muscle phenotype and play a fundamental role in the development of sarcopenia. A more definitive understanding of the mechanisms underlying this age-associated reduction in anabolic responsiveness will help to guide promyogenic and function promoting therapies. Recent studies have provided evidence in support of a bidirectional gut-muscle axis with implications for aging muscle health. This review will examine how age-related changes in gut microbiota composition may impact anabolic response to protein feeding through adverse changes in protein digestion and amino acid absorption, circulating amino acid availability, anabolic hormone production and responsiveness, and intramuscular anabolic signaling. We conclude by reviewing literature describing lifestyle habits suspected to contribute to age-related changes in the microbiome with the goal of identifying evidence-informed strategies to preserve microbial homeostasis, anabolic sensitivity, and skeletal muscle with advancing age.
全球范围内，65 岁及以上的人群是人口增长最快的年龄段。衰老过程的生理表现包括身体成分的不良变化、心肺功能下降，以及骨骼肌大小和功能的减少（即肌肉减少症），这些都与死亡率独立相关。肌肉对合成代谢刺激（如蛋白质摄入或体力活动）的蛋白质合成反应能力下降（即合成代谢抵抗），是衰老骨骼肌表型的高度特征，并在肌肉减少症的发展中起关键作用。更明确地了解导致这种与年龄相关的合成代谢反应能力下降的机制，将有助于指导促肌生成和促进功能的治疗。最近的研究为具有衰老肌肉健康意义的双向肠道-肌肉轴提供了证据。本综述将探讨肠道微生物组组成的年龄相关变化如何通过蛋白质消化和氨基酸吸收、循环氨基酸可用性、合成代谢激素产生和反应性以及肌肉内合成代谢信号的不利变化，影响蛋白质喂养的合成代谢反应。最后，我们通过回顾描述生活方式习惯的文献来进行总结，这些习惯被怀疑与微生物组的年龄相关变化有关，目的是确定有证据支持的策略，以保持微生物组内稳态、合成代谢敏感性和随着年龄增长的骨骼肌。
