The age-related loss of skeletal muscle mass and function: measurement and physiology of muscle fibre atrophy and muscle fibre loss in humans

Wilkinson, Daniel J.; Piasecki, M.; Atherton, Philip J.

Abstract

Age-related loss of skeletal muscle mass and function, sarcopenia, is associated with physical frailty and increased risk of morbidity (chronic diseases), in addition to all-cause mortality. The loss of muscle mass occurs incipiently from middle-age (~1%/year), and in severe instances can lead to a loss of ~50% by the 8-9th decade of life. This review will focus on muscle deterioration with ageing and highlight the two underpinning mechanisms regulating declines in muscle mass and function: muscle fibre atrophy and muscle fibre loss (hypoplasia) – and their measurement. The mechanisms of muscle fibre atrophy in humans relate to imbalances in muscle protein synthesis (MPS) and breakdown (MPB); however, since there is limited evidence for basal alterations in muscle protein turnover, it would appear that “anabolic resistance’ to fundamental environmental cues regulating diurnal muscle homeostasis (namely physical activity and nutrition), underlie age-related catabolic perturbations in muscle proteostasis. While the ‘upstream’ drivers of the desensitization of aged muscle to anabolic stimuli are poorly defined, they most likely relate to impaired efficiency of the conversion of nutritional/exercise stimuli into signalling impacting mRNA translation and proteolysis. Additionally, loss of muscle fibres has been shown in cadaveric studies using anatomical fibre counts, and from iEMG studies demonstrating motor unit loss, albeit with few molecular investigations of this in humans. We suggest that defining countermeasures against sarcopenia requires improved understandings of the co-ordinated regulation of muscle fibre atrophy and fibre loss, which are likely to be inextricably linked.

Citation

Wilkinson, D. J., Piasecki, M., & Atherton, P. J. (2018). The age-related loss of skeletal muscle mass and function: measurement and physiology of muscle fibre atrophy and muscle fibre loss in humans. Ageing Research Reviews, 47, 123-132. https://doi.org/10.1016/j.arr.2018.07.005

• Journal Article Type: Article
• Acceptance Date: Jul 18, 2018
• Online Publication Date: Jul 23, 2018
• Publication Date: Nov 30, 2018
• Deposit Date: Jul 24, 2018
• Publicly Available Date: Aug 9, 2018
• Journal: Ageing Research Reviews
• Print ISSN: 1568-1637
• Electronic ISSN: 1872-9649
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 47
• Pages: 123-132
• DOI: https://doi.org/10.1016/j.arr.2018.07.005
• Keywords: Muscle; Atrophy; Hypoplasia; Anabolic resistance; Denervation; Sarcopenia
• Public URL: https://nottingham-repository.worktribe.com/output/947580
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S156816371830134X
• Contract Date: Aug 9, 2018