The world population is ageing rapidly. As society ages, the incidence of physical limitations is dramatically increasing, which reduces the quality of life and increases healthcare expenditures. In western society, ~30% of the population over 55 years is confronted with moderate or severe physical limitations. These physical limitations increase the risk of falls, institutionalization, co-morbidity, and premature death. An important cause of physical limitations is the age-related loss of skeletal muscle mass, also referred to as sarcopenia. Emerging evidence, however, clearly shows that the decline in skeletal muscle mass is not the sole contributor to the decline in physical performance. For instance, the loss of muscle strength is also a strong contributor to reduced physical performance in the elderly. In addition, there is ample data to suggest that motor coordination, excitation-contraction coupling, skeletal integrity, and other factors related to the nervous, muscular, and skeletal systems are critically important for physical performance in the elderly. To better understand the loss of skeletal muscle performance with ageing, we aim to provide a broad overview on the underlying mechanisms associated with elderly skeletal muscle performance. We start with a system level discussion and continue with a discussion on the influence of lifestyle, biological, and psychosocial factors on elderly skeletal muscle performance. Developing a broad understanding of the many factors affecting elderly skeletal muscle performance has major implications for scientists, clinicians, and health professionals who are developing therapeutic interventions aiming to enhance muscle function and/or prevent mobility and physical limitations and, as such, support healthy ageing.
Purpose: Measurement of muscle mass is paramount in the screening and diagnosis of sarcopenia. Besides muscle quantity however, also quality assessment is important. Ultrasonography (US) has the advantage over dual-energy X-ray absorptiometry (DEXA) and bio-impedance analysis (BIA) to give both quantitative and qualitative information on muscle. However, before its use in clinical practice, several methodological aspects still need to be addressed. Both standardization in measurement techniques and the availability of reference values are currently lacking. This review aims to provide an evidence-based standardization of assessing appendicular muscle with the use of US. Methods: A systematic review was performed for ultrasonography to assess muscle in older people. Pubmed, SCOPUS and Web of Sciences were searched. All articles regarding the use of US in assessing appendicular muscle were used. Description of US-specific parameters and localization of the measurement were retrieved. Results: Through this process, five items of muscle assessment were identified in the evaluated articles: thickness, cross-sectional area, echogenicity, fascicle length and pennation angle. Different techniques for measurement and location of measurement used were noted, as also the different muscles in which this was evaluated. Then, a translation for a clinical setting in a standardized way was proposed. Conclusions: The results of this review provide thus an evidence base for an ultrasound protocol in the assessment of skeletal muscle. This standardization of measurements is the first step in creating conditions to further test the applicability of US for use on a large scale as a routine assessment and follow-up tool for appendicular muscle.
PURPOSE: In 2018, the SARCUS working group published a first article on the standardization of the use of ultrasound to assess muscle. Recommendations were made for patient positioning, system settings and components to be measured. Also, shortcomings in knowledge were mentioned. An important issue that still required standardization was the definition of anatomical landmarks for many muscles.METHODS: A systematic search was performed in Medline, SCOPUS and Web of Sciences looking for all articles describing the use of ultrasound in the assessment of muscle not described in the first recommendations, published from 01/01/2018 until 31/01/2020. All relevant terms used for older people, ultrasound and muscles were used.RESULTS: For 39 muscles, different approaches for ultrasound assessment were found that likely impact the values measured. Standardized anatomical landmarks and measuring points were proposed for all muscles/muscle groups. Besides the five already known muscle parameters (muscle thickness, cross-section area, pennation angle, fascicle length and echo-intensity), four new parameters are discussed (muscle volume, stiffness, contraction potential and microcirculation). The former SARCUS article recommendations are updated with this new information that includes new muscle groups.CONCLUSIONS: The emerging field of ultrasound assessment of muscle mass only highlights the need for a standardization of measurement technique. In this article, guidelines are updated and broadened to provide standardization instructions for a large number of muscles.
