The influence of physical activity on sarcopenia
Authors: Charlotte Beaudart
Journal: The Lancet Healthy Longevity (2024)

Sarcopenia, which is characterised by the progressive loss of muscle mass, strength, and function associated with ageing,1Cruz-Jentoft AJ Bahat G Bauer J et al.Sarcopenia: revised European consensus on definition and diagnosis.Age Ageing. 2019; 48: 16-31Crossref PubMed Scopus (5996) Google Scholar can lead to adverse outcomes, including impaired physical performance, increased risk of falls, and decreased quality of life.2Beaudart C Demonceau C Reginster J et al.Sarcopenia and health-related quality of life: a systematic review and meta-analysis.J Cachexia Sarcopenia Muscle. 2023; 14: 1228-1243Crossref Scopus (5) Google Scholar, 3Veronese N Demurtas J Soysal P et al.Sarcopenia and health-related outcomes: an umbrella review of observational studies.Eur Geriatr Med. 2019; 10: 853-862Crossref Scopus (48) Google Scholar, 4Beaudart C Zaaria M Pasleau F Reginster J-Y Bruyère O Stenroth L Health outcomes of sarcopenia: a systematic review and meta-analysis.PLoS One. 2017; 12e0169548 Crossref PubMed Scopus (657) Google Scholar As a prevalent concern in the ageing population,5Petermann-Rocha F Balntzi V Gray SR et al.Global prevalence of sarcopenia and severe sarcopenia: a systematic review and meta-analysis.J Cachexia Sarcopenia Muscle. 2022; 13: 86-99Crossref PubMed Scopus (258) Google Scholar understanding the factors that might influence its development, such as the role of physical activity, is crucial for effective preventive measures and interventions. Juan Luis Sánchez-Sánchez and colleagues’ systematic review and meta-analysis6Sánchez-Sánchez JL He L Morales JS et al.Association of physical behaviours with sarcopenia in older adults: a systematic review and meta-analysis of observational studies.Lancet Healthy Longev. 2024; 5: e108-e119Google Scholar summarises the results of 124 observational epidemiological studies to derive an understanding of the role of physical activity and sedentary behaviours in prevention or development of sarcopenia. Although only a subset of these studies was included in the meta-analysis and exploited in quantitative statistics, this Article stands as the most up-to-date and comprehensive evidence for the association between physical activity and sarcopenia. In their Bayesian meta-analysis, Sánchez-Sánchez and colleagues reported that higher levels of physical activity are associated with a reduced risk of sarcopenia.6Sánchez-Sánchez JL He L Morales JS et al.Association of physical behaviours with sarcopenia in older adults: a systematic review and meta-analysis of observational studies.Lancet Healthy Longev. 2024; 5: e108-e119Google Scholar Evidence from cross sectional studies (n=21) resulted in a pooled OR of 0·49 (95% credible interval 0·37–0·62) and evidence from longitudinal studies (n=4) resulted in a pooled OR of 0·51 (0·27–0·94). These findings emphasise the importance of engaging older people in moderate-to-vigorous physical activity to mitigate the risk of sarcopenia. The pivotal role of health professionals is evident, because the intensity of physical activity might be a limiting factor to optimal engagement and adherence among older individuals. Patient-centred approaches are particularly crucial in this context and patient-preference studies investigating ways of proposing moderate-to-vigorous physical activity aligned with patient's preferences are greatly needed. However, despite proposing an exhaustive body of evidence in this area, it is essential to note that the strength of evidence appears to be low. This low strength is mainly due to the cross-sectional design of the included studies, inconsistencies between studies, and the low precision of estimates. Systematic reviews and meta-analyses have become exceedingly popular in all areas of medical research. Since systematic reviews and meta-analyses often inform evidence-based decision making in policy and clinical practice, these endeavours should adhere to a multitude of methodological standards to be trustworthy and unbiased. Unfortunately, many researchers undertake the task of crafting these synthesis articles without a thorough grasp of best research practices. Therefore, I wish to stress the importance of three aspects that deserve consideration. First and foremost, close collaboration with an experienced librarian to construct the search strategy is indispensable. As the essence of a systematic review is to be truly systematic, the search strategy should be meticulously crafted to capture the entirety of existing literature. To achieve this goal, a combination of controlled vocabulary (eg, MeSH terms on Medline [via PubMed]) and free-text keywords is mandatory. Sánchez-Sánchez and colleagues justified their partial adherence to this quality standard by citing the absence of appropriate descriptors for some key terms, such as muscle mass or muscle function.6Sánchez-Sánchez JL He L Morales JS et al.Association of physical behaviours with sarcopenia in older adults: a systematic review and meta-analysis of observational studies.Lancet Healthy Longev. 2024; 5: e108-e119Google Scholar Considering that descriptors such as sarcopenia could have been used, I do not fully agree with the justification. Therefore, it is important to acknowledge that the search strategy could have been of higher quality and is a limitation of the work. I urge all researchers to acknowledge the importance of building a team with appropriate skills and experience to create a high-quality search strategy (eg, a librarian) and not to underestimate the importance of this laborious yet indispensable early design step, because search strategies usually cannot be revised at later stages. Second, it is essential to be fully familiar with methodological standards for conducting systematic reviews and meta-analyses, such as PRISMA 2020 and AMSTAR2 criteria.7Page MJ McKenzie JE Bossuyt PM et al.The PRISMA 2020 statement: an updated guideline for reporting systematic reviews.BMJ. 2021; 372: n71Crossref PubMed Scopus (23861) Google Scholar, 8Shea BJ Reeves BC Wells G et al.AMSTAR 2: a critical appraisal tool for systematic reviews that include randomised or non-randomised studies of healthcare interventions, or both.BMJ. 2017; 358j4008 Google Scholar Authors often claim adherence to these standards without completing them accurately. Researchers should be aware that the non-completion of some items of these standards, such as not registering a protocol before conducting the review or not providing a list of excluded studies at the full-text selection stage with specific reasons for their exclusion, constitutes a severe flaw, immediately categorising the synthesis as low quality. Sánchez-Sánchez and colleagues’ work6Sánchez-Sánchez JL He L Morales JS et al.Association of physical behaviours with sarcopenia in older adults: a systematic review and meta-analysis of observational studies.Lancet Healthy Longev. 2024; 5: e108-e119Google Scholar is classified as high quality according to AMSTAR2 criteria,8Shea BJ Reeves BC Wells G et al.AMSTAR 2: a critical appraisal tool for systematic reviews that include randomised or non-randomised studies of healthcare interventions, or both.BMJ. 2017; 358j4008 Google Scholar with no critical weaknesses. I strongly believe that these standards should be applied to all submitted work, and that only meta-synthesis work of moderate-to-high quality should be published. My third point emphasises the statistical aspect of meta-analyses. One of the most common statistical errors reported in meta-analyses concerns the choice of the statistical model. The decision between using a random-effects model or a fixed-effects model should not be determined by the outcome of the test for heterogeneity. Instead, the decision should align with the researchers’ initial hypotheses and be stated in the protocol.9Cochrane TrainingCochrane handbook for systematic reviews of interventions.https://training.cochrane.org/handbookDate accessed: December 13, 2022Google Scholar In their protocol (CRD42022315865), Sánchez-Sánchez and colleagues stated that they would apply a random-effects model. Despite the absence of justification for this choice, they nevertheless closely adhered to their initial plan as outlined in the Article,6Sánchez-Sánchez JL He L Morales JS et al.Association of physical behaviours with sarcopenia in older adults: a systematic review and meta-analysis of observational studies.Lancet Healthy Longev. 2024; 5: e108-e119Google Scholar which is a gauge of transparency and quality. Upholding rigorous statistical practices not only enhances the validity of meta-analyses but also enhances the overall credibility and reliability of the findings. I declare no competing interests. Association of physical behaviours with sarcopenia in older adults: a systematic review and meta-analysis of observational studiesTotal and moderate-to-vigorous physical activity are inversely associated with sarcopenia. These findings might support the importance of moderate-to-vigorous, rather than light, intensity physical activity-based interventions to prevent sarcopenia. 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