Capturing what counts in muscle failure: a critical appraisal of the current operational models of sarcopenia.

Sarcopenia was originally conceptualised to describe a neuromuscular condition that could help to explain, at least partly, the effect of unsuccessful ageing on the ability of older adults (ie, those aged 60 years and older) to maintain independent mobility. Over time, international committees have standardised the definition and operationalisation of sarcopenia. However, a key issue in diagnosing sarcopenia remains as the current definitions are primarily based on expert opinion, with no clear explanation or description of the method used to prioritise the diagnostic criteria for sarcopenia, rather than on the integration of subjective methods (eg, expert opinion) with hierarchical evidence and advanced statistical methodologies. This issue has led to considerable variability in the reported prevalence rates of sarcopenia, inconsistent findings regarding sarcopenia as a predictor of adverse outcomes, and major challenges in the development of effective non-pharmacological (eg, physical exercise, nutrition), pharmacological therapies, or reliable biomarkers of disease status. The ambiguity on what is being measured under the present definitions of sarcopenia raises the fundamental question of whether these models truly represent the most accurate and clinically useful constructs of age-related muscle failure. In this Personal View, we critically examine the current state of sarcopenia research and highlight the need for a revised approach that integrates physiological face validity and clinical applicability.