Sarcopenia: why some definitions now start with strength, not muscle mass

Most people picture sarcopenia as "losing muscle with age". The 2010 European definition still required low muscle mass, together with either low strength or poor physical performance, before the word sarcopenia applied. Two later definitions changed what comes first. EWGSOP2, published in 2019, starts with low muscle strength. The SDOC position statements, drawn from pooled cohort analyses, use low grip strength and slow usual walking and leave DXA-measured lean mass out. The 2019 Asian update did not: muscle mass is still required there for a full diagnosis. This piece explains why the order changed, what is measured today and what the treatment evidence does and does not show.

What changed between 2010 and 2019

In 2010 the European Working Group on Sarcopenia in Older People (EWGSOP) defined sarcopenia as low muscle mass together with either low muscle strength or low physical performance. Low muscle mass was required for the diagnosis. The suggested case-finding sequence started with walking speed, then grip strength, and used muscle mass to confirm. (Cruz-Jentoft et al., Age Ageing 2010)

In 2019 the same group published a revised consensus, known as EWGSOP2. It turned the order around: low muscle strength is now the key characteristic, low muscle quantity or quality confirms the diagnosis, and poor physical performance marks severe sarcopenia. The group also described sarcopenia as a muscle disease, "muscle failure", that is common in older age but can begin earlier in life. (Cruz-Jentoft et al., Age Ageing 2019)

This matters because it changes who gets identified. Under the 2019 algorithm, a person with low grip strength already has "probable sarcopenia" before any scan is done.

Why strength moved to the front

The shift was driven by what predicts outcomes in follow-up studies, not by theory.

• Health ABC cohort. In 2,292 adults aged 70–79 followed for about five years, lower quadriceps and grip strength were strongly associated with higher mortality. Muscle size measured by CT or by DXA was not strongly associated with mortality, and adjusting for muscle size barely weakened the link between strength and mortality. This is an observational association, not proof that building strength changes survival. (Newman et al., J Gerontol A 2006)

• SDOC analyses. The Sarcopenia Definition and Outcomes Consortium pooled eight prospective cohorts of community-dwelling older adults (13,421 men and 4,828 women). Low grip strength and slow walking each predicted falls, mobility limitation, hip fracture and death. Lean mass measured by DXA was not consistently associated with these outcomes. (Cawthon et al., J Am Geriatr Soc 2020)

On that basis the SDOC panel proposed a definition built on two measures only: weakness (low grip strength) and slowness (low usual walking speed). DXA lean mass was left out because in their data it did not predict outcomes in community-dwelling older adults. (Bhasin et al., J Am Geriatr Soc 2020)

A likely reason is that the DXA measure those cohorts set aside, appendicular lean mass, is not pure muscle: in the arms and legs it includes water, skin and connective tissue as well as muscle, and it says nothing about how well the muscle works. Organs are part of a whole-body lean-mass reading, not of the appendicular one. Strength reflects both the amount of muscle and its function, including its nerve supply.

What is measured today

The main definitions do not agree on everything, and their cut-offs differ.

• EWGSOP2, Europe, 2019. Entry point: low strength. Grip cut-off: under 27 kg in men, under 16 kg in women. Muscle mass confirms the diagnosis.

• AWGS, Asia, 2019 update. Entry point: screening, then strength or performance. Grip cut-off: under 28 kg in men, under 18 kg in women. Muscle mass is required for a full diagnosis; "possible sarcopenia" can be named without it.

• SDOC, USA, 2020. Entry point: weakness and slowness. Grip cut-off: under 35.5 kg in men, under 20 kg in women. Muscle mass is not included.

The European group also uses a chair-stand test (more than 15 seconds for five rises) as an alternative sign of low strength, and walking speed of 0.8 m/s or less as a sign of severe sarcopenia. (Cruz-Jentoft et al., 2019) The Asian update uses a 6-metre walk slower than 1.0 m/s, or five chair stands taking 12 seconds or longer. Against the European thresholds, 1.0 m/s is a faster walking cut-off and 12 seconds is a shorter chair-stand time, so both flag poor performance sooner. Calf circumference or a short questionnaire is the suggested first step in both the community and the hospital algorithm. (Chen et al., J Am Med Dir Assoc 2020)

Because the cut-offs differ, the same person can meet one definition and not another. That is a limitation of the field, not a measurement error.

In 2024 the Global Leadership Initiative in Sarcopenia (GLIS) reached a Delphi consensus on a global conceptual definition. Its experts agreed that muscle mass, muscle strength and muscle-specific strength (strength relative to the amount of muscle) all belong to sarcopenia, and that impaired physical performance is an outcome of sarcopenia rather than a part of it. An operational definition with measurements and cut-offs has not yet been published. (Kirk et al., Age Ageing 2024) So muscle mass has not disappeared from the concept. What changed is that strength is no longer secondary to it.

Screening tools

The SARC-F is a five-item questionnaire covering strength, walking, rising from a chair, climbing stairs and falls. (Malmstrom and Morley, J Am Med Dir Assoc 2013) It is a screening step, not a diagnosis. The international ICFSR guidelines suggest rapid screening with gait speed or SARC-F. (Dent et al., J Nutr Health Aging 2018)

Grip strength itself is cheap to measure with a hand dynamometer. We have written separately about what grip strength predicts in clinical practice and about what counts as a meaningful change in walking speed. If the question is how much muscle and fat you carry, body composition is a separate measurement with its own limits.

What the treatment evidence shows

The ICFSR guidelines, graded with the GRADE approach, are the clearest summary for older adults:

• Resistance-based physical activity: strong recommendation as the treatment of sarcopenia.

• Protein supplementation or a protein-rich diet: conditional (weak) recommendation.

• Vitamin D supplementation: no recommendation for or against, because the evidence was insufficient.

• Anabolic hormones: no recommendation, for the same reason.

(Dent et al., 2018) The Asian update likewise names exercise and nutrition as the mainstays and notes that longer-term benefits still need research. (Chen et al., 2020)

No medicine is approved specifically to treat sarcopenia. It received its own diagnosis code in the US version of ICD-10 (M62.84) in 2016. The editorial that announced the code described it as a step toward recording sarcopenia as a disease; it did not show that recording or research had already become easier. (Anker et al., J Cachexia Sarcopenia Muscle 2016)

What these studies do not tell you

• They mostly studied people over 65, often over 70. How the cut-offs apply to people in their forties or fifties is not established.

• The link between low strength and mortality comes from observational cohorts. It shows who is at higher risk, not that raising grip strength by a given amount changes that risk.

• Cut-offs were derived in particular populations (European, Asian, mainly North American cohorts). A number just above or below a threshold is a prompt for a conversation, not a verdict.

• A low grip reading is not always sarcopenia. The European consensus names hand arthritis as a reason grip may not be measurable and asks clinicians to look for other causes of low strength.

What to do with the number

If a grip test, a chair-stand test or a walking test comes out low, that is a reason to discuss it with a doctor, who can check for other causes and decide whether further assessment such as a DXA or bioimpedance measurement is useful. The value of the modern definitions is that the first step is a simple functional test that you can repeat and track over time.

This material is for information only and does not replace a consultation with a doctor.

Sources

• Cruz-Jentoft AJ et al. Sarcopenia: European consensus on definition and diagnosis. Age Ageing. 2010. PMID 20392703

• Cruz-Jentoft AJ et al. Sarcopenia: revised European consensus on definition and diagnosis. Age Ageing. 2019. PMID 30312372

• Newman AB et al. Strength, but not muscle mass, is associated with mortality in the Health, Aging and Body Composition Study cohort. J Gerontol A Biol Sci Med Sci. 2006. PMID 16456196

• Cawthon PM et al. Putative cut-points in sarcopenia components and incident adverse health outcomes: an SDOC analysis. J Am Geriatr Soc. 2020. PMID 32633824

• Bhasin S et al. Sarcopenia definition: the position statements of the Sarcopenia Definition and Outcomes Consortium. J Am Geriatr Soc. 2020. PMID 32150289

• Chen LK et al. Asian Working Group for Sarcopenia: 2019 consensus update on sarcopenia diagnosis and treatment. J Am Med Dir Assoc. 2020. PMID 32033882

• Kirk B et al. The conceptual definition of sarcopenia: Delphi consensus from the Global Leadership Initiative in Sarcopenia (GLIS). Age Ageing. 2024. PMID 38520141

• Malmstrom TK, Morley JE. SARC-F: a simple questionnaire to rapidly diagnose sarcopenia. J Am Med Dir Assoc. 2013. PMID 23810110

• Dent E et al. International clinical practice guidelines for sarcopenia (ICFSR): screening, diagnosis and management. J Nutr Health Aging. 2018. PMID 30498820

• Anker SD et al. Welcome to the ICD-10 code for sarcopenia. J Cachexia Sarcopenia Muscle. 2016. PMID 27891296