What the study asked
The study asked whether strength or muscle mass was the better marker to watch in older adults, using the Health, Aging and Body Composition cohort.
What it found
In this cohort, quadriceps and grip strength were strongly associated with mortality, while measured muscle size was not strongly related to mortality. That is why the study is read as evidence about muscle performance and quality rather than muscle size.
What it does not show
It is an association, not proof that strength causes longer survival. It was not a broad jump study, and it did not test or validate any Systematic test or standard.
The evidence
Each cited source is labeled according to how it supports the particular claim on this page. Direct test evidence, underlying-capacity findings and population reference values are distinguished from Systematic-defined protocols and standards. Historical development notes are retained internally rather than presented as public evidence. A study of an underlying capacity is never presented as validation of the Systematic test itself.
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Underlying-capacity evidence
Newman et al. (2006). Strength, but not muscle mass, is associated with mortality in the health, aging and body composition study cohort. The journals of gerontology. Series A, Biological sciences and medical sciences.
What it found. In the Health, Aging and Body Composition cohort, quadriceps and grip strength were strongly associated with mortality, while measured muscle size was not strongly related to mortality.
What it does not show. It was not a broad-jump study and did not validate a Systematic test.
The Systematic Healthspan Assessment is a physical baseline. It is not a diagnosis, and it does not estimate a biological age, a disease risk or a lifespan.