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Glossary

Sarcopenia

Defined in topic 35

The age-related loss of muscle mass and strength, now screened for with grip strength or gait speed: what a muscle can do predicts falls and death better than its bulk.

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Where this comes from

In the reference topic that owns this term

Reference topic 35, The Hallmarks of Aging, states the mismatch as a card: what the system evolved to expect, what it gets instead, and what happens in the gap.

Mismatch card

What it expects

Muscles loaded most days, food that comes and goes, microbes, and stressors that end.

What it gets

Decades of low mechanical load, continuous food, and stress without resolution.

What happens in the gap

Strength falls away faster than age alone requires, while the processes that age cells run with fewer of the brakes the body evolved to apply.

The full card, and the topic behind it

What that chapter recommends

3 of the 5 graded recommendations in Reference topic 35, strongest evidence first. How the grades work.

  1. Build and keep strength

    ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.

    Strength predicted lower all-cause and cancer mortality in 8,762 men independently of aerobic fitness, and grip strength stratifies risk across a large multinational cohort.

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  2. Measure strength, not your "biological age"

    ProbableEvidence grade: Probable. Good observational evidence with a plausible mechanism, or small or few trials.

    A hand dynamometer or a rise from the floor (Chapter 6) gives you a number tied to outcomes in cohort studies and to the clinical screening criteria for sarcopenia.

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  3. Calorie restriction as an anti-aging strategy

    EmergingEvidence grade: Emerging. Early, small, animal-only, or actively contested.

    Two years of attempted 25% restriction, achieved at about 12%, slowed one methylation clock by 2 to 3% and moved two others not at all. That is a real finding and not a demonstration of a longer or healthier life.

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Related terms

The argument behind this term, its studies and its notes are in Reference topic 35 of the reference library. The book gives the practical version. Get the book.