Sarcopenia

The age-related loss of muscle mass, strength and function.

Sarcopenia is the progressive loss of muscle mass, strength and physical function that accompanies ageing when nothing is done about it. The European working group that sets the definition calls it a muscle disease rooted in changes that accumulate across a lifetime, and notes it can begin well before old age.

The definition changed in an instructive way in 2019. Low muscle strength became the primary criterion, with low muscle quantity used to confirm the diagnosis and poor physical performance marking severe cases. Strength, in other words, turned out to matter more than size, which reframes the whole problem: this is about what the muscle can do, not what it weighs.

It matters because muscle underpins metabolism, mobility, balance and the ability to get off the floor, and because losing it predicts falls, fractures, hospital stays and loss of independence. It is the difference between later decades spent living in your own home and later decades spent managing.

Grip strength is the everyday shorthand, and it earns its place: in half a million UK Biobank participants, every 5 kg of lower grip strength came with roughly 16 to 20% higher all cause mortality, alongside higher cardiovascular, respiratory and cancer risk. Grip is a proxy for whole body strength rather than a magic hand measurement, so the answer is not hand exercises.

Most of the decline is not inevitable. A great deal of what gets attributed to age is disuse, and the intervention with the best evidence is resistance training, which works into the ninth decade. The LIFTMOR trial put postmenopausal women with low bone mass through eight months of twice weekly heavy training and improved both bone density and physical function, without adverse events, in exactly the group traditionally told to be careful.

Protein is the supporting act. Older muscle responds less to a given dose, so the PROT-AGE recommendations start healthy older adults at 1.0 to 1.2 g per kg a day rather than the general reference intake, and pair it with resistance training rather than offering it as an alternative.

In practice, the prevention starts decades early: build muscle while it is easy, keep training when it is not, and treat difficulty rising from a chair or a weakening grip as a signal worth acting on rather than a joke about getting old.

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