Drugs that build muscle have often failed to make older people move better, and a group of researchers now says the reason may be that muscle was never the whole story.
The argument comes from a review in The Lancet Healthy Longevity (2026) by Orssatto, Arnold, Ferrucci, Narici and Clark. It is a review and proposal, not a trial or an experiment. It enrolled no participants and tested no treatment. It makes a case for how sarcopenia, the age-related loss of muscle strength and function, should be understood.
According to the abstract, sarcopenia is a major driver of disability, frailty and loss of independence. Official definitions have already moved away from low muscle mass. They now centre on low muscle strength and impaired physical performance. The authors say the underlying disease model has stayed focused on muscle.
That focus, they write, has produced important advances in muscle biology. It has also guided decades of research in which drugs that increase muscle mass gave inconsistent benefits for function. Muscle mass and the intrinsic quality of muscle explain an important but incomplete share of the age-related decline in strength and mobility.
The authors point to the rest of the system. Ageing, they say, disrupts the entire motor system: the brain's movement centres, the spinal circuitry, the peripheral nerves, the junctions where nerves meet muscle, and the muscle itself. The result is reduced neural drive, coordination and force generation. In plain terms, the muscle may be present, but the signal telling it what to do is weaker.
They propose calling sarcopenia a disease of the ageing motor system. Current strength and performance criteria capture the clinical picture, they write, but there is room to improve. They want diagnosis that assesses the whole system, sorts people by mechanism, and supports therapies aimed at both nerves and muscle. Without that shift, they argue, meaningful therapeutic progress will remain challenging.
The review's lead author, Lucas Orssatto of the University of Queensland, wrote a companion piece published by Medical Xpress. It goes further than the abstract on practical detail. In it, he suggests clinicians could watch how quickly someone rises from a chair, not only whether they can. Other checks include unsteadiness during sustained effort, hand dexterity, and whether walking changes when a conversation is added. He also says sedative and anticholinergic medicines can blunt motor drive, so medication review belongs alongside strength training. The abstract itself does not cover these points, so they should be read as the author's commentary. The same piece is frank about limits. Orssatto writes that nobody has yet shown these newer measures beat existing screening tests, on outcomes or on cost. He also notes that neuromuscular expertise is unevenly available in primary care.
Trials that measure nerve function as well as muscle, and whether international working groups revise the diagnostic criteria for sarcopenia. Readers should not start or stop any exercise, medicine or treatment without talking to their own clinician.
Sources: The lancet. Healthy longevity (2026), Medical Xpress / The Lancet Healthy Longevity
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