Sarcopenia is more
than a muscle problem.

When someone becomes weaker with age, it is tempting to look first at the amount of muscle they have lost. Measure the muscle, build it back, and expect movement to improve.

Orssatto and colleagues ask us to reconsider that explanation. In their 2026 Personal View, Reframing sarcopenia as a disease of the ageing motor system, they argue that the condition’s biology extends across the system that produces and controls movement [1].

This article explains their argument in plain language. It is a summary and commentary on a conceptual paper, rather than a report of a new exercise trial.

What the paper is arguing

The authors distinguish the clinical syndrome—weakness and impaired physical performance—from the disease model used to explain it. Definitions have increasingly emphasised strength and performance, yet research and treatment have often remained focused on muscle tissue [1].

That mismatch matters. People with similar amounts of muscle can have different levels of strength and mobility. The paper also discusses interventions that increased muscle mass without consistently producing comparable functional benefits. An increase in tissue does not guarantee an equivalent improvement in what a person can do.

The authors are not dismissing muscle biology. Their argument is that muscle-focused explanations are incomplete when the outcome we want to understand is voluntary force or movement.

Why muscle quality does not finish the explanation

Looking beyond size to intrinsic muscle function is useful, but it still leaves part of the picture unexplained. Orssatto and colleagues argue that even measures of muscle’s contractile capacity cannot fully account for age-related losses in strength and mobility [1].

Walking illustrates the problem. It depends on muscle, but also on balance, sensory information, pain, cognition and cardiorespiratory fitness. A slow walking speed can be a valuable sign of increased risk while remaining a poor guide to exactly which component is limiting performance.

The paper gives particular attention to power: producing force at speed. Rising from a chair, climbing stairs and responding to a loss of balance involve more than the maximum force a muscle can generate. How quickly the nervous system activates muscle also matters. Even so, no single performance measure identifies every underlying mechanism.

From the brain to the muscle

Movement requires communication and coordination across several levels. The authors describe age-related changes in planning and descending neural commands, spinal motor-neuron function, peripheral nerves, neuromuscular transmission and muscle tissue. Sensory feedback also helps the system adjust force, position and balance [1].

The important point is interaction. Reduced neural drive may contribute to disuse and muscle loss; changes in muscle and sensory feedback may, in turn, affect motor control. The authors therefore propose a coupled model of neural and muscular ageing. They do not simply replace a muscle-only explanation with a nerve-only one.

They also set boundaries. This framework does not make every mobility problem sarcopenia, and it does not label all normal ageing as disease. A dominant neurological, joint or other pathology still needs its own diagnosis and management.

What would change in assessment?

The authors suggest two stages, with the whole motor system in view from the beginning [1].

First: practical clinical screening. Identify weakness and mobility limitations using feasible measures, while considering signs of both neural and muscular involvement. They discuss developing more informative measures of power, rapid force production, force steadiness and movement control. These are candidates for validation, not an established new diagnostic battery.

Second: detailed investigation when it could change a decision. Specialist or research assessment might use motor-unit analysis, nerve-conduction testing, measures of neuromuscular transmission, brain stimulation or imaging. The purpose would be to understand the limiting mechanisms and help match interventions to the individual.

The proposal is selective. It does not mean every older adult needs an expensive neurological work-up. The authors also acknowledge that advanced tests can be difficult to access or tolerate, particularly in frailty and multimorbidity.

What this means for training

The paper describes resistance training as valuable because it challenges muscle and the neural processes involved in producing and coordinating force. It also discusses activities involving sensory input, balance and motor learning as ways of engaging the wider system [1].

My coaching interpretation is to keep physical capability central. Depending on the person’s goals, that might mean tracking strength alongside getting up from a chair, stepping, carrying or another relevant task. Body-composition changes can provide context, but should not stand in for measuring the task itself.

This paper does not establish a particular heavy-lifting prescription, prove that one exercise reverses neural ageing, or show that a single programme suits everyone. It supports asking broader questions about function and the mechanisms behind it.

What still needs to be tested

The authors explicitly acknowledge that the added value of their proposed measures is not yet established. Do they improve screening beyond existing tests? Can they help select more effective treatments? Do they improve functional outcomes at an acceptable cost? These remain empirical questions [1].

That makes this paper a research and clinical agenda, rather than a finished solution. Its contribution is to align the explanation of sarcopenia more closely with the outcome that matters: a person’s ability to generate force and move effectively.