Movement · 4 min read
Range of motion norms are a standard reference point in movement assessment. A hip should flex to this angle. A shoulder should reach that degree. These values are widely used — but what they actually tell you about an individual athlete is considerably less than the way they are applied suggests.
By DVOTION Team ·
Most range of motion reference values come from population studies — measurements taken across large groups of people to produce average ranges. The American Academy of Orthopaedic Surgeons norms are among the most widely used in clinical and performance settings.
These values are useful for identifying gross deficits — a shoulder that cannot lift past 90 degrees is clearly restricted by any standard. But outside of flagging major limitations, the comparison between an individual's range and a population average is a weaker tool for understanding what that individual's system is actually doing than it appears.
A population norm is a between-subject finding: it describes variation across many different people. Using it to assess a single individual is between-subject reasoning — comparing this person to others.
The more meaningful question is within-subject: how does this person's range on one side compare to the other? How does their range under load compare to unloaded? How does range change when the organisation of the system above or below the joint is altered?
Within-subject comparison reveals asymmetry, context-dependence and system behaviour — information about how this specific system is organised. Between-subject comparison reveals only whether the person is above or below an average. For performance purposes, the within-subject picture is almost always more actionable.
The range an athlete can access in any given test is not a fixed property of that joint. It is an output of the system at that moment — reflecting the position of the centre of gravity, the pressure management strategy currently in use, the tension in adjacent segments, and what the system currently allows access to.
This is why an athlete can show significant hip range on a passive test but very limited range in a loaded movement. Or why range improves immediately when the organisation of the system above or below the joint is changed. The joint has not suddenly become more mobile — the system changed what it was permitting.
Range of motion is a readout of strategy, not a fixed property of tissue.
When an athlete shows limited range — whether below a norm or below their own previous baseline — the useful question is not 'how do we increase that range?' It is 'what is the system currently organising around that produces this range?'
A hip that stops early in flexion is reflecting a strategy. Perhaps the system cannot yield inward under load and is protecting against further pressure accumulation. Perhaps the base of support cannot accommodate the range without instability. Perhaps a constraint further up the chain is pulling the available range down.
Chasing range directly — stretching into restriction, forcing a joint through end range repeatedly — addresses the output without the cause. It may temporarily increase range while the system is in a passive, unloaded state. It rarely changes what the system accesses under the conditions that actually matter for training and performance.
An assessment that only asks 'does this meet the norm?' is answering the wrong question. The more useful assessment asks: what does this range tell me about how the system is currently organised, and what does the system need in order to access more?
When range is understood as a system output rather than a tissue property, it becomes information — about strategy, about constraint, about what the system can and cannot access right now, and why. That information is actionable in a way that a number compared to a population average rarely is.
This is the distinction between screening for deficits and understanding what the system is actually doing. Both have their place. Only one of them tells you what to do next.
Not necessarily. Within-normal range does not mean the system is organising efficiently. An athlete can have full range available but access it through a compensatory strategy — which shows up in how they move under load rather than in a passive range test.
Yes — and it frequently does. When the movement strategy changes and the system finds better organisation, range often improves without any direct flexibility work. The restriction was a system output, and a different strategy produces a different output.
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