How does gait change with frailty?

Slowness is one of the five criteria in the Fried frailty phenotype, alongside weakness, exhaustion, low activity, and weight loss. Frailty is typically accompanied by slower walking, shorter steps, a wider base of support, longer double support time, and greater stride-to-stride variability. A usual-pace gait speed at or below 0.8 m/s is a widely used screening threshold.

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Slowness as a defining criterion

The Fried phenotype defines frailty by the presence of three or more of five components: unintentional weight loss, self-reported exhaustion, low physical activity, weakness measured by grip strength, and slowness measured by usual-pace gait speed. One or two components is described as pre-frail.

The original phenotype defines slowness by sex- and height-stratified quintiles of walking speed. Many studies and clinical pathways substitute a single practical cut-off instead, most commonly 0.8 m/s over a 4-meter walk.

How gait itself differs

  • Reduced walking speed, which is the component the phenotype scores directly.
  • Shorter step and stride length, often with reduced cadence.
  • Longer double support time — more of each cycle spent with both feet on the ground.
  • Wider step width, increasing the base of support.
  • Greater stride-to-stride variability, reflecting a less consistent pattern.

These changes overlap substantially with those seen in sarcopenia, which is unsurprising given that low grip strength and slow gait speed are characteristic of both.

How well gait speed screens for frailty

A systematic review of simple instruments for identifying frailty in community-dwelling older people reported that a gait speed at or below 0.8 m/s had a sensitivity of 0.99 and a negative predictive value of 0.99 against a phenotype reference standard, with a specificity of 0.64 and a positive predictive value of 0.26.

The practical reading is asymmetric. A gait speed above 0.8 m/s makes frailty very unlikely, which makes the measure useful for ruling out. A gait speed at or below 0.8 m/s identifies a group in which only around one in four met the reference standard, so it is a trigger for fuller assessment rather than a finding in itself.

The 0.8 m/s figure also appears in the revised European sarcopenia consensus as an indicator of low physical performance. The same number is used in two different frameworks for different purposes, which is a frequent source of confusion.

Measurement consistency matters more here

Because interpretation turns on a threshold, protocol differences translate directly into misclassification. Walk distance, whether acceleration is included in the timed segment, pace instruction, use of an assistive device, and manual timing error can all move a measurement across 0.8 m/s.

Sex-related differences in walking speed are also substantial in some populations, and a single cut-off applied to a whole cohort can classify a large fraction of it as slow.

Where CurveAssure fits

CurveAssure measures the walk from video with a fixed spatial reference and the same processing on every recording, which removes manual timing and rater variability from the measurement. Grip strength is available through CurveGrip for research use only.

Frailty and sarcopenia are not validated indications for CurveCapture, and CurveCapture does not screen for or detect any condition. It reports measurements for a provider to interpret.

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