gait speed

Of all the simple measurements in rehabilitation, one keeps surprising people with how much it reveals: how fast a person walks. Gait speed is just distance divided by time — usually how many metres a person covers per second over a short, measured walk. It sounds almost too plain to matter, yet it has been called a 'sixth vital sign' because it summarizes so much about a person's health and function in one easy number.

To measure it, the person walks a marked distance — commonly four metres, sometimes ten — at their comfortable pace, and the time is recorded with a stopwatch, giving a speed in metres per second. Walking turns out to be a demanding, whole-body act: it needs leg strength, balance, joint motion, healthy nerves, a working heart and lungs, vision, and even attention. When any of these falters, the body's quiet response is usually to slow down. So a single speed reflects the integrated state of all those systems at once. Researchers have linked slower comfortable gait speeds with greater risk of falls, hospitalization, loss of independence, and shorter survival in older adults, while faster speeds track with better outcomes.

Gait speed matters because it is cheap, quick, reliable, and meaningful all at once, and because it is sensitive enough to track recovery — a person who speeds up after surgery or therapy is genuinely improving, and crossing certain thresholds can mark milestones like being able to cross a street within the timing of a traffic light. The honest caveats are that comfortable speed and maximum speed answer different questions, the measured distance and whether a flying start is used affect the number, and like any single measure it shows the 'how much' but not the 'why', so it complements rather than replaces a full assessment.