A gait analysis is a structured look at how an athlete runs, undertaken to answer a specific question. That last clause is what separates a useful analysis from an expensive video. "Why does my left calf keep failing", "why do I lose form after ninety minutes" and "am I overstriding" are answerable questions. "Analyse my running" is not, and tends to produce a report listing every deviation from an imaginary ideal, most of which should be left alone.
The protocol
A conventional assessment runs in a fixed sequence, and the sequence matters because each step conditions the next.
- Orientation and history. Training volume, injury record, footwear history, and the specific complaint or question. Most findings are only interpretable against this.
- Pre-evaluation filming. The athlete's habitual gait recorded before any instruction, at more than one speed — typically an easy pace and something near threshold, because faults often appear only at one of them.
- Biomechanical assessment. Static and functional screening off the treadmill: ankle range, hip extension and abduction strength, single-leg stability. This is where a technique fault is separated from a strength deficit.
- Technique work and drills. One or two targeted changes introduced and rehearsed, not a list.
- Post-evaluation filming. The same views again, to confirm that the change is actually happening and has not created something worse.
- Graded test. Where a physiological reference is wanted, a stepped test with heart rate, effort and where available blood lactate.
- Follow-up at about twelve weeks. The full protocol repeated for comparison.
Filming, and the views that matter
Three viewpoints cover almost everything. From the side: foot position at contact relative to the body, knee flexion at loading, trunk lean, vertical oscillation, and hip extension at toe-off. From the front: knee tracking, foot crossover toward the midline, arm carriage. From behind: pelvic drop, heel whip, and rear-foot motion.
A high frame rate matters more than image quality. Contact lasts roughly two tenths of a second, so a standard rate gives only a handful of frames within it and will miss the loading peak entirely. The general practicalities of filming are covered in video as a coaching instrument.
What is measured
- Step rate — the most repeatable number in the assessment and the one most changes are made through.
- Foot position at contact — the horizontal distance between the foot and the centre of mass, which is the meaningful version of "overstriding".
- Vertical oscillation — displacement of the centre of mass per stride.
- Contact time and its symmetry — a consistent left-right difference is worth investigating, particularly after an injury.
- Pelvic drop and knee valgus — frontal-plane control, usually a strength finding rather than a technique one.
- Trunk lean — distinguishing a whole-body lean from the ankles from a flexion at the waist.
Cues, and which ones work
Once a target is chosen, the change is delivered as a cue — a short instruction the athlete can hold while running. Cues are not interchangeable, and their effects differ substantially. Work on the relative importance of three gait retraining cues compares common instructions for reducing vertical ground reaction force and finds they are not equally effective, which is a useful caution against assuming any plausible-sounding cue will do.
Two general principles hold. Cues that direct attention outside the body — running softly, landing quietly, running as if over thin ice — usually work better than cues directing attention to a body part. And one cue at a time is the limit; two instructions produce an athlete concentrating on neither.
Foot strike: change it carefully or not at all
Deliberately altering foot strike is the most commonly requested and most commonly regretted change in gait retraining. It does alter loading — but it moves load rather than removing it. Study of biomechanical effects following footstrike pattern modification documents this redistribution directly: moving from a rearfoot to a forefoot pattern reduces loading at the knee and increases it at the ankle and Achilles.
For an athlete with a knee problem and a robust calf that may be an excellent trade. For an athlete with a history of Achilles trouble it is the wrong direction. Either way, the receiving tissue has not been conditioned for the new load, so the change requires a deliberate reduction in volume while it beds in.
In most cases the better first move is not to change foot strike at all but to raise cadence slightly, which brings the landing closer to the body and often changes the strike pattern as a by-product, without asking the athlete to think about their feet.
Strength findings versus technique findings
The most valuable output of a good assessment is often not a technique correction but the recognition that a visible fault is a strength problem. Pelvic drop, inward knee collapse and a trunk that rotates to compensate are all patterns an athlete cannot simply be instructed out of, because the instruction asks them to hold a position they do not yet have the capacity to hold.
These findings route to strength work rather than to drills, and they resolve on a timescale of months rather than sessions. An assessment that issues a cue for every one of them will produce an athlete concentrating hard on running badly.
Why the follow-up is twelve weeks
A running pattern is a deeply grooved motor habit. Retested after two weeks, an athlete demonstrates that they remember the instruction; retested after twelve, they demonstrate whether the pattern has changed. Twelve weeks is also long enough for the conditioning response in whatever tissue received the redistributed load, which is the question that actually determines whether the change was a good idea.
The follow-up must repeat the original protocol exactly — the same speeds, the same camera positions, the same measurements — or the comparison means nothing. Between assessments the work is ordinary running, with the change rehearsed on short easy sessions before it is asked for under fatigue, as described in running technique and biomechanics.