Shortening your stride is the cheapest injury insurance there is

Raising cadence a few per cent lowers the load on every landing, and it costs a distance runner almost nothing in speed.

A runner covering ground at a given speed has exactly two ways to do it: fewer, longer steps or more, shorter ones. The speed comes out the same. The forces do not, and that asymmetry is one of the few genuinely free improvements available to anybody who runs a lot.

Here is the mechanism, and it is mostly geometry. A long stride puts the foot down further ahead of the hips. The leg meets the ground with the knee straighter and the shin angled backwards, which means the landing acts partly as a brake, and the impact travels up a limb that is poorly arranged to absorb it. Shorten the stride and raise the turnover to compensate, and the foot lands closer to underneath the body, the knee is more bent, and a much larger share of the impact goes into muscle and tendon that are built to store it rather than into bone and joint that are not.

The usual objection is that shorter steps must be less efficient. In a trained runner, over a modest change of five to ten per cent, the metabolic difference is small enough to disappear inside daily variation, and everybody has a preferred cadence their body will drift back to anyway. The change worth making is not dramatic. It is a nudge, held for a few weeks until it stops requiring attention.

Where I would be careful is with sprinting, because the logic reverses. At maximum speed the limiting factor is how much force you can put into the ground in a very short contact, and deliberately shortening the stride there costs you the thing you were trying to produce. This is an endurance running argument, not a universal one, and I see it applied wrongly in both directions by people who read one summary.

The other honest caveat is that cadence is a proxy. What you want is the foot landing under the hips, and you can achieve that at almost any turnover by leaning from the ankles and not reaching. Cadence is just the easiest handle, because every watch counts it and nobody needs a laboratory.

Most recreational runners are reaching. Watch a park on a Sunday morning and count the straight front legs.

It is the single most common thing wrong, and the fix is free.