Players get hurt slowing down, not speeding up

Tracking systems count sprints beautifully and count the thing that actually tears a muscle badly or not at all.

Braking is the part nobody counts properly.

Every squad now wears a unit between the shoulder blades and most of them carry limb-level sensors as well. The reports that come out the other end are full of top speeds, sprint counts, high-intensity distance, and a total load figure that gets emailed to a coach who has thirty seconds to look at it. All of that is real. It is also weighted towards acceleration, because acceleration is easy to define and easy to sell in a graph that goes up.

Deceleration is harder. The forces involved are larger, they last longer per stride, and they land on tissue in a lengthened position rather than a shortened one. A hamstring does not usually fail while it is pulling the leg through. It fails while it is trying to stop the shin from continuing, which is the same eccentric moment you find in the last stride before a change of direction and in the awkward stretch of an overrun ball.

So a midfielder who covers twelve kilometres in straight lines and a midfielder who covers ten with sixty hard stops are two different animals wearing the same summary. The second one is closer to injury. The report will suggest the first one worked harder.

There is a second blind spot, which is surface. The units know nothing about the pitch. A dry, hard January surface with long studs changes how much of that braking force goes into the ground and how much goes into a knee, and no accelerometer will tell you which. Neither will it tell you that the player did his stopping in trainers on concrete during a rehab session that nobody logged.

I am not against the data. I am against the ritual around it, where a number crosses a threshold, a session is shortened, and everyone feels they have managed something. If the threshold is built from the wrong direction of movement, the shortened session removed load that was never the danger.

The fix is unglamorous. Count the stops. Weight them by how fast the player was going when he started stopping. Then look at whether your training week ever asks a player to brake at match intensity, because most weeks do not, and then Saturday does.

You cannot prepare tissue for a force you never rehearse.