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Acceleration or top speed — which is your athlete missing?

Two athletes with the same 100 time can need opposite training. One test session separates them.

Two sprinters run 11.9. The first is gone at the gun and gets reeled in over the last 30 metres. The second is nowhere at 20 and passing people at 80. They have the same result and almost nothing else in common, and a programme written for one of them will waste the other's season.

Two numbers, not one

Separating them takes two measurements taken the same afternoon.

• A standing or block start over a short distance (10 to 20 metres), which is almost entirely acceleration.
• A flying segment with a proper run-up, which is almost entirely maximum velocity.

The comparison between them is the diagnosis. An athlete whose short start is strong relative to the group but whose flying speed is ordinary is an accelerator who runs out of road. One whose start is unremarkable and whose flying speed is high has the engine and cannot get it going.

Running it with gates

Two phones, spacing typed in, one segment per run. Do the acceleration test first while everyone is fresh: gates on the start line and at 20 metres, from blocks or a standing start. Then rest properly and do the flying test: a 30 metre run-up into a 20 metre measured segment. The speed comes back in metres per second for both, which is what makes them comparable: a time over 20 metres from a standing start and a time over 20 metres at full speed are not the same quantity, but their speeds are.

Do it for the whole group in one session and you get something more useful than any individual number: a ranking on each quality separately. The athlete who is eighth on acceleration and second on top speed is the one whose training you should change on Monday.

What the film adds

A gate tells you the athlete is slow out of the start. It does not tell you why. That is what the Film Room's block start setting is for: it reads the first six steps and reports the drive-phase trunk lean and whether the athlete stands up early, whether the hips climb instead of driving out, and back-leg extension at clearance. Standing up too early is the single most common reason a strong athlete accelerates badly, and it is invisible at full speed and obvious on a clip.

One measurement session is a snapshot, not a verdict. An athlete who tests badly on acceleration the week after a growth spurt or on a cold evening has told you about that week. Repeat it before you rewrite anybody's programme.

The point of splitting the two is not the numbers. It is that "get faster" is not a coachable instruction, and "you are losing the race in the first 20 metres" is.

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