A hurdler sets the blocks from the first barrier backwards

In the high hurdles the start is not an acceleration problem; it is a distance problem with a fixed answer thirteen metres away.

A flat sprinter can leave the blocks in any rhythm that produces speed. A hurdler cannot. There is a barrier at a fixed distance and the athlete must arrive at it in a whole number of strides, on the correct leg, with enough height in the hips to attack rather than climb. Everything about the block setup is downstream of that constraint, and coaching the start as though it were a short sprint start is the most common way to ruin a young hurdler.

The stride pattern is the decision. Eight strides to the first barrier, or seven for a taller athlete with the speed to justify it, and the choice flips which foot goes in the front pedal. Get that wrong and the athlete arrives on the wrong leg and has to chop or stretch in the last two strides, which kills any chance of a clean first hurdle, which costs more than any theoretical acceleration advantage would ever return.

So the block settings serve the count. Sometimes that means a slightly narrower spacing than a flat sprinter of the same size would use, because the athlete needs to be upright earlier. Hurdlers cannot run a long shallow drive phase. They have to be tall by stride five or six, since you cannot take a barrier from a forward lean, and a coach who spends the winter teaching a low aggressive push is teaching something the event will not permit.

Here is the part that gets argued about. A hurdler who switches from eight to seven strides usually loses time for a season. The strides get longer, the athlete presses, and the first barrier gets uglier before it gets better. Plenty of coaches make the switch anyway because the seven-stride approach is what senior athletes use and it looks like progress.

I think that switch is made too early far more often than too late. If the athlete cannot hold their shape on seven, they have not gained a stride, they have borrowed one against the next twelve months.

The measurement that tells you the truth is not the block clearance or the reaction. It is the time to the first hurdle, and how repeatable it is across six attempts on a windy day.

Consistency there is worth more than anything the gun can give you.