When is a long jump invalid, how is it measured, and what does wind have to do with it? The rules every jumper needs – technique, common mistakes and a practical tip.
The honest answer first: the most common reason for an invalid long jump isn't bad technique — it's one centimeter too much approach. Step even slightly over the takeoff board and the jump doesn't count, no matter how far you flew.
This gets caught by the plasticine indicator: a soft, clay-like strip right behind the takeoff board. Step over the takeoff line with your toe and you leave a visible imprint there — the judge declares the jump invalid. No judgment call, no discussion: the imprint is proof enough.
The measurement itself also follows a clear rule: distance is always measured from the front edge of the takeoff board to the nearest imprint in the sand — the spot closest to the board, whether that's your foot, your hand or your backside. Falling backward after landing costs you centimeters instantly, even if your feet touched down further forward.
And then there's wind. With a tailwind over 2.0 meters per second, a jump still counts for the competition, but not for record lists — exactly what happened to Bob Beamon in 1968 (tailwind right at the limit) and Carl Lewis in 1991, whose 8.91 m wasn't a world record due to 3.0 m/s of tailwind. Wind is measured 20 m from the board, at 1.22 m height, over 5 seconds — starting as soon as you pass the mark 40 m before the board.
Any part of your shoe extending past the front edge of the takeoff board counts as a foul. The plasticine indicator makes this objectively visible — no eye can see as precisely as that imprint.
Distance is always measured from the board to the nearest point of your imprint in the sand — at a right angle to the runway. Land cleanly forward instead of falling backward, and you secure exactly the centimeters you actually jumped.
Tailwind helps your jump, but only up to 2.0 m/s counts for records. For the competition win itself it doesn't matter — every valid jump counts regardless of wind. Only for best-list rankings and records is the line drawn sharply.
Because fouling is so costly, you practice early to find your mark: you always start your approach from the same point and adjust your step count until you reliably hit the board without stepping over it. This consistency matters more than any amount of speed.
In competition you usually get several attempts (often three in qualifying, up to six in the final) — a foul still counts as a used attempt. That makes approach consistency even more valuable: a valid jump of medium distance always beats an invalid personal best.
Avoiding fouls isn't just a rules topic — jumpers who change their stride length in the last few steps to hit the board exactly run a higher injury risk, because the body gets pulled out of its natural rhythm. Build your takeoff mark through many training repetitions rather than frantic last-step corrections.
Set yourself a checkpoint mark: an extra point 6–8 steps before the board. If you land exactly on that mark on every approach, your rhythm is right — and you'll hit the board automatically, without having to think about the takeoff itself.
The plasticine indicator behind the board shows an imprint as soon as your toe crosses the takeoff line. The jump is then ruled invalid, no matter how far you jumped — the distance doesn't count.
From the front edge of the takeoff board to the nearest imprint in the sand, at a right angle to the runway. If you fall backward after landing, that rear imprint is measured — which is why falling backward always costs centimeters.
Above 2.0 meters per second of tailwind. The jump itself remains valid for the competition but won't appear on official record lists. Wind is measured over 5 seconds, 20 m from the board.
It depends on the format — usually three attempts in qualifying, up to six in the final. An invalid jump (foul) still counts as a used attempt, which is why consistency pays off more than risk.
Long Jump: Building the Right Approach