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Comment by ck2 | Hacker News Reader

Even elite marathons now are almost always ending in sprint finishes which is a bit dumb but an obvious problem. The women's olympic marathon was won by less than 3 second after more than 26 miles?

Photos no matter how fast still require human objectivity in evaluation.

Instead there should be some digital signal or laser reflection that is precise?

I don't like the rule where it's any part of the athlete's body first to cross the line, it should be the first athlete to ENTIRELY cross the line, no part of them still remains before the line, not even their trailing foot.

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> it should be the first athlete to ENTIRELY cross the line

No, because then you'd be changing the distance of the race.

Runners start behind the starting line. So for consistency, they finish when the first part of their torso passes the finish line.

Your suggestion would only make sense if they started with e.g. their trailing foot touching the starting line and the rest of their body in front of it. But that's not how they start.

Also, if you based it on foot position rather than torso position you'd be introducing a rather random element, since it would change based on what part of their stride they were in. Torso position is much more continuous, and therefore is a far more accurate assessment of athletic ability.

Do they start with their head behind the line? If so that's really running 100m + 1 head. The distance is completely arbitrary anyway so it doesn't really matter.

> Instead there should be some digital signal or laser reflection that is precise?

These photo finishes are really precise. 40k FPS, that's 25 microseconds, or about a quarter of a millimeter in distance (at 10m/s running speed). If you look at it, with the lines drawn, it is very obvious who's won.

The organizers took some time to double check everything since it wasn't obvious from the naked eye, but with the photo finish there is absolutely no ambiguity. In fact, the photo finish is 400x more precise than what is required here.

> I don't like the rule where it's any part of the athlete's body first to cross the line.

It is not the case, the article says the torso matters, not "any part". Also, the athletes stand completely behind the starting line, it makes sense that the race ends just as soon as they touch the finish line, otherwise it wouldn't be 100m but 100m + one body length.

> any part of the athlete's body

I think it's any part of the athlete's torso, which corresponds to the red lines on the image.

Though I wonder if a runner could gain an advantage using very long breast implants?

The marathon case is interesting.

The top two runners in a marathon keep pace with each other, both know that they're holding some energy in reserve for the final sprint. Perhaps one sprinter could try to push themself a little faster throughout the entire race, but I suspect the consequences of running a little over your optimal pace are worse than running a little under your optimal pace, so they err on the side of running a little under their optimal pace and save energy for the final sprint.

Yeah, it's interesting to see techniques from short track (skates) or bike track to be used in so extremely different type of run. But after some thought, it's obvious that any long distance run can be divided into phases with different characteristcs and strategies can be built on top of it.

Long-distance running races pre-date cycling and skating by decades. If anything, it's strategies from running that inevitably find their way into more modern sports.

This is why world records in long-distance running are not typically achieved at big events, where winning is all that matters.

They are usually attempted at smaller events, coordinating with other runners ("hares") to achieve the perfect pace, without having to worry about the result (hares will typically drop out throughout the race).

If you want to see what happens when the favourites run a little too hard a little too early, check out the 1500m final: Ingebrigtsen and Kerr were supposed to slug it out between themselves, but they both pushed too early (Ingebrigtsen unwisely pulling from the front most of the time), so they got to the sprint too tired to match the surging Hocker.

> I don't like the rule where it's any part of the athlete's body first to cross the line, it should be the first athlete to ENTIRELY cross the line, no part of them still remains before the line, not even their trailing foot.

What's the difference?

it should be the first athlete to ENTIRELY cross the line

a) Why entirely across, and not just the first to touch the line?

b) I get that basing it on the whole body feels a bit more objective, but it would probably also lead to people diving over the line to gain a few milliseconds. As well as looking a bit silly it could be dangerous. The lean through a (now virtual) tape at chest height is traditional.

I could see bigger people at a disadvantage so is it fair? Please show your work in the form of a myth busters episode, and figure out how to work some form of explosion in.

Digital signals and lasers aren't any better. There are lots of errors that can be made that change the measurements.

Photo finish is one of the best methods.

Where is the difference between first body part crosses the line vs the whole person?

It's still hard to know who has won in a photo finish.

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