Why do people believe shorter people have an advantage in distance running?

They don’t necessarily have an advantage. That is not a fact. And to your point runners like Bolt (6’5) and Mu (5’10), Jacob Ingebrigtsen(6’1) are clearly the top in the world and are tall

Probably has something to do with impact forces on the joints/bones/ligaments/tendons.

If you'd drop an ant 20 ft it'll be fine, if you drop a mouse 20 ft it'll probably live but if you'd drop a cow 20 ft you'll have some cleaning up to do.

Mass is ^3 while surface area of (let's say) your bones is ^2.

You may not like it, but it is true. List the height of the top 25 marathoners of all time. The average is 5'7".

Even if that’s true, that doesn’t explain WHY. It could easily be that shorter guys gravitate to distance running because they are unlikely to do well in other sports. That doesn’t mean they have a physical advantage in distance running.

Oh, and I don’t like or dislike it (I’m 5’10’’). Just trying to understand the thinking.

While it is true that there are good distance runners who are taller, when looking at the best 5k - marathon runners, the vast majority will be shorter / smaller .

It’s usually the non-running observer who opines that a taller person with long legs must have an advantage because they’ll naturally have a longer stride.

It is interesting that being shorter seems to be preferable in the sprints, but there are several outliers. Then, in the mid-distances, there is not a clear advantage either way. Then, 5k and up, the advantage is for the shorter folks, but with exceptions.

I think it has to do with the forces and torque required for each stride and the great number of strides required for a distance event. I have no idea why the sprints are the way they are, however. Perhaps the shorter people are able to get out faster with their shorter quicker strides. The tallers have a greater top end speed, but it is usually too late. In that case, though, it would seem that tall guys should dominate the 400, but the quarter looks more like the mid-distances, where it is not clear to be advantageous to be shorter or taller.

I assume at longer distances the same reason small cyclists do well applies. Power to weight ratio. Smaller dude has less power, but the weight savings disproportionately save energy. Ratio is better.

Has to be a power-to-weight issue on some level. Many elite long distance runners are tiny.

Sub 10K is less of an issue to be bigger.

Interesting you mention Bolt. I just read this:

Research shows that an amateur runner often takes between 50 and 55 steps to complete 100m, while an elite sprinter takes in the region of 45.

Bolt typically completes a 100m race in about 41 steps - three or four fewer than his rivals.

bbc.com

How does Usain Bolt run so fast? - BBC News

https://www.facebook.com/bbcnews

Usain Bolt showed his dominance of men's sprinting at the World Athletics Championship in Beijing this week with wins in the 100m and 200m. What's his secret?

Link:www.bbc.com/news/magazine-34089451.amp

Thanks. I’m not familiar with power to weight ratio. I’d like to understand this more. If weight is proportional to height, it seems like it would balance out. Forgive me: science was never my strength!

Lighter folks have less weight to carry, and shorter folks less height to carry.

well with billions of people trying this experiment, and most of the best (kipchoge, bekele, gebreselassie, farah etc) all being roughly 165-170cm tall, that must be the sweet spot. if it were better to be 180-185cm, then runners of that height would dominate, but they don't.

and i know there are many runners of about 180cm tall that are exceptional talents and have won olympic medals and such, but they aren't the very best like the names above.

Shorter people usually weigh less. Less energy cost over long distances.

Small people also dissipate heat much more efficiently, and internal temp is a known endurance limiter.

These advantages are most prevalent in 10k and above.

running economy - it's more important relative to things like vo2 max and anaerobic power the longer the distance becomes, which is why it doesn't matter for bolt and ingebrigtsen. running economy and lactate threshold are most important for marathon distance.

the bigger guys might have longer stride length but they're using more energy to take those strides because they have more mass above their legs to move.

I believe surface area plays a large part. Shorter people have more skin (surface area) relative to their height. This allows them to cool more efficiently. This matters a lot more for things like half and full marathons as opposed to 5 and 10ks.

Why can a cat outrun me if I have longer legs?

that's not about leg length, it's because the cat has more time in contact with the ground to propel itself forward

Not shorter; relatively smaller. It's a power to weight ratio thing (and some tweaks like stride length). That's the danger in emphasis on body weight; it's not just weight, but that's involved in the equation. I put out tons of power, but I'm also pretty heavy, so I'm slow.

It isn't proportional. That is why BMI is calculated by dividing weight by the square of height rather than by height.

It's multi-factorial, but one factor is that even across people of similar BMI, shorter people have a more favorable body surface-area-to-weight ratio, which allows for more efficient cooling. Better temperature management = faster times.