What disadvantages would a freakishly tall sprinter have?

Usain Bolt is pretty tall (6ft 5in), but a lot of other very fast sprinters are not that tall. Tyson Gay and Yohan Blake are both under 6ft, to pick his two likely closest rivals.

Not knowing much about the mechanics of sprinting, I would think a long stride length would be a pretty major advantage in a short sprint. So why aren’t any freakishly tall 7ft+ giants doing great things on the running track? Is it a question of limbs becoming too ungainly to move quickly enough above a certain length, or is it just that height is not a sufficiently great advantage compared with other factors?

Short sprints are all about quick acceleration as well as how long the sprinter can hold his top speed.
That’s what is so startling about Bolt. He’s far quicker off the line than is typical of very tall men.
Then when you combine his turnover with a longer stride and you have some crazy WR times.

Heard a report on NPR last night about a change in thought about sprinter’s body types. Bolt has a mechanical advantage over shorter runners due to his stride length, and they think that taller sprinters will become the norm. As they teach a slightly more efficient running style for taller runners you’ll see stride length increase and frequency decrease. Bolt averages 3-4 fewer strides in the 100 meters than many of his competitors.

Where the extra height becomes a disadvantage isn’t clear yet, but I suspect you’ll see some taller sprinters yet.

runner pat sums the issue with tall sprinters up quite nicely. Generally, tall sprinters take longer to come out of the blocks. You basically drive yourself out of the blocks and into an “up” position. If you are shorter, it takes you less time to get to the “up” position. A shorter sprinter may not have the stride length of taller sprinters but they hit full stride faster than their taller competitors. I can see taller sprinters becoming more common as people start recognizing that they are just as capable of competing at the highest levels in sprinting events as they are in distance and jumping events.

Bolt is an incredible sprinter to watch. So excited for the start of track and field today!

What disadvantages would a freakishly tall sprinter have?

He’d bang his head on doorways a lot. He’d have a hard time finding clothes that fit.

Here’s the NPR show - http://onpoint.wbur.org/2012/08/01/perfect-physiques

Hear, hear.

I think I just got your username.

Well, at some point, their heads will be high enough that the reduced air density will lead to oxygen starvation.

Should it be Sicks Nein?

Isn’t some of the slow start just the result of discouraging tall runners from sprinting? I don’t see any reason a tall sprinter couldn’t get off the blocks fast enough to outdo a shorter legged runner over distance with the extra stride length if they trained to do it. Maybe something short enough like a 50 yard dash doesn’t help, but I don’t even know if that’s a competitive event anymore.

His feet would hang out the bottom of the bed.

He’d have a hard time getting comfortable in economy class.

A truly freakishly tall sprinter could just push off the blocks and immediately fall forward, crossing the finish line.

Here’s an article that explains it better than I can.

And the 60m is run indoors.

I was just talking about his speed out of the blocks as a factor. I’ve never doubted his longer legs helped him at full stride, but the power explanation of that part is interesting.

That was addressed in the comparison with a short gymnast, it just takes longer for the longer limbs to get up to speed. Once he’s there, look out!

See, that’s where I don’t think there’s a significant difference except for a short race. Part of it has to do with training. Long legged runners may need an optimized stance, and to train specifically for the rapid start. If they get ruled out of sprinting when they start to get tall, they won’t develop that.

It’s not just technique: there’s sound physics to it. All all things (including proportions) equal, a longer leg will have muscle cross section (and therefore force) that goes up as the square of length and mass (therefore inertia) that goes up as the cube of length.
Simply, as the link says " smaller people can exert more force in relation to how much they weigh".

At top speed, stride length outweighs this, but nobody is surprised that a rabbit is quicker off the blocks than a horse.

Agreed. But getting back to where I started on this, tall runners may be discouraged from sprints early in their career and not develop the fastest possible start for their size.