What is the lowest level at which a human can beat the 100m world record (or: the presumed human limit) without using magic?

Optimizing a character build for fast movement in order to break the sound barrier is a well-tried source of fun with numbers in DnD. Such speed optimizations usually incorporate lots of magic and possibly additional help by allies. But I’d like to learn more about what the human body is capable of within the rules of DnD, so I’m more interested in what can be achieved without magic.

A high level Monk with two levels in Fighter and the Mobile Feat can still become ridiculously fast. If I didn’t mess up the calculations, he can run 100m in about 7.52 seconds: Use Action Surge and Step of the Wind for triple dashing to run 84m in 6 seconds, then double dash in the next round for the remaining 16m. This is even almost 2 seconds faster than 9.4s, which scientists think is the human limit (in our world, that is). But hey, it’s a Level 20 character, so becoming somewhat superhuman does kind of make sense in the world of DnD, I guess.

This raises the question: At what point in the game can human adventurers become superhuman without using magic? This is of course a more vague and general question (one could ask the same e.g. in the context of lifting strength), but let’s stick to running speed for the moment. So, my question in precise terms is:

What is the minimum level at which a human character can run 100m in less than 9.58 (or: 9.4) seconds and thus break the current world record (or: become superhuman)?

Constraints:

  • No magic.
  • No epic boons.
  • No UA (but any official rule book).

Let’s use the same approach as above, i.e. Mobile Feat + k squares Unarmored Movement + Action Surge + Step of the Wind. Since a round is 6 seconds long and a square corresponds to 1,5m, this strategy lets you run 100m in

$ $ t(k)=6+\frac{100-(48+6k)}{6+\frac34 k}$ $

seconds. Plugging in the possible values of k yields

$ $ t(2)\approx 11.333, \quad t(3)\approx 10.121, \quad t(4)\approx 9.111, \quad t(5)\approx 8.256, \quad t(6)\approx 7.524.$ $

Hence, a Monk 9 / Figher 2 is still more than half a second away from beating the world record, while gaining another Monk Level already makes her superhuman at a total Character Level of 12. Did I miss something? Or can one even do better with an altogether different strategy?


PS: A quick comment on the tricky question about Ki being magic: Since Ki is only used for Step of the Wind, we could add two Rogue Levels and achieve the same by taking the Cunning Action instead. However, this would raise the current minimum level to 14.