In the last chapter where it talks about 100m champions of the future. It says one scientist says the limit is 9.4. Another says 8.99. Then it says Weyand thinks someone can run 5… I assume he means via genetic modification of human tissue.
Weyand bases this on his formula which predicts humans have the potentail to run at speeds up to 50 or 70kph. I think he needs to look at his formula because that is quite a big difference so its not very accurate. Also Weyand bases this on vertical force production.
Ward-Smith predicts 9.3s if I remember correctly.