While this may by fun, it's contradictory to a lot of real-world-simulation-type-logic. It's actually fairly rare for a human to be able to increase would be called DEX without increasing what would also be STR, or vice versa. Faster running, faster punching, and faster dodging are really all about growing different muscle groups. The extreme ends the spectrum like huge linebackers or lithe figure skaters are just that - extreme outliers.
Now, I do like the idea that different species could use something like this as an alternative to ASI. Orcs must have STR that is 2 higher than DEX. Dwarves cannot have a DEX higher than their CON. Gnomes must have an INT that is higher than their WIS. Humans must have their STR and DEX no more than 6 apart. That has a lot of potential to differentiate species while still allowing a wide range of options. But now we're also into ASI discussions.