Hello, in the Any% Glitchless speedrun, I noticed that they used version 1.6.4. Can I use a newer version to make the sprinting easier? Or would that be against the rules?

Any version is allowed. I’m assuming you’re talking about set seed glitchless, in which 1.6.4 is used because newer versions break old seeds, and one of the best seeds happens to be on 1.6.4.
Just remember, seeds always get broken with every new update.

Thanks a lot 🙂

Yep, since there are new biomes in 1.7, it breaks the seed.
Though the version never matters