Q: At the end of The Phantom Menace, why didn't Obi-Wan use his super-speed to run past the energy gates that kept him from Qui-Gon Jinn and Darth Maul?
A: Physical feats and acts of strength aren't always 100 percent repeatable. You may also ask why, if your favorite sports team defeated a rival once, do they not defeat them every time? Physical and mental exhaustion play a role in the use of Jedi powers. These may have hampered Obi-Wan's abilities during the duel.
- Steve Sansweet
Found at starwars.com
-> Community -> Questions and Answers. Select Episode I Lore and it's the 3rd one from the bottom. I think this is as good of an answer as you'll get from official sources.