McCall heaped praise on the midfielder after the 28-year-old helped influence an unlikely comeback win at Torquay last Saturday, which helped his side to their first win since early December.
The Bantams boss told the Telegraph & Argus: "In both games where he has played 90 minutes, Omar has got stronger as time has gone on.
"When we first came to the club he couldn't play three games in a week. You'd have to take him off after 60-65 minutes because he physically wasn't up to it.
"So credit to him and the medical staff for working so well on his fitness. He has come back in brilliant condition. He is such a threat with his pace and ability, even more so if he can still do it towards the end of the game when opponents are tired."