Knowshon Moreno lifted his chin over the pull-up bar for his final repetition — of 45 — and collapsed into a sweaty, out-of-breath heap on the floor of the CrossFit Verve gym in North Denver.

Moreno, the Broncos’ third-year running back, had just cranked out 45 “thrusters” — an overhead press with a 95-pound bar — and those 45 pull-ups — broken up into sets of 21, 15 then 9, all in 3 minutes, 39 seconds. That time is considered elite by CrossFit standards, and shows an improvement of 4 1/2 minutes from when he first did this fitness test six weeks ago.

“I want to come into the season in the best shape I can be. I want my body to be in great shape so I can go out there and practice hard, practice to the best of my ability,” Moreno said.

Little has gone as planned for Moreno in the past two seasons since the Broncos drafted him at No. 12 overall. He suffered a knee injury during his rookie training camp and dealt with two serious hamstring injuries last year. On the field, he has yet to live up to the hype that comes with being a first-round pick. Moreno has not yet had a 1,000-yard season, nor has he emerged as a big-play threat, with only three runs of more than 20 yards last season.

Moreno understands the criticism, and said he uses it as fuel, especially with the Broncos on the verge of adding another running back through free agency to compete for playing time, if not the starting job.

Moreno said he encourages the idea of adding depth to the backfield, even if it means sharing carries. He pointed to new coach John Fox’s track record with a run-heavy offense in Carolina, where in 2009 DeAngelo Williams and Jonathan Stewart each rushed for more than 1,100 yards. Williams will be an unrestricted free agent and is among the running backs the Broncos could sign.

“It’s always good to have more people on the team that can help out. You shouldn’t look at it like, ‘Oh, damn, someone else is coming in,’ ” Moreno said. “You should look at it as a challenge. If you’re not going to compete, you shouldn’t be playing this game.”

Moreno joined Broncos teammates for a workout at Valor Christian High on Thursday morning, but nearly all of his offseason work has been done at CrossFit Verve, a cavernous room filled with pull-up bars, barbells, weight plates, medicine balls, still rings and large ropes. When he arrived for the first time in early June, he could do only 14 pull-ups. Now he can rip off 40 without a break.

Moreno is noticeably leaner, especially in his face and torso, having dropped from 215 to 200 pounds, but trainer Matt Chan said Moreno has gained strength in his back, glutes and especially in his hamstrings, both of which were injured in 2010.

“He is absolutely stronger,” Chan said.

Now Moreno just wants to be able to show it.

“I know I’ve got more in me,” he said.

Lindsay H. Jones: 303-954-1262 or ljones@denverpost.com