"Nearly 20 minutes after practice ended Wednesday, Dolphins running back Reggie Bush tied himself into a harness that was connected to a long set of nylon bands. Attached to those bands, a set of weights rested on the ground behind him.

This was all extracurricular: The 100-yard sprints Bush would run with those weights dragging behind him. The blocking sled he slammed against the day before. The footballs he caught that spit from the JUGS machine.

"I think it's a combination of two things," rookie teammate Daniel Thomas said. "He's trying to prove he can be that featured back. But that's just him, as well. You can tell he's just a very hard worker."

It has become plainly clear, even as Bush has been kept away from the media lately, that he understands the task ahead of him. The Dolphins' biggest acquisition of the offseason is out to prove he can do something he has never really done before.

Bush, who is expected to start Friday for what will be his first preseason action, is in an interesting situation. He's a known NFL commodity — but lacking a body of work as an every-down back has put Miami's running game into a state of unknown."