Originally Posted by dealt_with
You're not gonna lose hand speed but it's about as un-sports specific as you can get, it's not going to do much at all for your boxing fitness.
Former champion, Juan "Baby Bull" Diaz, never ran, he was on the stairmaster and in the swimming pool. It worked for him, but is it for everybody, that I can't say. Diaz never had a hand speed, or stamina problem.