Moving a character that is not vertically oriented straight up.

While I am just familiar enough with the Move and Rotation tools to achieve successful edits, I’m still new to animation in general, so I may be about to ask about a tool or technique that doesn’t exist. My apologies if that is the case. I’m looking for a way to move a character straight up from the floor of a scene within a range of frames within a clip, that does not involve moving all three of the position axis by hand. Even though the Move tool has a center grab point that I can use, it also lets me accidentally move the character off to the side as I attempt to move it straight up. 

Because the clip I am editing moves the character in an exercise routine, all of the position axis are constantly changing. Other than adjusting all three axis for every frame I need to adjust, is there a variable, or a control that moves a character strictly vertically other than dragging the character up with the center of the move tool and in all likelihood, having to go back and forth until I get it just right? 

Thanks for your time.