Are you referring to the Crimson skin of Dark-Variations skin set?
If so, search for the following elements:
<element id="Player.ProgressBar" bg="40,40,40" bdr="93,7,42" />
<element id="PlayerFlat.ProgressBar" bg="70,70,70" fg="93,7,42" bdr="55,55,55" />
<element id="PlayerSidebar.ProgressBar" bg="10,10,10" bdr="140,140,140" fg="93,7,42" />
Then replace "93,7,42"(crimson color) with "255,255,255" (white) or something similar.