You are fabric dye. ("color-fast" dyes do not "run", or bleed into the rest of the fabric, whereas dyes that are not "color-fast" will "run", making your nice white shirt look all blue from those new...
Only sprints have to be fast or if you are competing. For training go for distance at a comfortable pace which is less hazardous as far as potential injury.
Practice sprinting. Do short sprints, do longer sprints, do them in sets with jogging in between or do them in sets with breaks in between. Do a lot of them. Maybe do some sprinting up hills....