different mechanics, different energy systems —
sure, for recreational purposes, by all means, have fun, but I can’t see how for a sprinter it would make any sense to regularly include mtn biking as part of your training, even for cross training/general prep.
PS - Chain yourself to the squat rack. squat. a lot. lather, rinse, repeat.
deep squats, deadlifts, snatch-grip deadlifts, roman deadlifts, reverse back extensions, back extensions to some extent, cable pull throughs. If you have a foot strap for the cable you can do hip extensions, same motion and a glute-isolator.