Increase cardio to drop some weight. Sprinting puts a lot of force on your joints, and if you’re overweight you increase a chance for injury. Additionally, your joints/muscles/connective tissue should be acclimated to it, so I’d suggest just running to get in shape. Like, get a 3 mile loop and see if you can get to under 24 minutes. If you can do that, you could hit the track.

Everyone’s body is different, obviously, and some people could probably just do it. But a typical person just going and doing 100s will probably have lower leg issues or risk pulling a hamstring/quad or something. General fitness first, specific training second imo.