Track sprints recruit fast twitch muscle fiber, which requires more fuel for recovery than do slow twitch (endurance aerobics) fiber. The fuel will come from fat stored in your legs. And a track sprint is just that: your hardest, meanest, most explosive sprint for 30 seconds or less. If you can run beyond 30 seconds, you're not running your fastest. Do eight sprints with 2-4 minutes of casual walking in between for recovery.
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