How many sprints would you have to do before the body starts to react and make adjustments, such as metabolic level, muscle stimulation, that kind of stuff. Could you do 1 100m sprint in 20 seconds... then 2 days later do in in 19 seconds... I have no idea how long it should take since I've never done one since grade school.. Would it take 5 100m runs in a row before the body decides to make adjustements... In a sprint situation.. would the body adjust muscle size first which should lead to a better metabolic level.. or BMR, I think it's called. What's the minumum it takes?