How much cardio stimulation before the body adjusts?

[Lex]

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?

 

[Madmick]

I think significant muscle recruitment adaptations regarding the anaerobic lactic system take place within the first two weeks (for athletes new to an activity). Then they diminish almost completely after two months (for experienced athletes).

 

[Brendon Katz]

yeh , when u first start a new activity your body learns to do it more effectively so gains are real good for a month or two. then it takes 8 -12 weeks for vo2 max and fitness to improve.