If you are recruited, it will be with the u derstandi get that you are going to compete. A coach will be using h I 's pull to get you in, so it wouldn’t be good faith to get admitted and then not compete. Some athletes do drop out, especially if scholarship money is not an issue.
The Ivies do nit give athletic scholarships. Elite schools with top athletics like Stanford and Duke do. If you get an athletic scholarship and drop athletics you will like the scholarship, and may possibly be required to repay part or all of it.
Things to consider down the road. Right now, get things documented and in order. Also realize that if you are really that fast, an athletic recruit is by far your best chance of getting into a top US school.