Although it says on the bra medium impact it DOES NOT say so on the site which is a BIG mistake on the retailers part when they are selling SPORT BRAS!!!(HENCE THE THREE STARS) I bought them for walking AND Tennis and they do the job perfectly for walking but I have yet to try them out for tennis, but from wearing them walking it seems to me that they will work because they are nice and tight but not enough to strangle oneself :O)  The size is fine for me because reading other reviews I bought one size UP(thank god for reviews or I would have bought my regular size and then they would have been too tight) They are in the laundry basket so we'll see how they wash up. I hope they don't lose their shape, but I think they will keep their tightness  because they seem to be well made. Anyway all in all they are definitely GREAT value for money.