What would you guys recommend to someone who wants to get better upper arm strength? I play tennis a lot, so my forearms are a LOT stronger then my upper arms, and that's starting to bother me a bit. (I look somewhat strong there, but I'm not nearly as strong as I want.) I'm about 5foot 6inches, and still growing. (I'm 14, so I hope to grow a lot more, as it'd do wonders for my serve...) I have acess to no gym really, but I have dumbells ranging from 2-20lb to start with. (I'm not entirely sure if it stops at 20 though, because it says on the box fourty pounds, but looks like it could only hold about 20 on it, but there are two of them, so I would assume it's just a 40lb sum. It's one of those add weight to the dumbell bar as you go.), along with a 12lb medicine ball. I am one of the people that has a lot of arm problems and such, so I can't really always do what I want. I just recently got the set of heavier weights in an attempt to get a bit stronger. I used to use 5lb weights once in awhile for curling, but not too much. :/ What would you guys think I should do to start out? (just try to do more basic push ups?) I used a rowing machine a bit last summer, but that jacked up my shoulders for tennis. (I play a LOT of tennis, so my arms can get stressed out a bit too easily. I'm someone who practices like 5hours a day during the week. Should I just kind of pray that it will strengthen them by itself over time?)
If it means anything, I can run too. (I run distances) I run a path of about 3 1/2 miles every few days. Sprinting would probably be better at strengthening my arms though, wouldn't it?