What arm muscles r used during serving in tennis?

Question

and whats the best way 2 stregthen these muscles using 2 kilo (4.4 lbs) dumbells?

Answer 1

Entire arm, shoulder, legs and back.  Actually your entire body with all energy going into the arm and shoulder.

Answer 2

if 4.4 lbs is the most you can lift then good job, you now have the strength of a 2 month old girl

Answer 3

Your rotator cuff muscles

Use this site to focus on shoulder exercises, but make sure you do not neglect your other muscles as well:

http://www.exrx.net/Kinesiology/Inflexib...

Answer 4

Your rotator cuff muscles, and basicaly your entire shoulder, and your legs/quadraceps for power