Can Arm Weight Be Used While Using Implanon ?

Hi Doctor, I am on my third Implanon and 2 years in so one year to go. This so is my 8th year at present. I really do not think I want children but will not rule it out in case I change my mind. But single at present. Would it be ok to continue it after it expires, Nov 2011 and insert a 4th? I am 37. Also could I use arm weights with it? Thanks. Orla