i actually have something called a "boing" that i used to use with patients that is similar, but you can do a wider variation of movements. the principle behind it is strong, since you recruit a lot of different muscles to stabilize while you do it. but you really can do just about the same thing by holding your hands together and imitating that motion.

at 24, you should be able to get your sexy arms back! but remember that there is no spot-reduction; if you have fat on your arms, you have to lose that before you can sculpt them.