Do a seated lateral raise, and during the contracted portion, swing your arms around straight out in front of you. You then raise them straight up over your head before you reverse your actions. Bring your arms back down in front of you, swing around to the side, then lower back to starting position. The entire start to finish range of motion is considered one rep.
I use 10-pound dumbbells on these, so don't think you'll be able to go heavy. I typically do sets of 10 reps.
We love the workouts that make you ache, the ones that make you shake your fist at the heavens above. This one involves doing one-rep maxes with 60-second negatives, followed by some nice drop sets.