CommunityExerciseWhat is the best exercise for floppy upper arms? in Exercise What is the best exercise for floppy upper arms? Ihsane Q. The best single exercise for floppy upper arms is triceps dips on a sturdy chair or bench, they directly tighten the back of your arms. Do 10–12 slow reps, 2–3 sets, a few times per week for firming results. Don't let a good life slip away Start today