Overhead
 

exercise you can do while standing or sitting is the dumbbell overhead extension, one of the best exercises for targeting the long head of the triceps. According to your taste, do this exercise while holding a dumbbell in one hand, or both, or use both variations.

Begin by lifting the dumbbell over your head. Lower it behind your head as close to the middle of your back as you can, safely return to its starting point with arms straightened above your head and repeat