You can perform the arnold press while standing or sitting.
If you have balancing problem, sitting will make things easier.
Arnold Press, named after Arnold Schwarzenegger – originator of this exercise, is a good exercise for complete shoulder workout and has similarity to the other press exercises.
Initiate movement by bringing elbows out to sides. Continue to raise elbows outward while pressing dumbbells overhead until arms are straight. Lower to front of shoulders in opposite pattern and repeat.
Movement should emphasize shoulder abduction while minimizing forearm pronation as this exercise attempts to combine lateral raise like motion with shoulder press. Lean forward slightly when lifting Dumbbells.
Do not arch your back or wiggle your body to help you lift the barbell.
Do not lock your elbows or allow the barbell to sway back and forth during the movement