How To Perform The Seated Dumbbell Overhead Press
Grab two dumbbells and set up on an incline or seated bench. Make sure your back is pressed all the way into the vertical pad.
Flare your elbows out. Your face should be facing the ceiling and your palms facing forward. Also, make sure the dumbbell is set very deeply in your hand so your wrist stays in a strong position for the entire set.
Press the dumbbells up toward the ceiling, fully extending your elbows. Do not hyperextend or lockout your elbows as this is dangerous for those joints. The dumbbells should travel in an arc-like curve. With the dumbbells converging at the top of the ramp. There's no need to touch the dumbbells together at the top, but there's nothing wrong if they do.
After extending your elbows, begin the eccentric portion of the rep. Make sure your upper arm at least reaches parallel with the ground before initiating the next concentric. If you have the shoulder mobility, you can go all the way to the point the dumbbells tap your shoulders. This may give people with shoulder issues some pain. If it does, cut the range of motion a little shorter.
Make sure your back stays flat against the vertical pad for the entire set. There is a tendency to begin extending the spine when fatiguing on an overhead press. Your nervous system understands that you are stronger pushing horizontally than you are pushing vertically. And so it will begin to point your chest up toward the ceiling to try to involve your pecs. Don't let this happen. A hyperextended spine with a weight pushing straight down from overhead will place a lot of unneeded stress on your lumbar spine.