Excellent form? Do you keep the length of the dumbbell parallel to the length of your body or do you keep it perpendicular or some combination? Also is your torso fairly parallel to the ground or are you bracing on something that causes it to be angled?
Well, I guess "excellent" form is contingent on the person's body mechanics. I guess there really is no such thing as "excellent" form from an objective standard. Thus, I do what is most comfortable for me.
I prefer to brace myself on the dumbbell rack, so my back is slightly angled. Ive always felt lower back pain when I put my leg on a bench and my back was completely parallel. As for my arm movement, I DO NOT let the dumbbell go in a straight up and down motion. My arm sort of starts more at an angle in front of my body, then I row back to my hip.