Seated Weight side to side Twist

Setup
Sit on a mat with knees bent, leaning back at a 45 degree angle, holding a dumbbell overtop waist with elbows bent.
Movement Instructions
Rotate upper torso 90 degrees with dumbbell, keeping elbows bent and forearms extended parellel with weight, until shoulders are facing perpendicular to body. Then rotate upper torso forward 180 degrees until shoulders are perpendicular facing opposite side of body, keeping elbows bent with dumbbell extended. Rotate forward 180 degrees and repeat.
Comments
Rotate upper torso from waist, keeping weight in line with torso, and never rotating upper arms from shoulders.