Great exercise for core strength, rotational force and upper back. Remember to keep your feet on the ground, flex you glutes and abs at all times and pull your shoulder blades together, when you lift the dumbbell, You can also use kettle bells for more challenge.
Find more exercises at http://www.kiteboardingexercises.com/
KiteboardingExercises.com - or just KBX - a site dedicated to make you a better kitesurfer. And it's not just for pros. Beginners, wave riders, course racers, wave skaters, snowkiters, freeriders, new schoolers and old schoolers will all be better kitesurfers with the right training. This site will teach you how to become a stronger and more powerful kiteboarder at your level. This is the site, you can't live without if you want to progress.