This exercise is great for upper body, biceps and lats. To perform it you will only need an exercise ball and one dumbbell.
Kneel on a fitness ball with one leg. Place a dumbbell in the opposite hand with arm fully extended. Position other hand on a ball to balance your body.
Slowly bring the dumbbell upwards so the angle in elbow forms 90 degrees. Return weight to a starting position. Keep your arm by your side throughout the exercise. Repeat.