Lie back on a stability ball with your dumbbells in hand. Position your feet flat on the floor with bent knees at 90 degrees. Hold the dumbbells by your chest, with your palms facing forward. Press the dumbbells directly above your chest. At the height of the extension, lift your hips by squeezing your glutes. Hold for a count, then relax your glutes, lower the dumbbells and repeat.
We love these adjustable dumbbells from Rep Fitness. They take up very little space and are also very durable compared to other adjustable dumbbells on the market.