Begin sitting. Extend and lift your legs, leaning back onto your tailbone while keeping your chest lifted. Flex your feet back towards your face to engage your quads and press your legs together to engage your inner thighs.
With a dumbbell in each hand, extend your arms out in front of you with a slight bend at the elbow, palms facing up. Keep your core tight and pulled in to your spine.
With control, bend your elbows and curl the dumbbells toward your face. Keep your elbows high and core tight throughout.
Extend the arms to return to the starting position. This completes one rep.
Do as many reps as you can in 45 seconds while maintaining proper form. You can modify the movement by bending your knees or dropping one or both of the weights.