Stand with your feet shoulder-width apart and holding a medium- to heavy-weight dumbbell in each hand. Keep your arms at your sides with your knees slightly bent and your core pulled toward your spine.
Keeping your arms straight, core engaged, and knees slightly bent, slowly bend at your hips, not your waist, and lower the weights as far as possible without rounding your shoulders or back, which should remain straight. Looking forward, not at the ground, will help you avoid rounding your back. Keep the weights close to, almost touching, your legs.
Squeeze your glutes to slowly pull yourself up. Be sure not to use your back or round your spine!
This completes one rep. Complete as many reps as you can with proper form in 20 seconds.