Position yourself on a hyperextension (Roman chair) bench with your hips supported and feet secured. Hold a dumbbell close to your chest or across your arms. Start with your torso lowered by hinging at the hips while keeping your back neutral. Then raise your upper body by contracting your lower back and glutes until your body forms a straight line. Slowly lower back down under control and repeat.
Log your dumbbell hyperextension sets in 1RM.fit and watch your estimated 1RM update automatically as you get stronger.