Stand on a raised platform or plates with feet wider than shoulder-width and toes slightly turned out. Position a barbell over your mid-foot, hinge at the hips and bend your knees to grip the bar with hands inside your legs. Brace your core, keep your chest up, and push through your heels to extend hips and knees, lifting the bar while keeping it close to your body. Stand tall, then lower the bar back down under control to the deficit. Repeat for reps.
Log your barbell sumo deadlift from deficit sets in 1RM.fit and watch your estimated 1RM update automatically as you get stronger.