Rumble Training Flatiron/Chelsea workouts deliver 10-round, 50-minute of two training styles: half of the class is spent on custom treads--sprinting, climbing, pushing-- and the other half is spent with a variety of resistance tools-- pressing, pulling, squatting, crunching, and jumping. The intervals are authentic and intense, the activities are varied, and the sweat is real. Rumble Training is a fresh, fancy, fun new way to fitness.