The beanbag is essentially a weighted bag of beans, sand or gravel, attached to a 12- to 18-inch dowel with a long cord.
During the roll-up exercise, the bag is held away from the body at shoulder level, and you are required to maintain a very specific, whole-body stance. Fingers, hands, wrists and forearms are strengthened as you unwind and rewind the cord around the dowel.
Sounds simple, right? It is—except that performing the entire sequence, even once, is exhausting.
How did Mr. Pilates know 80 years ago that our computers and handheld devices would stress out our fingers, hands, wrists and forearms, or that 21st century weekend warriors would develop a plethora of overuse stress injuries in the upper body?