The pilates reformer was invented by Joseph Pilates, and it consists of a bed-like frame with a flat platform (called a carriage) on it that rolls back and forth on wheels. The carriage is attached to the frame by springs at varying tension, allowing the practitioner to push or pull against varying levels of weight. Exercising on the reformer is very much a resistance and strength training workout that will help improve mobility, flexibility, and balance. Many mat pilates exercises can be done on the reformer with the added support of the springs, however, the spring load can also make many exercises feel more challenging and destabilizing.