An adjustable reformer for exercising is provided. The reformer includes a frame, a carriage slidably mounted to the horizontal frame, and at least one resistance element connected to the carriage. A cord connects the carriage to at least one lower guide and at least one upper guide. Pulling the cord causes movement of the carriage along the frame against resistance provided by the resistance element. The guides can be height adjustable. The reformer can include a cord retraction system. Related methods of exercise are also provided.