Yes, as with any exercise program the results are often determined by the frequency and effort involved. A well designed chair exercise program should incorporate many of the same muscles and exercises as a standing program. Practically all of the traditional strength and cardio movements can be emulated in a chair with some creativity.
Fortunately, with chair exercising because you are sitting less stress is on the lower body such as the lower back, knees, ankles and feet because they do not have to support the weight of your upper body. As a personal trainer I am noticing more people are requesting, chair exercise programs, such as chair-a-cise, because it prevents or reduces injuries to their ligaments, joints and tendons making exercise more comfortable and safe.