PT management commonly includes prescription of or assistance with specific exercises, manual therapy, and manipulation, mechanical devices such as traction, education, electrophysical modalities which include heat, cold, electricity, sound waves, radiation, assistive devices, prostheses, orthoses, and other interventions. In addition, PTs work with individuals to prevent the loss of mobility before it occurs by developing fitness and wellness-oriented programs for healthier and more active lifestyles, providing services to individuals and populations to develop, maintain and restore maximum movement and functional ability throughout the lifespan. This includes providing therapeutic treatment in circumstances where movement and function are threatened by aging, injury, disease or environmental factors. Functional movement is central to what it means to be healthy.