ArticleCellular Control of Bone Response to Physical ActivitySmith, Everett L. PhD; Clark, Wendy D. PhDAuthor Information Department of Population Health Sciences, University of Wisconsin – Madison (Dr Smith); and the Pacific Agri-Food Research Centre, Agassiz, British Columbia, Canada (Dr Clark). Corresponding author: Everett L. Smith, PhD, Department of Population Health Sciences, University of Wisconsin – Madison, 1300 University Ave, Madison, WI 53706 (e-mail: [email protected]). Topics in Geriatric Rehabilitation: January 2005 - Volume 21 - Issue 1 - p 77-87 Buy Abstract Although physical activity results in an increase in bone mineral density proportional to the applied strain, the mechanistic control of bone cellular response to mechanical loading is not clearly understood. It is hypothesized that changes in bone cell metabolism and morphology occur along the lines of induced strain that results in an increased bone mineral density and an increased resistance to fracture. Changes within the bone cell are dependent on the frequency, strain magnitude, and strain rate of the mechanical stimuli as both osteocytes and lining cells are sensitive to modulations of mechanical load. It is further hypothesized that osteocytes and lining cells have sensors within or near the cell membrane where mechanical strain, fluid or pressure shifts, or electrical charges are transduced to a biochemical signal. An understanding of the mechanisms and the type of loading required to initiate bone cell response is important in maximizing maintenance and therapy for the prevention and/or treatment of osteoporosis. © 2005 Lippincott Williams & Wilkins, Inc.