- The extent to which health limits physical activities (e.g., self-care, walking, climbing hills and stairs, bending, lifting, moderate and vigorous activities.
- McHorney, C. A., J. E. Ware, and A. E. Raczek (1993), "The MOS 36-Item Short-Form Health Survey (SF-36): II. Psychometric and clinical tests of validity in measuring physical and mental health constructs.", Medical care, 31, 247-263. [Endnote]