Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF ++ Leslie G. Portney, DPT, PhD, FAPTA ++ Dean, School of Health and Rehabilitation Sciences ++ MGH Institute of Health Professions ++ Boston, Massachusetts + ++ Mary P. Watkins, DPT, MS ++ Professor Emerita ++ MGH Institute of Health Professions ++ Boston, Massachusetts