From the University of Puerto Rico, School of Medicine, San Juan, Puerto Rico.

All correspondence should be addressed to: Walter R. Frontera, MD, PhD, FRCP (Lond), Department of Physical Medicine, Rehabilitation, and Sports Medicine, University of Puerto Rico School of Medicine, PO Box 365067, San Juan, Puerto Rico 00936-5067.

Financial disclosure statements have been obtained, and no conflicts of interest have been reported by the authors or by any individuals in control of the content of this article.