1. Department of Medicine, University of California San Diego, La Jolla, California;
2. Department of Internal Medicine, Division of Geriatrics, University of Utah,
3. Department of Exercise and Sport Science, University of Utah, and
4. Geriatric Research and Clinical Center, Salt Lake City Veterans Affairs Medical Center, Salt Lake City, Utah
5. Nuclear Magnetic Resonance Laboratory, Association Institute de Myologie-Commissariat à l'Energie Atomique, Institute de Myologie, Pitié Salpêtrière University Hospital, Paris, France; and