1. Gerontology Division, Beth Israel Deaconess Medical Center, and Division on Aging, Harvard Medical School, Boston 02215;
2. The Exercise Physiology, Nutrition, and Sarcopenia Laboratory, Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts 02111; and
3. School of Exercise and Sport Science, University of Sydney, Lidcombe, Australia