1. Geriatric Research, Education, and Clinical Center, George E. Whalen VA Medical Center, Salt Lake City 84148, USA.
2. Department of Exercise and Sport Science, University of Utah, Salt Lake City 84148, USA.
3. Department of Physical Education, Dong-Eui University, Busan 614-714, Korea.
4. Department of Sports Science, Pusan National University, Busan 609-735, Korea.