1. Physiology Division, Yokohama City Sports Medical Center, Yokohama 222-0036;
2. Sato Institute for Rehabilitation and Fitness, Tokyo 183;
3. Urafune Hospital of Yokohama City University, Yokohama 232;
4. Tanaka Women's Clinic, Tokyo 158; and
5. Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan