1. Department of Rehabilitation Medicine, Graduate School of Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan
2. Department of Rehabilitation Medicine, Nippon Medical School Chiba-Hokusoh Hospital, 1715 Kamakari, Inzai, Chiba 270-1694, Japan
3. Department of Rehabilitation Medicine, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
4. Department of Physiology, Faculty of Medicine, Kindai University, 377-2 Ohno-Higashi, Osakasayama, Osaka 589-8511, Japan