1. Department of Physical Therapy, Faculty of Health Sciences, Hokkaido University of Science: 7-15-4-1 Maeda, Teine, Sapporo, Hokkaido 006-8585, Japan
2. Graduate School of Information Science and Technology, Hokkaido University, Japan
3. Institute of Gerontology, The University of Tokyo, Japan
4. Sapporo Syuyukai Hospital, Japan