1. Department of Medicine, MetroWest Medical Center, Framingham, MA 01702, USA
2. Department of Physical Education, Korea University, Seoul 02841, Republic of Korea
3. Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
4. Division of Sports Science, Korea Institute of Sport Science, Seoul 01794, Republic of Korea
5. Division of Cardiology, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul 03181, Republic of Korea