Kotaro Suzuki, Faculty of Health and Sports Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8574, Japan
Author contributions: Suzuki K collected all documents, reviewed the published articles, and wrote the manuscript.
Conflict-of-interest statement: The authors declare no conflict of interest.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Kotaro Suzuki, PhD, Faculty of Health and Sport Sciences, University of Tsukuba, 1-1-1 Tenoudai, Tsukuba, Ibaraki 305-8574, Japan. email@example.com
Telephone: +81-29-8532734 Fax: +81-29-8536507
Received: April 17, 2015
Peer-review started: April 21, 2015
First decision: May 13, 2015
Revised: July 18, 2015
Accepted: September 10, 2015
Article in press: September 16, 2015
Published online: November 27, 2015