Procedures

The study was conducted in compliance with the Declaration of Helsinki and approved by the Ethics Committee of the Medical Faculty of the University of Groningen (January, 2016). Written informed consent was obtained prior to testing.

Testing was conducted under supervision of one researcher with help of two other experienced test leaders and took place during the Dutch National Championships or prior to a training session. During the testing session, the players executed the BRIT and filled in a questionnaire about badminton related activities over the past eight years, including hours of training per week and starting age. Not all players completed all test components of the BRIT and the questionnaire due to limited time or unwillingness to do a physically demanding test (badminton-specific component BRIT) prior to match play.