The search terms from each category were combined to locate all relevant literature using the following databases: The Cochrane Library; MEDLINE: EMBASE, CINAHL; Sportdiscus, AMED, a PsychInfo. The clinicaltrials.gov registry was also searched to identify trials that were not yet published but that had relevant outcome data available. Slight variations in MeSH terms and keywords were used depending on the database being searched (Table 1 provide a full list of search terms used to search the EMBASE database). the search was not restricted by date. The search was last updated in April 2014.