Review of European Studies; Vol. 5, No. 5; 2013 ISSN 1918-7173 E-ISSN 1918-7181 Published by Canadian Center of Science and Education 18 Psychological Skills Training Applied to Soccer: A Systematic Review Based on Research Methodologies Simão Freitas 1 , Claúdia Dias 1,2 & António Fonseca 1,2 1 Faculty of Sport, University of Porto, Portugal 2 Department of Sport Psychology, University of Porto, Portugal Correspondence: Simão Freitas, Faculty of Sport, University of Porto, Rua Dr. Plácido Costa, 91, Porto 4200-450, Portugal. E-mail: simao_11@hotmail.com Received: August 14, 2013 Accepted: September 13, 2013 Online Published: October 11, 2013 doi:10.5539/res.v5n5p18 URL: http://dx.doi.org/10.5539/res.v5n5p18 Abstract The purpose of this study was to provide a systematic review of studies on psychological skills training (PST) applied to soccer from 1980 until the end of 2012. A total of 28 studies were evaluated and reported in five sections: year overview and journals, research designs, data collection, sample characteristics and PST focus category. PST articles applied to soccer were spread throughout a wide range of journals and had a considerable growth during the 2008-12 period. Results also indicated that most of the research on PST applied to soccer was experimental, longitudinal and combined quantitative and qualitative data. Furthermore, the majority of studies focused on non-elite players with a age under 16 and were conducted in North American countries.Critical and innovative reflections were made in order to highlight potential research gaps and to suggest new perspectives for further investigation. Keywords: psychological skills training, soccer, research design, data collection, sample characteristics 1. Introduction Soccer is undoubtedly one of the most popular sports in the world, engaging people worldwide as players, spectators and TV viewers (Haugaasen & Jordet, 2012). A survey by the Fédération Internationale de Football Association (FIFA) in 2006 reported that 265 million people regularly play soccer (FIFA, 2007b), making soccer one of the most highly participated sports in the world. In addition, large soccer events have in recent years drawn more TV viewers than most other sporting events. The world cup tournament of 2006 had 27 billion accumulated viewers and the final alone attracted an audience of more than 700 million (FIFA, 2007a). For Joseph S. Blater, FIFA president, soccer popularity remains undiminished and is actually increasing (FIFA, 2007c). This global access to soccer requires an optimal performance from all of its practitioners, particularly, soccer players. In order to boost soccer players’ performance, researchers all over the world have actively studied these practitioners in different areas of sports sciences, including sport psychology. In this context, Psychological skills training (PST) research has emerged as an important tool to support the psychological preparation of soccer players in the accomplishment of higher performances (Thelwell, Greenlees, & Weston, 2006, 2010). The development of any profession relies on research, training programmes and innovations in practice (Gilbert & Trudel, 2004). A detailed analysis of the published research provides a resource for those conducting research in the area and for those reading the body of literature (Silverman & Skonie, 1997). In order to overcome the limitations of traditional reviews or narrative summaries, several authors (Littell, Corcoran, & Pillai, 2008; Noblit & Hare, 1988) had promoted the development of systematic methods (i.e., systematic reviews and meta-analysis). Craig et al., (2008) stressed the benefits of conducting systematic reviews in developing interventions and designing future studies. According to Craig et al., systematic reviews allow researchers to use the best available evidence and appropriate theories to develop future research directions and intervention strategies, as well as to raise awareness of the range of research methods employed in the study area. However, systematic reviews analyzing research methods employed in PST studies applied to soccer are clearly undeveloped. In fact, to our knowledge, no research was identified with this specific purpose. There are different ways to conduct research (i.e., experimental or descriptive; cross-sectional or longitudinal;