Table 1 Polar questions used to review literature

Sample type

 Was a complete season/tournament analysed?

 Was the research from a one-off tournament (example, World Cup)?

 Did the research include data from multiple seasons or tournaments?

 Were differentiations made between competition stages?

Operational definitions

 Were the variables analysed fully defined?

 Were the variables partially defined?

 Was reference made to a previous publication, or the development of definitions, but not provided in the article?

 Were definitions provided insufficient?

Match-related context

 Was the relative strength of the opposition considered in the analysis?

 Was there a reference made to the match location?

 Were environmental factors taken into account? (Weather, field condition)

Event-related context

 Was there a comparison between different outcomes?

 Was the playing position included in the analysis and differentiated in the results?

 Was the field position taken into consideration?

 Was there specific information relating to the playing situation of the assessed variables? (Formation or movement of the attacking and defensive lines, the number of support players, the type of pass/kick, etc.)

 Was technique assessed? (injury studies only)

Practical application

 Was there a reference to the practical application of the findings?