Investigating the impairment-performance relationship during competition in elite blind and partially sighted football.

Introduction: Classification systems aim to minimise the impact of impairment on competition outcome. To measure the effectiveness of a classification system, the relationship between impairment and performance must be investigated. There are two forms of football for athletes with vision impairment (VI): blind football and partially sighted football. Athletes are allocated to either one based on VI severity. Research is yet to assess the impact of impairment on performance in competition; therefore, this study aimed to measure the impairment-performance relationship in male blind, partially sighted and women's blind football. Methods: Notational data consisting of several technical performance measures were assessed (including, but not limited to, possession, passing, shots, and goals) and combined with visual function data from elite blind and partially sighted footballers. Correlations of notational match data and visual acuity (VA) were measured for male blind and partially sighted footballers (study one) and women's blind footballers (study two). Results: In study 1: the team-level analysis revealed a weak but statistically significant correlation between win ratio and VA for male blind football (r = 0.227). The player-level analysis revealed that VA was correlated with defensive zone clearances (r = 0.198), shots on target (r = 0.237), and shots saved (r = 0.229). In partially sighted football, team-level analysis revealed that VA was significantly correlated with win ratio (r = -0.534) and ball possession (r = 0.419). The player-level analysis revealed that VA was correlated with the number of fouls committed (r = 0.273) and fouls won (r = -0.273). These findings suggest that impairment may impact the outcome of competition in male blind and partially sighted football. In study two, win ratio was not correlated with VA (r = -0.095) in women's blind football, implying that impairment does not impact competition outcome and that fairness may be achieved. Discussion: These results evidence a different impairment-performance relationship for each version of the sport, and that the current classification system may not optimise fairness across each form of football.