Relationships between internal and external match load indicators in soccer match officials

The aims of this study were to describe the internal and external match load (ML) of refereeing activity during official matches and also to investigate the relationship among the methods of ML quantification across a competitive soccer season. A further aim was to examine the usefulness of differential perceived exertion (dRPE) as a tool for monitoring internal ML in soccer referees. Twenty field referees (FR) and 43 assistant referees (AR) participated in this study. Data were collected from 30 competitive matches (FR = 20 observations, AR = 43 observations) and included measures of internal (Edwards’ heart rate derived training impulse [TRIMPEDW]), external (total distance covered [TD], distance covered at high speeds [HSR] and player load [PL]) ML, differentiated ratings of perceived respiratory [sRPEres ML] and leg muscle [sRPEmus ML] exertion). Internal and external ML were all greater for FR when compared to AR (-19.7 to -72.5); with differences ranging from very likely very large to most likely extremely large. The relationships between internal ML and external ML indicators were, in most cases, unclear for FR (r < .35) and small to moderate for AR (r < .40). We found substantial differences between RPEres and RPEmus scores in both FR (.6 AU; ±90% confidence limits .4 AU) and AR (.4; ±.3 AU). These data demonstrate the multifaceted demands of soccer refereeing and thereby highlight the importance of monitoring both internal and external ML. Moreover, dRPE represent distinct dimensions of effort and may be useful in monitoring soccer referees ML during official matches.