Relationships Between Internal and External Match-Load Indicators in Soccer Match Officials

Abstract

The aims of this study were to describe the internal and external match loads (ML) of refereeing activity during official soccer matches and to investigate the relationship among the methods of ML quantification across a competitive 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 (FRs) and 43 assistant referees (ARs) participated in the 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]) ML, external (total distance covered, distance covered at high speeds, and player load) ML, and ML differentiated ratings of perceived respiratory (sRPEres) and leg-muscle (sRPEmus) exertion. Internal and external ML were all greater for FRs than for ARs (–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). The authors found substantial differences between RPEres and RPEmus scores in both FRs (0.6 AU; ±90% confidence limits 0.4 AU) and ARs (0.4; ±0.3). These data demonstrate the multifaceted demands of soccer refereeing and thereby highlight the importance of monitoring both internal and external ML. Moreover, dRPE represents distinct dimensions of effort and may be useful in monitoring soccer referees’ ML during official matches.

The Relationships Between Internal and External Measures of Training Load and Intensity in Team Sports: A Meta-Analysis

“…This acute dose-response paradigm forms the basis of training theory [1] and is important for understanding the specific internal responses associated with various external training doses [19]. A knowledge of the relationships between internal and external training loads therefore has the potential to enhance training prescription, periodization and athlete management through a detailed assessment of training fidelity and efficacy [17,[19][20][21]. As an adjunct to this, internal-external load relationships can provide evidence for the construct validity and sensitivity of specific internal load indicators [22], which is important in absence of any 'gold-standard' criterion measure.…”

Understanding Player Load: Meanings and Limitations

“…Studies on sports training have used inertial sensors to measure the external load, which is the physical demand that is experienced by players during training or competition (Castillo et al, 2017) (e.g., distance covered, mean velocity, and accelerations; Schelling and Torres-Ronda, 2016;Weaving et al, 2017). A commonly used variable to describe the external load is Player Load (PL), which is a term that has been proposed by Catapult Sports, a company that provides sports technology.…”

“…Consequently, we observed possible difficulties in understanding the meanings that are attached to PL as a descriptor of the external load. The following examples, which have been extracted from different journal articles, illustrate the inconsistencies in the meanings that have been assigned to PL: "Player Load was computed as vector magnitude representing the sum of accelerations recorded in the anterior-posterior, mediolateral and vertical planes of movement" (Castillo et al, 2017).…”

External and internal training load relationships in soccer players

“…Dalen et al (2016) reported that DEC and ACC contributed to up to 10% of the total player load (PL) in soccer. Thus, calculating the number of ACC and DEC actions and PL using the sum of accelerations recorded in the three principal axes of movement (anteroposterior, mediolateral, and craniocaudal) are very common external load monitoring methods over recent decades (Boyd, Ball, & Aughey, 2013;Castillo, Weston, McLaren, Cámara, & Yanci, 2017;Scanlan, Wen, Tucker, Borges, et al, 2014;Soligard et al, 2016). Although accelerometers and GPS devices that enable ACC parameters to be measured have been used for individualization and optimization of exercise and recovery programs by coaches and sports scientists there are few studies in team sports which have made use of those values.…”