Characterising the Internal and External Load During Warm-Up, Match Play and Training in Soccer Substitutes: A...

Shorter match-play exposure for soccer substitutes relative to those who start matches has implications in the days before, during and following match play concerning their training, preparatory and recovery/compensatory practices. Specifically, characterising the internal and external loading of substitute players throughout a weekly microcycle can facilitate evidence-based recommendations aimed at optimising their performance readiness.

This systematic scoping review aimed to map and characterise the internal and external loading associated with warm-up, match play and training in soccer substitutes.

Prior to literature searches being conducted, a Population, Intervention, Comparison, Outcome, Study design (PICOS) statement was formed. Online database (PubMed, SPORTDiscus, Scopus and Web of Science) searches were performed according to PRISMA Extension for Scoping Reviews (PRISMA-ScR) protocols. Studies were eligible if internal or external characteristics of soccer substitutes were measured in training or match-play scenarios. After calibration exercises, two authors independently quality assessed each study, with Cohen's kappa undertaken to assess inter-rater agreement. A scoping review methodology was selected because of the methodological and conceptual heterogeneity across studies, which precluded meaningful meta-analysis.

A total of 5135 studies were identified, 66 of which met study criteria. Substantive inter-rater agreement was observed (κ = 0.939, p < 0.001) during the quality assessment of included studies. Soccer substitutes' body temperature, and thus several aspects of physical performance, may not be maintained at time of pitch entry (body temperature pre-pitch entry ~ 37 °C vs match play > 38 °C). Substitutes may experience lower absolute physical loading during training and match day (e.g. match-day 'top up' activity: ~ 17 min; total distance: ~ 1700 m) but during match play, substitutes typically cover higher relative total distances (~ 109 to ~ 137 m·min^-1), high-speed running (~ 9.8  to ~ 13.5 m·min^-1) and sprinting distance (~ 3.8 to 5.0 m·min^-1) compared with players who started the match. Substitutes playing in the second-half exhibit increased heart rates compared with full-match players (84% vs 81% maximum heart rate); however, this remains lower than the first-half heart rate responses of full-match players (84% vs 86% maximum heart rate).

This systematic scoping review summarises current evidence and key findings relating to the internal and external characteristics of soccer substitutes during warm-up, match play and training that can be used in practice to inform player welfare and sport science support within these cohorts. Chiefly, during match-day warm-ups, soccer substitutes' body temperature and physical performance responses may not be maintained, despite typical substitute-specific match-day practices being employed. Similarly, soccer substitutes were frequently reported to demonstrate higher relative total distance, high-speed running and sprinting outputs compared with starting players. Further research is needed to better understand performance demands, longitudinal adaptations, contextual influences and female-specific responses in soccer substitutes.