Individual-Specific Relationship Between External Training and Match Load and Creatine-Kinase Response in Youth National Team Soccer Players

Abstract

Background: Previous studies have examined the relationship between external load and creatine-kinase (CK) response at the team level. This study aimed to build individualized CK prediction models for elite youth national team soccer players. Hypothesis: The CK response of youth soccer players can be categorized as being sensitive to micromovements (MM), high-velocity (HV) parameters, or the combination of both, measured during training sessions and matches. Study Design: Prospective cohort study. Level of Evidence: Level 4. Methods: A total of 25 U16-U17 youth national team soccer players were monitored during training sessions and matches using global positioning system (GPS) units. Individual CK values were measured every morning from whole blood. The data set consisted of 57 ± 17 individual datapoints per player. Individual prediction models were used to examine the relationship between external load and consecutive CK changes. Numerous models were built for each player using MM, HV parameters, or the combination of both. The performance of the models was described by the R2 and the root mean square error (RMSE, U/l for CK values). Results: The MM models were superior for 8 players ( R2 = 0.68; RMSE = 113 U/l), followed by HV (8 players; R2 = 0.69; RMSE = 88 U/l) and the combined models (2 players; R2 = 0.64; RMSE = 141 U/l). For the remaining 7 players, the R2 of the models was <0.5. The recovery time between efforts was more important in the HV model. Conclusion: Players could be categorized on sensitivity to MM, HV movements, or the combination of both. Clinical Relevance: These findings can be used to individualize postmatch recovery strategies and to optimize weekly training periodization to maximize match performance.

Biomarkers of post-match recovery in semi-professional and professional football (soccer)

“…While this approach shows promise for monitoring individual CK values in athletes, it may not be intuitive for professionals to implement, and the requirement for prior individualized values can present a challenge. Lastly, based on previous research focused on associations between external load metrics and CK values at team level ( Hader et al, 2019 ; Wiig et al, 2019 ), models aimed to predict individualized CK values have been recently reported ( Schuth et al, 2022 ). Identifying which load parameters best correlate this marker is important ( Schuth et al, 2022 ).…”

“…Lastly, based on previous research focused on associations between external load metrics and CK values at team level ( Hader et al, 2019 ; Wiig et al, 2019 ), models aimed to predict individualized CK values have been recently reported ( Schuth et al, 2022 ). Identifying which load parameters best correlate this marker is important ( Schuth et al, 2022 ).…”

Tracking devices and physical performance analysis in team sports: a comprehensive framework for research—trends and future directions

“…In addition, an understanding of load dynamics across training and competition is presented as an important aspect related to performance enhancement in team sports (8,47,60,61), showing, for example, how adjusting specific drills such as large,-medium-and small-sided games may help replicate game demands (86,87). Correlations between EL and IL in different season periods were applied in order to understand the fluctuation of some metrics such as players' strength (88), players' recovery (89), or ACWR, between players' positions, starters, and non-starters (82, 84,90,91). Also, Pizarro et al (26) demonstrated how different occupational areas may promote different physical variables.…”

“…More recently, performance analysis research is stepping forward on the understanding of HIAs and on predictive studies for fatigue and match performance. The literature suggests that during different phases of a training cycle, such as the baseline or competition phase, training loads must be modulated to either enhance or reduce fatigue levels (89). In the light of this, it is important to understand the match HIA in order to manage fatigue properly, matching both variables to adaptation to training and for achieving competitive performance (10,40).…”

“…In the light of this, it is important to understand the match HIA in order to manage fatigue properly, matching both variables to adaptation to training and for achieving competitive performance (10,40). On the other hand, understanding HIAs and their impacts on IL also improves the knowledge of individual players' recovery strategies (89). The importance of understanding effort categories (moderate and hard) has already been established in a systematic review, in which agreements between coaches and athletes about total RPE and s_RPE were reported (13).…”