RESUMEN
BACKGROUND: Team management, especially player selection, rotation, and availability, are critical issues when dealing with the high demands of modern training and gameplay. As such, research continuously seeks ways to improve these actions or implement new ideas to gain a competitive advantage through the rotation of players in the starting line-up. The current study aimed to examine the rounds of the 2018 FIFA World Cup Russia in which the most rotations of key players were made and how this affected physical activity. METHODS: The sample consisted of 110 players from the top eight teams in the 2018 World Cup Russia who played entire matches for up to 90 min in seven consecutive games. All players were divided into key players (KPs, n = 58) and non-key players (NKPs, n = 52). The analysis used data collected by an advanced motion analysis system known as STATS®, with physical activity variables analyzed, including total distance covered (TDC), distance covered with high intensity over 20 km/h (HIR), and the number of sprints undertaken. In statistical analysis, differences between categories and consecutive matches were calculated using the Kruskal-Wallis H test, and if a significant effect size was found, a multiple comparisons p values test was performed. RESULTS: The best teams at the 2018 FIFA World Cup Russia used the most KP rotations with NKPs in the third match of the group stage. In addition, this was even more visible among more successful teams than less successful teams. The rotation strategy among the best eight teams allowed them to maintain the physical activity of KPs and NKPs in all rounds of the tournament. CONCLUSIONS: Coaches and coaching staff should incorporate squad rotation that includes a large group of players in their team management to improve their success. Team management expertise in player rotation during matches played over congested schedules at top tournaments maintains high levels of physical activity indicators (TDC, HIR, and sprints).
RESUMEN
This study aimed to investigate the effects of a 4-week specific high-intensity interval training (HIIT) program performed between the anaerobic threshold (ANT) and the psychomotor fatigue threshold (PFT) on physiological parameters in 14 professional soccer players at the under-17 level. The first and second stages of the research protocol included a treadmill running exercise with increasing load and six 3-min four-versus-four games of soccer with a 3-min break between games. Players then participated in a training microcycle involving three specific HIIT exercises twice per week for 4 weeks, after which they repeated stages one and two, followed by an assessment of changes. The measurement of lactate (LA) determined ANT, whereas the choice reaction time (CRT) indicated PFT among other selected physiological parameters. The repeated-measure analysis of variance (ANOVA) compared mean values for the examined variables using Bonferroni post hoc test. It demonstrated significantly increased maximal oxygen consumption (VO2 max) from 45.9 ± 3.0 to 48.7 ± 2.6 at the ANT and from 49.1 ± 3.4 to 52.0 ± 3.6 on the PFT after 4 weeks of training. A significant increase in the running speed (RS) at both thresholds and heart rate (HR) at the ANT (p ≤ 0.05) was also recorded. Moreover, the players exceeded their intensity of effort during ANT while playing four-versus-four soccer matches, but they did not reach intensity during PFT. In conclusion, the findings of the study demonstrated that both thresholds shifted toward higher loads and the proposed specific HIIT effectively increased the exercise capacity of soccer players.
RESUMEN
This study aimed to investigate the relationship between the climatic conditions predicted for the 2022 FIFA World Cup in Qatar and the capacity for repeated maximum effort (RSA), of soccer players. Twenty-four semi-professional soccer players participated in the study. The exercise test consisted of ten 6-second maximal efforts on a cycloergometer. A 90-second passive rest interval was used. Mechanical parameters were recorded in each repetition, and biochemical parameters at rest and even repetitions. The test was performed in a Weiss Technik WK-26 climate chamber under two different conditions: (1) thermoneutral (TNC - 20.5 °C; 58.7% humidity); (2) predicted for the 2022 World Cup in Qatar (QSC - 28.5 ± 1.92 °C; 58.7 ± 8.64% humidity). Significantly higher mean maximum power values were recorded in the second repetition under QSC conditions (1731,8 ± 214,4 W) (p = 0.025). A significantly longer time to reach maximum power was also recorded under TNC conditions compared to QSC conditions in repetition 2 (1,32 ± 0,33 s), (1,05 ± 0,29 s) (p = 0.016) and 6 (1,41 ± 0,48 s), (1,17 ± 0,25) (p = 0.036). There was a significantly higher rate of power loss, between repetition 2 (p = 0.023) and 4 (p = 0.043) under QSC conditions, compared to TNC. Considering the biochemical parameters, a significantly higher pO2 concentration was registered under QSC conditions in the 10th repetition (p = 0.006). The ambient temperature during exercise should be taken into account to determine the anaerobic exercise capacity of the athletes. At higher temperatures, there is a greater capacity for maximal effort, in terms of maximal power achieved, but with a greater decrease in performance.