Relationship between Repeated Sprint Ability, Countermovement Jump and Thermography in Elite Football Players.

Football is a very demanding sport which requires players to exert maximum effort, producing fatigue and eventually injuries. Thermography can be used to detect fatigue and prevent its consequences through thermal asymmetries in the bilateral body areas; however, its adequacy for elite footballers has not been widely studied. Therefore, the objective of the present investigation was to determine the suitability of thermography to detect fatigue in male football players. For this reason, twenty participants were gathered into a pair of subgroups (low [<0.2 °C] vs. high thermal asymmetry [≥0.2 °C]) based on a thermography session of the lower limbs (thighs, calves, and hamstrings). After the thermography session, players performed CMJs before and after an RSA test (6 × 30 m/20″). A mixed two-way analysis of variance and Bonferroni post hoc pairwise comparisons were undertaken to analyse the results. No significant differences (p > 0.05) were found in any of the RSA test variables between low and high thermal asymmetry groups for thighs and calves. On the other hand, the low thermal asymmetry hamstring group reported a smaller percentage difference in sprints for the first sprint (%Diff) and a larger percentage difference in sprints two and three with respect to the best sprint (%Best). For CMJs, the low thermal asymmetry hamstring group reported significantly higher values post-RSA test, indicating better performance. Accordingly, thermography can provide information about performance in CMJ and RSA tests through hamstring asymmetries over 0.2 °C. Meanwhile, larger asymmetries than 0.2 °C in calves and thighs do not seem to be related to performance in these tests; therefore, coaches should consider if it is optimal to align players with high hamstring asymmetries.

Differences in body composition and physical fitness parameters among prepubertal and pubertal children engaged in extracurricular sports: the active health study.

BACKGROUND: This study aimed to analyze the associations of maturity status, chronological age and sex with physical fitness and body composition among active children. METHODS: A total of 1682 children (72% boys; age = 11.22 ± 2.64 years; height = 147.57 ± 15.87 cm; weight = 44.55 ± 15.29 kg) from rural areas participating in extracurricular sports were divided into four groups according to their sex and maturity status (prepubertal and pubertal according to stages described by Tanner). Body composition (body mass index, muscle mass and fat mass) and physical fitness (20-m shuttle-run test, handgrip strength and vertical jump) were assessed using standardized procedures. A two-way ANOVA and product-moment correlations were performed. RESULTS: Prepubertal boys had more fat mass (%) than pubertal boys [P<0.001; effect size (ES): 0.45], while prepubertal girls had more muscle mass (%) than pubertal girls (P<0.001; ES: 0.47). The pubertal group displayed higher fitness outcomes (absolute values) regardless of sex (P<0.05). However, the prepubertal group had higher percentile values in the 20-m shuttle-run test and vertical jumps than the pubertal group regardless of sex (P < 0.001; ES: 0.29-0.48). All the measures of physical fitness were positively associated with chronological age and muscle mass (%). CONCLUSIONS: Although absolute values of body composition and physical fitness appear to increase among pubertal children participating in extracurricular sports, the percentiles indicate that puberty is accompanied with a loss of a physical fitness levels. Thus, extracurricular sports might not be enough to enhance fitness among adolescents.

Physical Demands during the Game and Compensatory Training Session (MD + 1) in Elite Football Players Using Global Positioning System Device.

The aims of this study were to analyze the differences of physical demands of non-starter players regarding the playing time during the competition and to evaluate the physical demands of the compensatory training (MD + 1C) for substitute players in elite football. The match statistics and MD + 1C of substitute players from a professional Spanish LaLiga football club were analyzed using a 10-Hz global positioning system (GPS) Apex GPS system device, which has been validated as a reliable and valid method to analyze performance in team sports, during all games of the 2016/2017, 2017/2018 and 2018/2019 seasons. The starting players showed both lower total distances covered and high-intensity actions compared to the substitutes. Regarding the minutes played by the substitutes, greater physical performance was found for the players with fewer minutes (5−15 min). Furthermore, no differences were found between first and second divisions regarding physical performance of substitutes (p > 0.05). This study highlights the importance of individualizing the workload of training sessions for substitutes and starters. Furthermore, the complementary session should be individualized according to the minutes played by the substitutes. These players are potentially under-loaded compared to starters, especially in terms of high-intensity actions, therefore additional session-specific training for each substitute would be useful to reach the optimal training load according to the minutes played during the game.

The Effects of Football Practice on Nutritional Status and Body Composition in Children: A Systematic Review and Meta-Analysis.

Dietary patterns, exercise, sport, and physical activity have been shown to improve body composition in children. This systematic review with meta-analysis analyzed the effects of practicing football on body composition (fat mass, lean body mass, and bone mineral content) in children. An initial search in PubMed, Web of Science, and SPORTDiscus was carried out in April 2021 to identify relevant articles. Inclusion criteria required children up to 12 years of age with a minimum football intervention duration of 10 weeks. Methodological quality of the articles was evaluated using the PEDro scale. Between the 1803 articles originally founded, only 14 articles were included in the meta-analysis. A total of 1643 subjects between the 14 studies were identified. The review and meta-analysis were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and used Review Manager and Full Meta-Analysis software. The results between the control and experimental groups showed significantly better lean body mass and fat mass values in the experimental group (p < 0.05). Football practice was positively associated with increases in lean body mass (mean difference of 1.55; 95% CI, 0.96, 2.15), decreases in fat mass (mean difference of -0.81; 95% CI, -1.49, -0.13), and increases in whole body bone mineral content (mean difference of 117.68; 95% CI, 83.69, 151.67). In conclusion, the results of this systematic review with meta-analysis suggest that football positively affects body composition in children. However, further research is needed to confirm the results for bone mineral content.

Influence of the artificial turf certification on physical performance and muscle damage in football players (QUALTURF PROJECT).

This study aimed to analyse the influence of the FIFA Quality PRO certification of artificial turf pitches on the physical, physiological performance and muscle damage in soccer players. Fifteen healthy male players (21.2 ± 1.4 years; 178.2 ± 4.3 cm; 79.1 ± 8.3 kg) from a university football team were selected to participate in the research. Mechanical properties related to surface-player interaction were assessed on the two surfaces selected for this study. A randomized design was used and the players performed the Ball-sport Endurance and Sprint Test (BEAST90) on the different artificial turf fields. Average time of the 20 m sprints was longer on the FIFA Quality Pro surface than on the non-certified pitch (+ 0.13 s; p < 0.05; CI 95% - 0.01 to 0.27; ES: 0.305). The players' perceived effort was higher in the first (+ 2.64; p < 0.05; CI 95% 0.92 to 4.35; ES: 1.421) and the second half (+ 1.35; p < 0.05; CI 95% - 0.02 to 2.72; ES: 0.637) of the test on the FIFA Quality Pro field. Comparative analysis between surfaces showed no significant differences in the time spent in each of the heart rate zones and higher concentrations of CK (+ 196.58; p > 0.05; CI 95% 66.54 to 326.61; ES: 1.645) were evidenced in the non-certified pitch surface. In response to a simulated match protocol, markers of post-exercise muscle damage may be reduced on accredited artificial turf fields. These insights can provide the opportunity to maximize the efficiency of training sessions and reduce the risk of injury during the season.

Effect of Natural Turf, Artificial Turf, and Sand Surfaces on Sprint Performance. A Systematic Review and Meta-Analysis.

The aim of this study was to analyze the influence of natural turf, artificial turf, and sand on sprint performance in different sports and to determine how the sport surface affects sprint performance. A systematic search was conducted in Pubmed, Web of Sciences, and SPORTDiscus databases. Out of 5644 studies, 11 studies were included in the meta-analysis. The studies were very heterogeneous, as they examined different structural characteristics or quality parameters. The studies on natural turf and sand showed significant improvements on sprint speed during training. On the other hand, the analysis of fatigue did not reveal significant differences in the deterioration of sprint speed on both natural and artificial turf. Significance was set at p < 0.05. In conclusion, although lower performance in sprint was reported on sand, further studies are needed to explain the differences in sprint on natural and artificial turf.

Physical Demands of U10 Players in a 7-a-Side Soccer Tournament Depending on the Playing Position and Level of Opponents in Consecutive Matches Using Global Positioning Systems (GPS).

The aim of this study was to analyse the physical demands of U10 players in a 7-a-side-soccer tournament based on the playing positions in 6 consecutive matches by global positioning systems (GPS). Variables of total distance, relative distance in different speed zones, maximum speed, time interval between accelerations, maximum speed acceleration, maximum acceleration, acceleration distance and the number of high-intensity accelerations were analysed. Differences between playing positions were found in the total distance covered by the midfielders. They covered higher total distances than the defenders (+1167 m; 95% CI: 411 to 1922 m; effect size (ES) = 1.41; p < 0.05) and forwards (+1388 m; CI 95%: 712 a 2063 m; TE = 0.85; p < 0.05). The total covered distance increased in the final rounds with respect to the group stage (p < 0.05; ES: 0.44 to 1.62), and high-intensity actions, such as the number of accelerations, were greater in the final rounds compared to the group stage (p < 0.05; ES: 0.44 to 1.62). The physical performance of young football players in a tournament with consecutive matches on a 40 × 62 m football field on the same day is influenced by the playing position and dependent on the level difference between opponents.

Weight Status, Adherence to the Mediterranean Diet, and Physical Fitness in Spanish Children and Adolescents: The Active Health Study.

The aim of this study was to analyze the differences in body composition and physical fitness according to the weight status (normoweight, overweight and obese) and the level of adherence to the Mediterranean diet (MD; low, medium or high), in physically active children and adolescents. Furthermore, this study also analyzed the relationship between body composition and physical fitness with Body Mass Index (BMI), fat mass and the level of adherence to the MD. In total, 1676 participants aged 6-17 from different municipal sports schools participated in this cross-sectional study. Data on adherence to the MD (a KIDMED questionnaire), anthropometric measurements, body composition and physical fitness parameters (the 20-m shuttle run test and muscular strength) were collected. A total of 43.5% of the sample were presented as overweight and obese, and only 35.7% had high or optimal adherence to the MD. The results revealed that a normoweight status was associated with greater cardiorespiratory fitness (p < 0.05; ES: 0.50 to 0.67) and lower-body muscular strength (p < 0.05; ES: 0.58 to 1.10). The overweight group showed more significant results than the other groups in handgrip strength (p < 0.01). Greater adherence to the MD in this population indicated better physical fitness, but only in boys. It is concluded that normoweight status and optimal adherence to the MD in children and adolescents are associated with health benefits, which are significant in the body composition and the effect on physical fitness.

Relationship between Adherence to the Mediterranean Diet and Body Composition with Physical Fitness Parameters in a Young Active Population.

The current study aimed at analyzing the relationship between body composition, adherence to the Mediterranean diet (MD), and physical fitness (PF) in a young active population. A total of 1198 athletes (boys = 875; girls = 323) enrolled in different municipal sports schools participated in this study. Data on adherence to the MD (KIDMED questionnaire), anthropometric measurements, and PF (20 m shuttle run test, handgrip strength, vertical jump and forced spirometry) were collected. Results show that the pubertal boys had a higher score in the KIDMED test than the prepubertal ones (+0.38, p = 0.28). Moreover, boys with better adherence to the MD had significantly higher results in handgrip strength (+12.20 regarding low MD group and +9.13 regarding medium MD group, p < 0.05), as well as in forced vital capacity (FVC) (+0.66 regarding low MD group and 0.29 regarding medium MD group, p < 0.05). No differences were found in the girls. Finally, the result of the KIDMED test is a variable with a positive and significant relationship with cardiorespiratory fitness, along with the FVC, percentage of fat mass, and performance in the vertical jump (p < 0.05). It is concluded that adherence to the MD could show a relationship with various PF variables in boys and could be a predictor of cardiorespiratory fitness in both cases.

Physical Fitness, Body Composition, and Adherence to the Mediterranean Diet in Young Football Players: Influence of the 20 mSRT Score and Maturational Stage.

This study aimed to analyze the differences in physical fitness variables, body composition, and adherence to the Mediterranean diet according to the cardiorespiratory fitness and the maturational stage in young football players. A total of 194 male football players (aged 8-16) from three football sport schools participated in this study. Data on cardiorespiratory fitness (the 20-m shuttle run test), anthropometric measurements, handgrip strength, respiratory capacity (forced spirometry), and adherence to the Mediterranean diet (KIDMED questionnaire) were collected. Players were divided into two groups depending on their maturational stage (prepubertal n = 127 and pubertal n = 67). The results show a direct relationship between low levels of cardiorespiratory fitness and body mass index, as well as body fat and leg fat. Similarly, players with lower cardiorespiratory fitness presented higher values of handgrip strength in the prepubertal state. On the other hand, improvements in respiratory values were observed in the pubertal state with the rest of the parameters when the cardiorespiratory fitness was increased. Therefore, the promotion of recreational football that encourage and develop cardiorespiratory fitness is a key factor and can be used as an effective sport activity to promote physical fitness and healthy habits in children and adolescents as well as within the population that is already physically active.

Comparison between Two Different Device Models 18 Hz GPS Used for Time-Motion Analyses in Ecological Testing of Football.

BACKGROUND: The aim of this study was to compare the validity of two different GPS device models used for time-motion analyses in ecological testing of football. METHODS: Ten healthy male players from a Spanish university football team participated in this study. The team sport simulation circuit (TSCC) used was based on previous research examining the validity and interunit reliability of different GPS systems. Participants were required to complete eight laps of the TSSC, resulting in a total distance of 1320 m. The GPS units used for the current study were the 18 Hz StatsSport Apex Pro and 18 Hz RealTrack WIMU Pro. Participants were required to wear either of the two GPS units during the test. To establish the construct validity of GPS as a measure of Vmax, timing lights were used as a gold standard. RESULTS: The results clearly suggest that it is not possible to use the same 18 Hz GPS model or interchange it. The measurement can be considered precise when the noise is at least equal to or lower than the smallest worthwhile change. In this case, all standard deviation in measurement error was higher than the smallest worthwhile change. This is due to an inconsistency in the data processing of each trademark. CONCLUSIONS: It is important to prevent a club using different GPS trademarks at the same time, since it is not possible to compare in any case any type of result obtained between different trademarks.