High coenzyme Q10 plasma levels improve stress and damage markers in professional soccer players during competition.

Ubiquinol, the reduced form of Coenzyme Q10 (CoQ10), is a key factor in bioenergetics and antioxidant protection. During competition, professional soccer players suffer from considerable physical stress causing high risk of muscle damage. For athletes, supplementation with several antioxidants, including CoQ10, is widely recommended to avoid oxidative stress and muscle damage. We performed an observational study of plasma parameters associated with CoQ10 levels in professional soccer players of the Spanish First League team Athletic Club de Bilbao over two consecutive seasons (n = 24-25) in order determine their relationship with damage, stress and performance during competition. We analyzed three different moments of the competition: preterm, initial phase and mid phase. Metabolites and factors related with stress (testosterone/cortisol) and muscle damage (creatine kinase) were determined. Physical activity during matches was analyzed over the 2015/16 season in those players participating in complete matches. In the mid phase of competition, CoQ10 levels were higher in 2015/16 (906.8 ± 307.9 vs. 584.3 ± 196.3 pmol/mL, p = 0.0006) High levels of CoQ10 in the hardest phase of competition were associated with a reduction in the levels of the muscle-damage marker creatine kinase (Pearsons' correlation coefficient (r) = - 0.460, p = 0.00168) and a trend for the stress marker cortisol (r = -0.252, p = 0.150). Plasma ubiquinol was also associated with better kidney function (r = -0.287, p = 0.0443 for uric acid). Furthermore, high CoQ10 levels were associated with higher muscle performance during matches. Our results suggest that high levels of plasma CoQ10 can prevent muscle damage, improve kidney function and are associated with higher performance in professional soccer players during competition.

Relationship between the relative age effect and anthropometry, maturity and performance in young soccer players.

The presence of the relative age effect (RAE) has been widely reported; however, its underlying causes have not yet been determined. With this in mind, the present study examined if anthropometry and performance were different amongst older and younger soccer players born in the same year. Eighty-eight young soccer players participated in the study (age 9.75 ± 0.30). Anthropometric measurements, physical tests (sprint, agility, endurance test, jump and hand dynamometry) and the estimation of the maturity status were carried out. Most players (65.9%) were born in the first half of the year. Older players were taller (P < 0.05), had longer legs (P < 0.01) and a larger fat-free mass (P < 0.05). Maturity offset was smaller in the older boys (P < 0.05); however, age at peak height velocity was similar. Older boys performed better in velocity and agility (P < 0.05) and particularly in the overall score of performance (P < 0.01). Stepwise regression analysis revealed that chronological age was the most important variable in the agility test and the overall score, after the skinfolds (negative effect). We report differences in anthropometry and physical performance amongst older and younger pre-pubertal soccer players. These differences may underlie the RAE.

Talent identification and selection process of outfield players and goalkeepers in a professional soccer club.

Abstract The aim of this study was to analyse the talent identification process of a professional soccer club. A preselection of players (n = 64) aged 9-10 years and a final selection (n = 21) were performed by the technical staff through the observation during training sessions and matches. Also, 34 age-matched players of an open soccer camp (CampP) acted as controls. All participants underwent anthropometric, maturity and performance measurements. Preselected outfield players (OFs) were older and leaner than CampP (P < 0.05). Besides, they performed better in velocity, agility, endurance and jump tests (P < 0.05). A discriminant analysis showed that velocity and agility were the most important parameters. Finally, selected OFs were older and displayed better agility and endurance compared to the nonselected OFs (P < 0.05). Goalkeepers (GKs) were taller and heavier and had more body fat than OFs; also, they performed worse in the physical tests (P < 0.05). Finally, selected GKs were older and taller, had a higher predicted height and advanced maturity and performed better in the handgrip (dynamometry) and jump tests (P < 0.05). Thus, the technical staff selected OFs with a particular anthropometry and best performance, particularly agility and endurance, while GKs had a different profile. Moreover, chronological age had an important role in the whole selection process.

Physical growth and changes in intermittent endurance run performance in young male Basque soccer players.

The present 4-year longitudinal study examined physical growth and development of intermittent endurance run performance in young Basque soccer players aged 10-15 years applying multilevel regression modeling. Anthropometry, predicted adult stature and Yo-Yo Intermittent Recovery level 1 test (Yo-Yo IR1) of players from the under-11 teams from the Athletic Club of Bilbao were measured at pre- and end-season (two measurements per year of study, n = 33 considered for analysis). A non-linear effect of age on intermittent endurance run was observed, with significantly higher increases in Yo-Yo IR1 between 10-11 year-old and 14-15 year-old players. The development of Yo-Yo IR1 performance in all the years of the study was influenced positively by training exposure during the seasons (P < 0.01) and independent of maturity status and body size (P > 0.05). The steady development of intermittent endurance run performance during pubertal years in adolescent Basque soccer players is partially influenced by training exposure.

Metabolic impact of a soccer match on female players.

The aim of this study was to examine the metabolic effect of a female soccer match in elite and sub-elite teams. Blood samples were taken (24 h before, immediately after and 18 h after official soccer matches) to determine haematological, electrolytic and hormonal variables, as well as the levels of cell damage and oxidative stress in 14 elite and 14 sub-elite players. Our results show increases in white blood cell count (P < 0.001) and the percentage of neutrophils (P < 0.001), and decreases in the percentage of lymphocytes (P < 0.05), eosinophils (P < 0.001), monocytes (P < 0.001) and basophils (P < 0.05) immediately post-match. Increases were also found in lactate dehydrogenase activity (P < 0.001), uric acid (P < 0.001), albumin (P < 0.001), total antioxidant status (P < 0.001) and free testosterone levels (P < 0.01). Creatine kinase activity significantly increased 18 h post-match (P < 0.01) and the concentrations of several ions, glucose and proteins were found to be altered immediately post-match. Overall, our results show that playing a soccer match exerts specific metabolic effects on female players, resulting in muscle damage, oxidative stress and biochemical and hormonal variations. On the basis of some interesting correlations, we also suggest that exercise-induced cell breakdown may enhance antioxidant capacity of the soccer players.

Anthropometry and performance of top youth international male basketball players in Spanish national academy.

The "Century XXI" Project is a seven-year intervention sport program performed among the best Spanish youth basketball players, who were assigned to one of the following intervention groups based on the following criteria: age, position, mature level, and origin in the country. The study was performed (1996-2001) with a total of 90 players. The main purposes of this study were: a) to describe anthropometric and performance characteristics of top youth international male basketballers in the Spanish national academy; and b) to analyze differences among positions. Insummary, the main findings of this study were: a) the anthropometry presented significant differences between groups under (U-) 14 and U-17; and b) in the U-17 group centers presented more arm span. In our study, the most significant changes are in U-16 vs U-14 and U-15 in strength body up values, and the best result in endurance capacity took place in June of the fourth year. Within this context, the results of the present study may be useful for strength and conditioning coaches to plan their programs with youth basketball players.

The Spanish "Century XXI" academy for developing elite level basketballers: design, monitoring and training methodologies.

OBJECTIVES: The XXI Century Academy was a 6-year state-initiated intervention program that served as an alternative to basketball clubs for players in the u-14 and u-18 age groups in Spain, under guidelines established by the Spanish Basketball Federation. It was an important and unique project on talent development in basketball. To the best of the authors' knowledge, no evidence has been reported on long-term athlete development programs in basketball worldwide. The main aim of this report is to describe the design and evaluation methods used for the XXI Century Academy as a long-term intervention program in the elite Spanish Basketball Academy, aiming to prepare basketball players to compete at the elite level. METHODS: The monitoring time lasted from 1996 to 2001. A total of 55 players were assigned to the intervention groups based on age, position, maturation level, and country of origin. During this process, participants competed in up to two categories in addition to playing competitive official matches worldwide in international tournaments in their categories and with the national team in the European and World Championships (u-14 - u-18). Participants included 1 NBA player, 3 national A Team players, 10 ACB (First Spanish League) players, 5 LEB (second League) players and 39 LEB-2 EBA (third League) players. Assessments took place in a High-Performance Sports Center (CPT FADURA-GETXO- Basque Government, Getxo, Vizcaya, Spain) and consisted of health questionnaires, anthropometric measures, blood parameters, maturation level, birth age, fitness tests, training volume and intensity, physical activity, technical and tactical training, dietary intake, supplementation and injuries. Each player was assessed 4 times per year (September, December, April, June) for 4 years (16 data points). RESULTS: This is a purely methodological paper describing the design and evaluation methods used in the XXI Century Project, which will be used as a basis for future reporting of results. Therefore, the results of the project will be reported in subsequent publications. CONCLUSION: The viability of the Century XXI Project protocols has been described. This national project of training in basketball closely replicates the physical and technical match-play conditions for professionals and may constitute a useful training tool.

Hematological changes in an elite climber over 18 years.

AIMS: To evaluate the influence of repeated exposure to high altitude over a period of 18 years in an elite climber, red blood cell related parameters were analyzed. Red blood cell levels, hemoglobin concentration, and hematocrit were taken before and after expedition. RESULTS: The analysis, revealed an average increase of 15% in red blood cell related parameters, and showed a negative correlation (p<0.01) between age and post-expedition results. Furthermore, the first part of the study period was statistically different compared to the second (p<0.01). CONCLUSION: Exposure to extreme altitudes does lead to an increase in red blood cell parameters in the subject of the present study, as it can be seen from the results. Interestingly, this hematological response to extreme hypobaric hypoxia stimuli was attenuated over time. This however is a case report on an elite climber, and further research is needed in order to determine if such responses can be observed in other populations.

Influence of nutrient intake on antioxidant capacity, muscle damage and white blood cell count in female soccer players.

BACKGROUND: Soccer is a form of exercise that induces inflammatory response, as well as an increase in free radicals potentially leading to muscle injury. Balanced nutritional intake provides important antioxidant vitamins, including vitamins A, C and E, which may assist in preventing exercise-related muscle damage. The purpose of the present study was to determine the effect of macro/micronutrient intake on markers of oxidative stress, muscle damage, inflammatory and immune response in female soccer players. METHODS: Twenty-eight female players belonging to two soccer teams of the same professional soccer club participated in this study after being informed about the aims and procedures and after delivering written consent. Each team completed an 8-day dietary record and played one competition match the same week. Participants were divided into two groups: the REC group (who complied with recommended intakes) and the NO-REC group (who were not compliant). Laboratory blood tests were carried out to determine hematological, electrolytic and hormonal variables, as well as to monitor markers of cell damage and oxidative stress. Blood samples were obtained 24 h before, immediately after and 18 h after official soccer matches. Student t-test or Mann-Whitney U-test was used to compare both groups throughout the match. RESULTS: At rest, we observed that the REC group had higher levels of total antioxidant status (TAS), glutathione peroxidase (GPx), and lower levels of creatine kinase (CK) and lactate dehydrogenase (LDH) in comparison to the NO-REC group. Immediately after the match, levels of TAS, GPx, superoxide dismutase (SOD), LDH and % lymphocytes were higher and the % of neutrophils were lower in the REC group compared to the NO-REC group. These differences were also maintained 18 h post-match, only for TAS and GPx. CONCLUSIONS: Our data reveal an association between nutritional intake and muscle damage, oxidative stress, immunity and inflammation markers. The benefit of the intake of specific nutrients may contribute to preventing the undesirable physiological effects provoked by soccer matches.

Applicability of an agility test in young players in the soccer field / Aplicabilidade de um teste de agilidade em jovens futebolistas em campo / Aplicabilidad de un test de agilidad en futbolistas jóvenes en el campo

INTRODUCTION: in soccer, agility is a relevant parameter that is defined as the ability to change the direction of the body rapidly and is a result of a combination of strength, speed, balance and coordination. OBJECTIVE: to demonstrated the reliability and validity of the modified Barrow test in soccer players aged 10 to 14 years, analyze its relationship with age, maturation, experience and body size and test the effectiveness of the protocol for distinguishing performance changes during a 10-month competitive season. METHODS: fifty-one adolescent Basque soccer players were enrolled. Age, maturation, experience, body size, vertical jump and 15-m sprint were measured. The reliability of the test was analyzed using replicate tests in a subgroup n = 34. Another subgroup of 33 players n =18, under-11, 10.4 ± 0.3 years; n = 15 under-13, 12.0 ± 0.8 years was evaluated at the beginning and the end of the season. RESULTS: the reliability of the test was good change in mean = -0.5%, 95% CI -1.2 to 0.2, SD=0.14; coefficient of variation = 0.9%, 95% CI - 0.7 to 1.5, SD=0.25. Chronological age and adiposity were significant predictors of agility performance P<0.01. An improvement in performance was observed over a 10-month soccer season, with a significant group effect P<0.01. CONCLUSION: the agility test demonstrated logic and validity, and proved to be a reliable and objective instrument for assessing adolescent soccer players. .

INTRODUÇÃO: a agilidade é um parâmetros relevante de desempenho no futebol, que pode de ser definido como a capacidade de alterar a direção do corpo com rapidez, sendo resultado da combinação de força, velocidade, equilíbrio e coordenação. OBJETIVO: demonstrar a confiabilidade e a validade do teste de Barrow modificado em jogadores de futebol com idade entre 10 e 14 anos, analisar sua relação com idade, amadurecimento, experiência e tamanho do corpo e comprovar a efetividade do protocolo para distinguir as mudanças no desempenho ao longo de uma temporada de 10 meses de competição. MÉTODOS: participaram 51 jovens jogadores de futebol bascos. Foram realizadas as seguintes mensurações: idade, maturação, experiência, composição corporal, salto vertical e corrida de velodidade de 15 metros. A confiabilidade do teste foi analisada pela repetição das medidas em um subgrupo de 34 jogadores n =18 sub-11, 10,4 ± 0,3 anos; n = 15 sub-13, 12,0 ± 0,8 anos. RESULTADOS: a confiabilidade do teste foi boa mudanças da média = -0,5%, IC 95% - 1,2 a 0,2, DP = 0,14; coeficiente de variação = 0,9%; IC 95% - 0,7 a 1,5, DP = 0,25. A idade cronológica e a adiposidade foram preditores do desempenho de agilidade P < 0,01. Foi observada melhora significante no desempenho durante os 10 meses de temporada, com efeito de grupo significante P < 0,01. CONCLUSÃO: o teste de agilidade demonstrou lógica e validade, além de ser um instrumento confiável e objetivo para avaliar a agilidade em jogadores de futebol adolescentes. .

INTRODUCCIÓN: en futbol, la agilidad es un parámetro relevante. Así, este parámetro está definido como la capacidad para cambiar de direcciones de forma rápida y es el resultado de una combinación de fuerza, velocidad, equilibrio y coordinación. OBJETIVO: demostrar la validez y confiabilidad del test modificado de Barrow en jóvenes jugadores de futbol de 10 a 14 años, analizar la relación con la edad, maduración, experiencia y tamaño corporal y comprobar la efectividad del protocolo para distinguir cambios de rendimiento durante una temporada competitiva de 10 meses. MÉTODOS: participaron 55 jugadores adolescentes vascos. Se realizaron las siguientes mediciones: edad, maduración, experiencia, composición corporal, salto vertical y sprint de 15 metros. La confiabilidad del test fue analizada mediante test replicado en un subgrupo de 34 jugadores. Otro subgrupo de 33 jugadores n = 18 sub-11, 10,4 ± 0,3 años; n = 15 sub-13, 12,0 ± 0,8 años fue analizado al principio y al final de la temporada. RESULTADOS: la confiabilidad del test fue buena cambios en la media = -0,5%, 95% IC - 1,2 a 0,2, ES-d = 0,14; el coeficiente de variación fue 0,9%, 95% IC - 0,7 a 1,5, ES-d = 0,25. La edad cronológica y la adiposidad fueron predictores del rendimiento de la agilidad P < 0,01. Se observó una mejora importante del rendimiento durante los 10 meses de temporada con un efecto de grupo significativo P < 0,01. CONCLUSIÓN: el test de agilidad demostró lógica y validez además de ser un instrumento confiable y objetivo para evaluar la agilidad en jugadores de futbol adolescentes. .