Hamstrings on focus: Are 72 hours sufficient for recovery after a football (soccer) match? A multidisciplinary approach based on hamstring injury risk factors and histology.

This study aimed to assess acute and residual changes in sprint-related hamstring injury (HSI) risk factors after a football (soccer) match, focusing on recovery within the commonly observed 72-h timeframe between elite football matches. We used a multifactorial approach within a football context, incorporating optical and ultrastructural microscopic analysis of BFlh (biceps femoris long head) muscle fibres, along with an examination of BFlh fibre composition. Changes in sprint performance-related factors and HSI modifiable risk factors were examined until 3 days after the match (MD +3) in 20 football players. BFlh biopsy specimens were obtained before and at MD +3 in 10 players. The findings indicated that at MD +3, sprint-related performance and HSI risk factors had not fully recovered, with notable increases in localized BFlh fibre disruptions. Interestingly, match load (both external and internal) did not correlate with changes in sprint performance or HSI risk factors nor with BFlh fibre disruption. Furthermore, our study revealed a balanced distribution of ATPase-based fibre types in BFlh, with type-II fibres associated with sprint performance. Overall, the results suggest that a 72-h recovery period may not be adequate for hamstring muscles in terms of both HSI risk factors and BFlh fibre structure following a football match.

Contemporary educational and behavior change strategies improve dietary practices around a match in professional soccer players.

BACKGROUND: The importance of nutrition in optimizing the health and performance of professional soccer players has been well established. Despite published practical recommendations for the dietary requirements for professional soccer players, many players fail to meet these guidelines. Thus, the primary purpose of this study was to assess the impact of targeted nutritional education and behavior change interventions on dietary intake in professional football players. Additionally, previous research within this population has reported elevations in resting metabolic rate (RMR) following match-play. Therefore, a further aim of this study was to examine whether any changes in dietary intake would influence RMR following match-play. METHODS: Twenty players from the professional development phase in an English Premier League club (age: 18.4 ± 1.0 years; body mass: 76.1 ± 6.0 kg; stature: 1.80 ± 0.07 m) were randomly assigned to an "Intervention" (INT) group (n = 10), who received numerous nutritional education and behavior change interventions, or a "Control" (CON) group (n = 10), who received no nutrition support. Dietary intake was assessed daily throughout the match-week (Match Day (MD)-2, MD-1, MD, MD + 1, and MD + 2), whilst RMR was assessed on MD-1, MD + 1, and MD + 2. Statistical analyses on the intervention effects on dietary intake and RMR were carried out using a two factor (group and day) analysis of variance (ANOVA) with a subsequent Bonferroni post-hoc test. RESULTS: Mean energy (3393 ± 852 vs. 2572 ± 577 kcal · day-1) and CHO (5.36 ± 1.9 vs. 3.47 ± 1.1 g · kg-1 BW · day-1) intake was significantly higher (p < 0.001) in the INT vs. CON group. Furthermore, the INT group implemented nutrition periodization practices as CHO intake was significantly increased on MD-1 (7.0 ± 1.7 g · kg-1 BM · day-1), MD (7.1 ± 1.4 g · kg-1 BM · day-1) and MD + 1 (5.1 ± 0.8 g · kg-1 BM · day-1). However, the CON group did not periodize their CHO intake and failed to meet the CHO recommendations on MD-1, MD, and MD + 1 (<4 g · kg-1 BM · day-1). Compared to MD-1, the RMR increased on MD + 1 and MD + 2 in both groups, although it was only statistically significant for the INT group (MD + 1 = +243 kcal · day-1; MD + 2 = +179 kcal · day-1). CONCLUSIONS: The implementation of targeted nutritional education and behavior change interventions resulted in improved dietary practices in professional football players and enabled better adherence to recommended guidelines. However, despite this, RMR was still elevated in the 24-48 h following match play. Thus, in order to optimize recovery, this finding further reinforces the need for professional football players to adopt strategies to meet energy, and particularly CHO, requirements in the acute period following a match in order to account for this increase in energy requirement.

Accuracy of a non-exercise method using seismocardiography for the estimation of V̇O2peak in sub-elite football players.

A non-exercise method equation using seismocardiography for estimating V̇O2peak (SCG V̇O2peak) has previously been validated in healthy subjects. However, the performance of the SCG V̇O2peak within a trained population is unknown, and the ability of the model to detect changes over time is not well elucidated. Forty-seven sub-elite football players were tested at the start of pre-season (SPS) and 36 players completed a test after eight weeks at the end of the pre-season (EPS). Testing included an SCG V̇O2peak estimation at rest and a graded cardiopulmonary exercise test (CPET) on a treadmill for determination of V̇O2peak. Agreement between SCG V̇O2peak and CPET V̇O2peak showed a large underestimation at SPS (bias ± 95% CI: -9.9 ± 1.8, 95% Limits of Agreement: 2.2 to -22.0 mL·min-1 kg-1). At EPS no interaction (p = 0.3590) but a main effect of time (p < 0.0001) and methods (p < 0.0001) was observed between SCG and CPET V̇O2peak. No correlation in V̇O2peak changes was observed between SCG and CPET (r = -20.0, p = 0.2484) but a fair agreement in classifying the correct directional change in V̇O2peak with the SCG method was found (Cohen's κ coefficient = 0.28 ± 0.25). Overall, the SCG V̇O2peak method lacks accuracy and despite being able to estimate group changes, it was incapable of detecting individual changes in V̇O2peak following a pre-season period in sub-elite football players. The SCG algorithm needs to be further adjusted and the accuracy and precision improved for the method to be applicable for use within a trained population.

Assessment of Maximum Oxygen Uptake in Elite Youth Soccer Players: A Comparative Analysis of Smartwatch Technology, Yoyo Intermittent Recovery Test 2, and Respiratory Gas Analysis.

The maximum oxygen uptake (VO2max) is a critical factor for endurance performance in soccer. Novel wearable technology may allow frequent assessment of V̇O2max during non-fatiguing warm-up runs of soccer players with minimal interference to soccer practice. The aim of this study was to assess the validity of VO2max provided by a consumer grade smartwatch (Garmin Forerunner 245, Garmin, Olathe, USA, Software:13.00) and the YoYo Intermittent Recovery Run 2 (YYIR2) by comparing it with respiratory gas analysis. 24 trained male youth soccer players performed different tests to assess VO2max: i) a treadmill test employing respiratory gas analysis, ii) YYIR2 and iii) during a non-fatiguing warm-up run of 10 min wearing a smartwatch as recommended by the device-manufacturer on 3 different days within 2 weeks. As the device-manufacturer indicates that validity of smartwatch-derived VO2max may differ with an increase in runs, 16 players performed a second run with the smartwatch to test this claim. The main evidence revealed that the smartwatch showed an ICC of 0.37 [95% CI: -0.25; 0.71] a mean absolute percentage error (MAPE) of 5.58% after one run, as well as an ICC of 0.54 [95% CI: -0.3; 8.4] and a MAPE of 1.06% after the second run with the smartwatch. The YYIR2 showed an ICC of 0.17 [95% CI: -5.7; 0.6]; and MAPE of 4.2%. When using the smartwatch for VO2max assessment in a non-fatiguing run as a warm-up, as suggested by the device manufacturer before soccer practice, the MAPE diminishes after two runs. Therefore, for more accurate VO2max assessment with the smartwatch, we recommend to perform at least two runs to reduce the MAPE and enhance the validity of the findings.

Effects of far-infrared radiation lamp therapy on recovery from a simulated soccer-match in elite female soccer players.

We investigated the effects of far-infrared radiation (FIR) lamp therapy on changes in muscle damage and performance parameters following six sets of 15-min Loughborough intermittent shuttle test (LIST), a simulated soccer match. Twenty-four elite female soccer players (20-24 y) were assigned into FIR or sham treatment group (n = 12/group). The participants received a 60-min FIR or sham treatment (30 min per muscle) over knee extensors (KE) and flexors (KF) at 2, 25, 49, 73, and 97 h post-LIST. Maximal voluntary isometric contraction (MVC) torque and muscle soreness of the KE and KF, plasma creatine kinase (CK) activity as muscle damage markers, and several performance parameters including countermovement jump (CMJ) and Yo-Yo intermittent recovery test level 1 (YYIR1) were measured before and 1, 24, 48, 72, 96, and 120 h post-LIST. Changes in the measures were compared between groups by a mixed-design two-way ANOVA. The running distance covered during LIST and changes in the measures at 1-h post-LIST (before the treatment) were similar (p = 0.118-0.371) between groups. Changes in muscle damage markers at 24-120 h post-LIST were smaller (p < 0.05, η2 = 0.208-0.467) for the FIR (e.g., MVC-KE torque decrease at 48-h post-LIST: -1 ± 2%, peak KE soreness: 16 ± 10 mm, peak CK: 172 ± 42 IU/L) than sham group (-11 ± 9%, 33 ± 7 mm, 466 ± 220 IU/L, respectively). Performance parameters recovered faster (p < 0.05, η2 = 0.142-0.308) to baseline for the FIR (e.g., decreases at 48-h post-LIST; CMJ: 0 ± 1%, YYIR1: 0 ± 1%) than sham group (-6 ± 2%, -9 ± 6%, respectively). These results suggest that the FIR lamp therapy was effective for enhancing recovery from a soccer match.

How Does Altering the Volume-Load of Plyometric Exercises Affect the Inflammatory Response, Oxidative Stress, and Muscle Damage in Male Soccer Players?

Incorporating plyometric exercises (PE) into soccer players' conditioning routines is vital for boosting their performance. Nevertheless, the effects of PE sessions with diverse volume loads on inflammation, oxidative stress, and muscle damage are not yet clearly understood. This study aimed to examine the effects of altering the volume-loads of PE on indicators of oxidative muscle damage and inflammation. The study involved forty young male soccer players who were randomly assigned to three different volume-loads of PE (Low volume-load [100 jumps]: LVL, n = 10; Moderate volume-load [150 jumps]: MVL, n = 10; and High volume-load [200 jumps]: HVL, n = 10) and a control group (CON = 10). The levels of various biomarkers including delayed onset muscle soreness (DOMS), serum lactate dehydrogenase (LDH), creatine kinase (CK), 8-hydroxy-2-deoxyguanosine (8-OHdG), malondialdehyde (MDA), protein carbonyl (PC), leukocytes, neutrophils, interleukin-6 (IL-6), and C-reactive protein (CRP) were measured at different time points. These measurements were taken at rest, immediately after completion of PE, and 24-, 48-, and 72-hours post-PE. The CK, LDH, DOMS, 8-OHdG, MDA, and PC levels were significantly increased (p < 0.05) after the PE protocol, reaching their peak values between 24 to 48 hours post-PE for all the volume-loaded groups. The levels of leukocytes, neutrophils, and IL-6 also increased after the PE session but returned to resting values within 24 hours post-PE. On the other hand, CRP levels increased at 24 hours post-PE for all the treatment groups (p < 0.05). The changes observed in the indicators of muscle damage and inflammation in response to different volume-loads of PE was not significant. However, the HVL and MVL indicated significant differences compared to LVL in the 8-OHdG (at 48-hour) and MDA (at 72-hour). Athletes engaging in higher volume-loads demonstrated more pronounced responses in terms of biochemical variables (specifically, LVL < MVL < HVL); however, these changes were not statistically significant (except 8-OHdG and MDA).

Is digit ratio (2D:4D) a biomarker for lactate? Evidence from a cardiopulmonary test on professional male footballers.

BACKGROUND: Lactate accumulation is associated with vigorous exercise, cardiovascular disease and a number of cancers. Digit ratio (2D:4D) has also been linked to oxygen metabolism, myocardial infarction and various cancers. Such similarities suggest the possibility that 2D:4D is a biomarker of lactate. Here, we consider the relationship between 2D:4D and lactate during an incremental cardiopulmonary exercise test. METHOD: The participants were male professional football players. The treadmill test began at a speed of 8 km/h when the first lactate measurement was taken. The speed was increased by 2 km/h every 3.15 min, with measurements at 10, 12, 14 and 16 km/h. RESULTS: There were 72 Caucasian and 7 Black participants, results are reported for the most numerous group. Lactate levels increased with running speed and were not correlated with age, body size or body composition. Median splits of digit ratios (right, left and right-left 2D:4D [Dr-l]) were calculated. In comparison to the Low ratio group, the High ratio group showed higher lactate levels across speeds. Effect sizes varied from very large to huge (right 2D:4D), large (left 2D:4D) and medium (Dr-l). At the individual level, positive correlations between digit ratios and lactate at the five different speeds varied from large (right 2D:4D), medium (left 2D:4D) and small (Dr-l). CONCLUSION: There were large positive associations between right 2D:4D and lactate at all running speeds. We discuss our findings in relation to oxygen metabolism and suggest that 2D:4D may be a biomarker for lactate in the wider context of the latter's importance in health and disease.

Muscular and cardiorespiratory parameters of Brazilian professional futsal players: comparison between top national and regional level athletes

Abstract Aim: To compare muscular and cardiorespiratory parameters between Brazilian professional futsal athletes from different competitive levels (national versus regional). A secondary aim was to explore the correlation of physical fitness variables between both competitive levels. Methods: Twenty-two futsal players (24.7 ± 3.7 years), 11 from a regional team and 11 from a national team, were evaluated with countermovement jump test (lower limbs muscle power), square test (the speed with change direction), RSSA (anaerobic power), and YOYOIR1 (aerobic power). Tests were performed in the middle of the season for both teams. Results: The speed with change direction (p = 0.001) and mean anaerobic power (p = 0.04) were higher for national than the regional players. Sprint performance decreased similarly for national and regional level players (p < 0.001), but the latter had poorer performance (p = 0.044). From the fourth sprint on, sprints for the national level players were slower than the first three, while for the regional level players, each sprint speed was slower than the subsequent. A significant correlation was found between anaerobic power with jump height (r = −0.50; p = 0.01), speed with change direction (r=0.65; p = 0.001) and distance covered in the YOYOIR1 (r = −0.54; p = 0.01). Conclusion: National-level athletes were more agile and presented a higher mean anaerobic power than regional ones. Moreover, national-level athletes presented better performance along with repeated sprint tests, maintaining this performance for a longer time during the test.

Body composition among university female athletes of team sports / Composición corporal entre atletas universitarias de deportes colectivos / Composição corporal entre atletas universitárias de esportes coletivos

ABSTRACT Introduction: The assessment of body composition in female athletes of different sports is important for health monitoring. Objective: To compare body composition in university athletes of different team sports (indoor soccer, flag football and volleyball). Methods: A cross-sectional study carried out with 45 female athletes, aged 18 to 35 years (22.8 ± 3.55). The dependent variables were body fat mass (FM) and fat-free mass (FFM) measured by air displacement plethysmography. Bone mineral content, adjusted for height (BMC/height) and bone mineral density (BMD), were measured by dual energy X-ray absorptiometry. The independent variable was sport [flag football (n = 12); indoor soccer (n = 20); volleyball (n = 13)] and the covariates were age (complete years), training volume (minutes per week) and length of time playing the sport (complete years). Analysis of covariance was used. Results: Adjusting the model for covariates, volleyball athletes (19.27 kg ± 2.20) presented higher FM values compared to the flag football (16.00 kg ± 1.70) and indoor soccer players (12.20 kg ± 1.30). There was no significant difference in FFM, BMC/height and total BMD between sports, even after adjusting for covariates. Conclusion: Volleyball athletes presented higher FM compared to flag football and indoor soccer athletes. There were no differences in FFM, BMC/height and BMD among the players of the different team sports. This study can help coaches and other sports professionals to prevent injuries to athletes in sports such as higher FM (volleyball), or to prevent diseases such as menstrual irregularities, which are common in athletes who may have low levels of body fat (indoor soccer players), this being one of the risk factors for the female athlete triad (eating disorders, menstrual irregularities and low BMD). Level of evidence III; Retrospective comparative study .

RESUMEN Introducción: La evaluación de la composición corporal en atletas del sexo femenino de diferentes modalidades deportivas es importante para la monitorización de la salud. Objetivos: Comparar la composición corporal de atletas universitarias, de diferentes modalidades colectivas (fútbol de salón, flag football y vóleibol). Métodos: Estudio transversal realizado con 45 atletas del sexo femenino, con edades entre 18 y 35 años (22,8 ± 3,55). Las variables dependientes fueron la masa grasa (MG) y masa magra (MM) medida por pletismografía por desplazamiento de aire. El contenido mineral óseo ajustado para estatura (CMO/estatura) y densidad mineral ósea (DMO) fueron medidos por absorciometría por doble emisión de rayos X. Las variables independientes fueron los deportes [flag football (n = 12); fútbol de salón (n = 20); vóleibol (n = 13)] y las covariables fueron edad (años completos), volumen de entrenamiento (minutos por semana) y tiempo de práctica (años completos). Fue utilizado el análisis de covariancia. Resultados: Al ajustar el modelo por las covariables, las atletas de vóleibol (19,27 kg ± 2,20) presentaron valores mayores de MG con relación a las de flag football (16,00 kg ± 1,70) y de fútbol de salón (12,20 kg ± 1,30). No hubo diferencia significativa en la MM, CMO/estatura y DMO total entre los deportes, incluso después del ajuste para las covariables. Conclusiones: Las atletas de vóleibol presentaron mayor MG en comparación con los atletas de flag football y fútbol de salón. No hubo diferencias en MM, CMO/estatura y DMO entre las jugadoras de diferentes modalidades colectivas. Este estudio puede ayudar a entrenadores y otros profesionales del deporte a prevenir lesiones en atletas con mayor MG (vóleibol) o prevenir enfermedades como irregularidades menstruales, comunes en atletas con bajos niveles de grasa corporal (fútbol de salón), que es uno de los factores de riesgo para el síndrome de la tríada de la atleta femenina (disturbios alimentarios, irregularidades menstruales y baja DMO). Nivel de evidencia III; Estudio retrospectivo comparativo .

RESUMO Introdução: A avaliação da composição corporal em atletas do sexo feminino de diferentes modalidades esportivas é importante para o monitoramento da saúde. Objetivos: Comparar a composição corporal de atletas universitárias, de diferentes modalidades coletivas (futebol de salão, flag football e voleibol). Métodos: Estudo transversal realizado com 45 atletas do sexo feminino, com idades entre 18 e 35 anos (22,8 ± 3,55). As variáveis dependentes foram a massa gorda corporal (MG) e a massa magra (MM) medida por pletismografia por deslocamento de ar. O conteúdo mineral ósseo ajustado para estatura (CMO/estatura) e densidade mineral óssea (DMO) foram medidos por absorciometria por dupla emissão de raios X. As variáveis independentes foram os esportes [flag football (n = 12); futebol de salão (n = 20); voleibol (n = 13)] e as covariáveis foram idade (anos completos), volume de treinamento (minutos por semana) e tempo de prática (anos completos). A análise de covariância foi utilizada. Resultados: Ao ajustar o modelo pelas covariáveis, as atletas de voleibol (19,27 kg ± 2,20) apresentaram valores maiores de MG com relação às de flag football (16,00 kg ± 1,70) e de futebol de salão (12,20 kg ± 1,30). Não houve diferença significativa na MM, CMO/estatura e DMO total entre os esportes, mesmo depois do ajuste para as covariáveis. Conclusões: As atletas de voleibol apresentaram maior MG em comparação com as atletas de flag football e futebol de salão. Não houve diferenças em MM, CMO/estatura e DMO entre os jogadoras de diferentes modalidades coletivas. Este estudo pode ajudar treinadores e outros profissionais do esporte a prevenir lesões em atletas com maior MG (voleibol) ou prevenir doenças como irregularidades menstruais, comuns em atletas com baixos níveis de gordura corporal (futebol de salão), que é um dos fatores de risco para a síndrome da tríade da atleta feminina (distúrbios alimentares, irregularidades menstruais e baixa DMO). Nível de evidência III; Estudo retrospectivo comparativo .

Reference values of the body composition of young chilean soccer players / Valores de referencia de la composición corporal de jóvenes futbolistas chilenos / Valores de referência da composição corporal de jovens futebolistas chilenos

ABSTRACT Objective: To analyze whether fat mass (FM) and fat-free mass (FFM) should be evaluated by chronological age and/or biological age and propose curves to classify the body composition of young Chilean soccer players. Methods: A cross-sectional descriptive study was developed. Six hundred and forty-two soccer players between 13.0 and 18.9 years of age were recruited. Body mass, height, trunk-cephalic height, and tricipital and subscapular skinfolds were evaluated. Biological maturation was determined using peak height velocity age (PHV) and the percentage of fat mass was estimated by regression equations. The reference percentiles were calculated using the LMS method. Results: The values of R2 were lower for chronological age (FM = 0.07% and FFM = 0.13%) than for biological age (FM = 0.31% and FFM = 0.50%). Eleven percentiles (p3, p5, p10, p15, p25, p50, p75, p85, p90, p95 and p97) were calculated for FFM and FM. Conclusion: Biological age (PHV) is a better predictor of FFM and FM than chronological age. The references proposed can be used to monitor the body composition of young Chilean soccer players. Level of Evidence II; Diagnostic Study .

Resumen Objetivo: Analizar si la masa grasa (MG) y la masa libre de grasa (MLG) deben ser evaluadas por la edad cronológica y/o por la edad biológica, y proponer curvas para clasificar la composición corporal de jóvenes futbolistas chilenos. Métodos: Se elaboró un estudio descriptivo transversal. Fueron reclutados 642 futbolistas entre 13,0 y 18,9 años. Fueron medidas masa corporal, estatura, altura tronco-cefálica, pliegues cutáneos tricipital y subescapular. La madurez biológica fue determinada por la edad de pico de velocidad de crecimiento (EPVC) y el porcentual de masa grasa fue estimado por ecuaciones de regresión. Los percentiles de referencia fueron calculados por el método LMS. Resultados: Los valores de R2 para edad cronológica fueron menores (MG=0,07% y MLG=0,13%) en comparación con los valores para la edad biológica (MG=0,31% y MLG=0,50%). Fueron calculados 11 percentiles (p3, p5, p10, p15, p25, p50, p75, p85, p90, p95 y p97) para la MLG y MG. Conclusión: La edad biológica (EPVC) es un predictor mejor de la MLG y de la MG que la edad cronológica. Las referencias propuestas pueden servir para monitorizar la composición corporal de jóvenes futbolistas chilenos. Nivel de evidencia II; Estudio de diagnóstico .

RESUMO Objetivo: Analisar se a massa gorda (MG) e a massa livre de gordura (MLG) devem ser avaliadas pela idade cronológica e/ou pela idade biológica, e propor curvas para classificar a composição corporal de jovens futebolistas chilenos. Métodos: Elaborou-se um estudo descritivo transversal. Foram recrutados 642 futebolistas entre 13,0 e 18,9 anos. Massa corporal, estatura, altura tronco-cefálica, dobras cutâneas tricipital e subescapular foram medidas. A maturação biológica foi determinada pela idade de pico de velocidade de crescimento (IPVC) e o percentual de massa gorda foi estimado por equações de regressão. Os percentis de referência foram calculados pelo método LMS. Resultados: Os valores de R2para idade cronológica foram menores (MG = 0,07% e MLG=0,13%) em comparação com os valores para a idade biológica (MG = 0,31% e MLG = 0,50%). Foram calculados 11 percentis (p3, p5, p10, p15, p25, p50, p75, p85, p90, p95 e p97) para a MLG e MG. Conclusão: A idade biológica (IPVC) é um preditor melhor da MLG e da MG do que a idade cronológica. As referências propostas podem servir para monitorar a composição corporal de jovens futebolistas chilenos. Nível de evidência II; Estudo de diagnóstico .

Analysis of athletes' running ability data mining algorithm based on the dynamic characteristics of football players / Análise do algoritmo de mineração de dados da capacidade de corrida de atletas com base nas características dinâmicas dos jogadores de futebol / Análisis del algoritmo de minería de la capacidad de correr de los jugadores de fútbol basado en las características dinámicas de los jugadores de fútbol

ABSTRACT In 2008, our country successfully held the Olympic Games, where China won the most gold medals. After these Olympic Games, China has also become a world sports power. Our country's table tennis, diving, skating and other sports are also in the leading ranks in the world. In this study, according to the current training status of Chinese football players, we used data mining algorithm to analyze the unawareness of acceleration and speed of Chinese athletes in the running process. In this study, these indicators were quantified and analyzed, which has successfully promoted the training level of Chinese football players.

RESUMO Em 2008, nosso país sediou os Jogos Olímpicos, em que a China ganhou a maior parte das medalhas de ouro. Após os Jogos Olímpicos, a China também se tornou uma potência esportiva mundial. O tênis de mesa, o salto ornamental, a patinação e outros esportes também estão em posições de liderança. Neste estudo, de acordo com o atual estado de treinamento dos jogadores de futebol chineses, usamos o algoritmo de mineração de dados para analisar a falta de aceleração e velocidade dos atletas chineses na corrida. No estudo, esses indicadores foram quantificados e analisados, elevando o nível do treinamento os jogadores de futebol chineses.

RESUMEN En 2008, China celebró con éxito los Juegos Olímpicos.China ganó la mayoría de las medallas de oro en los Juegos Olímpicos.Después de los Juegos Olímpicos, China también se ha convertido en una potencia deportiva mundial.El tenis de mesa, el buceo y el patinaje sobre hielo en China también están en la posición de liderazgo en el mundo.De acuerdo con la situación actual del entrenamiento de los jugadores de Fútbol en nuestro país, este trabajo analiza la falta de percepción de la aceleración y velocidad de los jugadores de Fútbol en el proceso de correr con el algoritmo de minería.Y en los resultados de la investigación, el análisis cuantitativo de estos indicadores ha mejorado con éxito el nivel de entrenamiento de los jugadores de fútbol chinos.

Influencing factors of college students' physical health under the intervention of football / Fatores de influência da saúde física de estudantes universitários sob a intervenção do futebol / Análisis de los factores que influyen en la salud física de los estudiantes universitarios bajo la intervención del fútbol

ABSTRACT The current football can effectively exercise the body of college students and improve their physical health. How to use modern intelligent technology to perform quantitative research on the influencing factors of football on college students' physical health is the current development trend. Based on this, this paper studies the influencing factors of college students' physical health under the intervention of football. First of all, this paper puts forward an analysis model of college students' physical health based on the sarsa algorithm. The autocorrelation function is used to simulate and process the students' physical information. Through the maximum value of the autocorrelation function curve in the detection process, the detection signal is restored, then the error of the sarsa algorithm is analyzed. Secondly, this paper expounds the influence factors of sarsa algorithm on students' physical health in football. Fuzzy evaluation method and analytic hierarchy process are used in the evaluation. Aiming at the shortcomings of AHP, the improved sarsa algorithm is used for comprehensive analysis, and an adaptive simulation evaluation system is established. Finally, the effectiveness of the sarsa algorithm in this system is verified by many football experiments.

RESUMO O futebol atual pode efetivamente exercitar o corpo de estudantes universitários e melhorar sua saúde física. Como usar a tecnologia moderna inteligente para realizar pesquisas quantitativas sobre os fatores que influenciam o futebol na saúde física dos estudantes universitários é a tendência de desenvolvimento atual. Com base nisso, este documento estuda os fatores que influenciam a saúde física dos estudantes universitários sob a intervenção do futebol. Em primeiro lugar, este artigo apresenta um modelo de análise da saúde física dos estudantes universitários com base no algoritmo sarsa. A função de autocorrelação é usada para simular e processar as informações físicas dos alunos. Através do valor máximo da Curva da função de autocorrelação no processo de detecção, o sinal de detecção é restaurado, e então o erro do algoritmo de sarsa é analisado. Em segundo lugar, este documento expõe os fatores de influência do algoritmo sarsa sobre a saúde física dos estudantes no futebol. O método de avaliação aproximado e o processo hierárquico analítico são utilizados na avaliação. Visando as deficiências do AHP, o algoritmo de sarsa melhorado é usado para uma análise abrangente, e um sistema de avaliação de simulação adaptável é estabelecido. Finalmente, a eficácia do algoritmo sarsa neste sistema é verificada por diversos experimentos com futebol.

RESUMEN El fútbol actual puede ejercitar eficazmente el cuerpo de los universitarios y mejorar su salud física. La tendencia de desarrollo actual es como utilizar la moderna tecnología inteligente para realizar investigaciones cuantitativas sobre los factores del fútbol que influyen sobre la salud física de los estudiantes universitarios. Con base en esto, este trabajo estudia los factores que influyen en la salud física de los estudiantes universitarios por la intervención del fútbol. En primer lugar, este artículo presenta un modelo de análisis de la salud física de los estudiantes universitarios basado en el algoritmo sarsa. La función de autocorrelación se utiliza para simular y procesar la información física de los estudiantes. Por medio del valor máximo de la curva de la función de autocorrelación en el proceso de detección, se restaura la señal de detección, luego se analiza el error del algoritmo sarsa. En segundo lugar, este artículo expone los factores de influencia del algoritmo sarsa en la salud física de los estudiantes en el fútbol. En la evaluación se utilizan el método de evaluación difusa y el proceso de jerarquía analítica. Apuntando a las deficiencias de PJA, el algoritmo mejorado de sarsa se utiliza para un análisis integral y se establece un sistema de evaluación de simulación adaptativa. Finalmente, la efectividad del algoritmo sarsa en este sistema es verificada por muchos experimentos de fútbol

Football society players over the age of 55: how stressful can a match be?

This study aimed atassessingthe physical activitylevel, heart rate and the salivary cortisol level of football society players.The sample consisted of 19 male mastersfootballplayerswith an average age of 56.7±3.9 years. The long form of the International Physical Activity Questionnaire (IPAQ)andPolar®heart rate monitors were usedas instruments, in additionto Salivette® tubes to measure salivary cortisol. Data analysis was performed by using the repeated measuresAnalysis of Variance (ANOVA) with Bonferroni post hoctest,and Spearman's Rank Correlation Coefficient. The results showed that the salivary cortisol concentration indicated an index of 1.97 ng/ml at the beginning of the match;40 minutes after that thesevalues increased to 8.00 ng/ml,and 60 minutesafter the match had started they reached 8.40 ng/ml. Considering the post-match moment, a moderate and positive correlation between the salivary cortisol concentration and heart rate (averageand maximum) wasseen. In conclusion,the physical effort expended during football Society practice needs to be monitored due to the high heart rate and high increase in the salivary cortisol concentrationofthis age group.

The effects of basketball and soccer training on arterial stiffness / Efeitos do treinamento de basquetebol e futebol sobre a rigidez arterial / Efectos del entrenamiento de básquetbol y fútbol sobre la rigidez arterial

ABSTRACT Objective The purpose of this study was to examine arterial stiffness in elite basketball and soccer athletes by pulse wave velocity. Methods The cohort comprised 35 healthy male volunteers aged 17 to 26 years. All the subjects were either basketball players (n=9), soccer players (n=12) or sedentary controls (n=14). Arterial stiffness was measured by the Pulse Trace System (Micro Medical Ltd., Rochester, UK) and echocardiographic images were taken using a commercially available machine (Vivid 7 GE-Vingmed, Horten, Norway) with a 2.5 MHz transducer. Results The basketball players had significantly higher heights and body weights as compared to both the soccer players and the controls. The aortic elastic properties derived from the echocardiographic measurements did not differ between the groups. The peripheral pulse wave velocity measurements showed significantly lower values both in the basketball and soccer players compared to the controls, whereas the central pulse wave velocity measurement was significantly lower only in the basketball players as compared to the controls. No significant difference was seen between the basketball and soccer players. Conclusions The results of this study show that football and basketball exercises comprised of aerobic, anaerobic, endurance balance-coordination and sport-specific training play a role in reducing arterial stiffness. Level of evidence I; type of study: prognostic study.

RESUMO Objetivo O propósito deste estudo foi examinar a rigidez arterial em atletas de basquetebol e futebol medindo a velocidade da onda do pulso. Métodos A coorte foi composta por 35 voluntários saudáveis do sexo masculino, com idade entre 17 a 26 anos. Os participantes eram jogadores de basquetebol (n = 9), jogadores de futebol (n = 12) e controles sedentários (n = 14). A rigidez arterial foi medida com o Pulse Trace System (Micro Medical Ltd., Rochester, Reino Unido) e as imagens ecocardiográficas foram obtidas com um aparelho disponível no mercado, com transdutor de 2,5 MHz (Vivid 7 GE-Vingmed, Horten, Noruega). Resultados Os jogadores de basquetebol tinham estatura e peso corporal consideravelmente superiores aos dos jogadores de futebol e aos controles. As propriedades elásticas aórticas derivadas das medicas ecocardiográficas não diferiram entre os grupos. A velocidade da onda de pulso periférico foi significativamente menor nos jogadores de basquetebol e futebol em comparação com os controles, enquanto os jogadores de basquetebol tiveram velocidade da onda do pulso central consideravelmente menor que os controles. Não se observou diferença significativa entre os jogadores de basquetebol e os de futebol. Conclusões Os resultados deste estudo mostram que os exercícios de treinamento de futebol e basquetebol: aeróbicos, anaeróbicos, de resistência, de coordenação e equilíbrio e os treinamentos específicos de cada esporte têm um papel importante na redução da rigidez arterial. Nível de Evidência I, Estudo prognóstico.

RESUMEN Objetivo El propósito de este estudio fue examinar la rigidez arterial en atletas de básquetbol y fútbol midiendo la velocidad de onda de pulso. Métodos La cohorte fue compuesta por 35 voluntarios saludables del sexo masculino, con edad entre 17 y 26 años. Los participantes eran jugadores de básquetbol (n=9), jugadores de fútbol (n=12) y controles sedentarios (n=14). La rigidez arterial fue medida con Pulse Trace System (Micro Medical Ltd., Rochester, Reino Unido) y las imágenes ecocardiográficas fueron obtenidas con un aparato disponible en el mercado, con transductor de 2,5 MHz (Vivid 7 GE-Vingmed, Horten, Noruega). Resultados Los jugadores de básquetbol tenían estatura y peso corporal considerablemente superiores a los de los jugadores de fútbol y a los de los controles. Las propiedades elásticas aórticas derivadas de las medidas ecocardiográficas no difirieron entre los grupos. La velocidad de onda de pulso periférico fue significativamente menor en los jugadores de básquetbol y fútbol en comparación con los controles, mientras que los jugadores de básquetbol tuvieron velocidad de onda de pulso central considerablemente menor que los controles. No se observó diferencia significativa entre los jugadores de básquetbol y los de fútbol. Conclusiones Los resultados de este estudio muestran que los ejercicios de entrenamiento de fútbol y básquetbol: aeróbicos, anaeróbicos, de resistencia, de coordinación y equilibrio y los entrenamientos específicos de cada deporte tienen un papel importante en la reducción de la rigidez arterial. Nivel de Evidencia I, Estudio pronóstico.

Acute effect of speed test on the skin temperature of elite soccer players / Efeito agudo do teste de velocidade sobre a temperatura da pele de jogadoras de futebol de elite / Efecto agudo del test de velocidad sobre la temperatura de la piel de jugadoras de fútbol de élite

ABSTRACT Introduction Infrared thermography has been used in several areas, mainly in sports training, and specifically in soccer. Objectives The objectives of the study were to verify the acute effect of a displacement speed test on the skin temperature of elite female soccer players, to observe pre- and post-test thermal asymmetries, and to compare responses in the anterior and posterior regions of lower limbs. Methods Cross-sectional study that evaluated 17 soccer players of the 2018 Brazilian Championship. They were submitted to thermography before and 10 minutes after performing the displacement speed test. Thermographic images were collected using a FLIR® model 8 thermal imager and changes in skin temperature in the anterior and posterior regions of the lower limbs were analyzed, according to the areas of interest. Descriptive statistics were performed and mean and standard deviation of the temperatures of the areas of interest were analyzed. The normality of the data was verified, and then the Student's t test for normal paired and independent samples and the Mann-Whitney test for non-normal samples were conducted, with p <0.05 being adopted for significance level. Results It was possible to observe that after the test there was an increase in skin temperature in all the regions analyzed, both on the dominant and non-dominant sides (p <0.05). Regarding the analysis of the anterior region, it was possible to observe a higher temperature (p <0.05) in the region of the tibial muscles than in the region of the quadriceps muscles. Conclusion It is concluded that thermography helps to understand the thermal responses of lower limbs after applying the displacement speed test. The study shows that thermographic evaluation can guide the organization of the training session when motor tests have previously been applied, and in the detection of abnormal overloads, helping to prevent injuries. Level of evidence IV; Therapeutic studies - Investigation of treatment results.

RESUMO Introdução A termografia infravermelha tem sido empregada em diversas áreas, principalmente no treinamento esportivo e especificamente no futebol. Objetivos Os objetivos do estudo foram verificar o efeito agudo da aplicação de um teste de velocidade de deslocamento sobre a temperatura da pele de atletas de futebol feminino de elite, as assimetrias térmicas pré e pós-teste e comparar respostas nas regiões anterior e posterior de membros inferiores. Métodos Estudo de caráter transversal, que avaliou 17 jogadoras de futebol do Campeonato Brasileiro em 2018. Elas foram submetidas à termografia antes e 10 minutos depois da realização do teste de velocidade de deslocamento. Foram coletadas imagens termográficas por meio de um termovisor FLIR®, modelo E8, e analisadas as alterações da temperatura da pele, na região anterior e posterior dos membros inferiores, de acordo com as áreas de interesse. Foi realizada a estatística descritiva e para análise, foram usados média e desvio padrão da temperatura das áreas pretendidas. Verificou-se normalidade dos dados e, em seguida, o teste t de Student para amostras normais pareadas e independentes e o teste de Mann-Whitney, para amostras não normais, adotando-se p < 0,05 para nível de significância. Resultados Foi possível observar que depois do teste houve aumento da temperatura da pele em todas as regiões analisadas, tanto no lado dominante quanto no não dominante (p < 0,05). Com relação à análise da região anterior, foi possível observar maior temperatura (p < 0,05) na região dos músculos tibiais quando comparados com os músculos da região do quadríceps. Conclusão Conclui-se que a termografia auxilia o entendimento das respostas térmicas de membros inferiores depois da aplicação do teste de velocidade de deslocamento. O estudo demonstra que a avaliação termográfica pode orientar a organização da sessão de treinamento quando há aplicação prévia de testes motores e na detecção de sobrecargas anormais, auxiliando na prevenção de lesões. Nível de evidência IV; Estudos terapêuticos - Investigação dos resultados do tratamento.

RESUMEN Introducción La termografía infrarroja ha sido empleada en diversas áreas, principalmente en el entrenamiento deportivo y específicamente en el fútbol. Objetivos Los objetivos del estudio fueron verificar el efecto agudo de la aplicación de un test de velocidad de desplazamiento sobre la temperatura de la piel de atletas de fútbol femenino de élite, las asimetrías térmicas pre y post test y comparar respuestas en las regiones anterior y posterior de miembros inferiores. Métodos Estudio de carácter transversal, que evaluó a 17 jugadoras de fútbol del Campeonato Brasileño en 2018. Ellas fueron sometidas a termografía antes y 10 minutos después de la realización del test de velocidad de desplazamiento. Fueron colectadas imágenes termográficas por medio de un termovisor FLIR® - E8, modelo E8, y analizadas las alteraciones de la temperatura de la piel, en la región anterior y posterior de los miembros inferiores, de acuerdo con las áreas de interés. Fue realizada la estadística descriptiva y para el análisis, fueron usados promedio y desviación estándar de la temperatura de las áreas pretendidas. Se verificó normalidad de los datos y, a continuación, el test t de Student para muestras normales pareadas e independientes, y el test de Mann-Whitney, para muestras no normales, adoptándose p < 0,05 para nivel de significancia. Resultados Fue posible observar que después del test hubo aumento de la temperatura de la piel en todas las regiones analizadas, tanto en el lado dominante como en el no dominante (p <0,05). Con relación al análisis de la región anterior, fue posible observar mayor temperatura (p <0,05) en la región de los músculos tibiales cuando comparados con los músculos de la región del cuádriceps. Conclusión Se concluye que la termografía ayuda en el entendimiento de las respuestas térmicas de miembros inferiores, después de la aplicación del test de velocidad de desplazamiento. El estudio demuestra que la evaluación termográfica puede orientar la organización de la sesión de entrenamiento cuando hay aplicación previa de tests motores y en la detección de sobrecargas anormales, ayudando en la prevención de lesiones. Nivel de evidencia IV; Estudios terapéuticos - Investigación de los resultados del tratamiento.

Physiological and technical demands of the small-sided and generic games in female futsal players

Abstract Aim: This study aimed to compare the heart rate (HR) values and technical actions frequencies during small-sided (SSG) and generic (GG) games in women futsal players. Methods: Six futsal players (age: 20.5 ± 7.4 years, height: 163.3 ± 16 cm, body mass: 57.9 ± 22 kg, maximum rate of oxygen consumption (VO2max): 42.0 ± 9 mL.kg.min−1) performed two experimental conditions in two days separated for at least 72h of interval: (1) one set of 10 min of SSG, 3x3 players; and (2) one set of 10 min of GG, 4 (1 joker) x 4 (1 joker) players. During each experimental session, the subject's HR values were monitored every 1 min of play. Pass, shot, dribbling, driving, and disarmament were recorded during the games. Results: There was no difference between SSG and GG for HR average (p = 0.50). The HR values that were recorded at the first minute of GG were higher than SSG (p = 0.02). The HRmax in SSG and GG were equivalent to 91.9% and 90.8% of HRmax of the incremental test, respectively. Total technical actions were higher in SSG (+ 18.4%, p = 0.001) than GG. Pass was higher in the SSG (+16%; p = 0.01) in comparison to GG. Conclusion: Both models were higher than HRmax equivalent to AT velocity. The technical actions of the SSG were higher than GG, suggesting that the SSG model is a suitable technical and physiological stimulus for the development of female futsal players.

Effects of soccer training during preseason on physical and physiological variables in youth soccer players

Abstract Aim: This study aimed to explore the effects of a training program during the pre-season on aerobic and anaerobic performance, hemodynamics, autonomic variables, and sleep quality in youth soccer players. Methods: Nineteen athletes, with an average age of 17 ± 1 years, participated in the study. The multicomponent training protocol was divided into technical, tactical, and physical practice for four weeks. The cardiac autonomic modulation was obtained through an electrocardiogram and blood pressure values were measured by a sphygmomanometer. The athletes answered the Pittsburgh questionnaire that assessed sleep patterns and issues. The VO2max was analyzed using the Intermittent Recovery Test Yo-Yo level 1. The RAST test was used to assess anaerobic power. Results: There was improvement in Heart Rate Variability (HRV) indicated by the increase in indexes, mean square root of the differences between normal cycles (RMSSD), low frequency increase (LF) (p = 0.04; d = 0.70), high frequency decrease (HF) (p = 0.01; d = 1.02) and the LF / HF sympathovagal index (p = 0.03; d = 0.70), variables related to faster recovery. An improvement in the components of sleep duration (p = 0.03) and quality (p = 0.02) of baseline and post-intervention sleep was also observed. Conclusion: The four-week multicomponent protocol contributed to improving VO2max, improving fatigue rates, quality of sleep, and maximum power. Additionally, we observe that youth soccer athletes had physiological and hemodynamic adaptations that resulted in an improvement in cardiac autonomic modulation and sleep patterns after four weeks of training.

El peroné: mal alumno, pero buen profesor. (¿Qué tiene prioridad biológica: la integridad, o la supervivencia?) / Fibula: a bad pupil but a good profesor. (What comes first, integrity or survival?)

La concepción original del mecanostato como un regulador de la rigidez estructural ósea orientado a mantener un determinado 'factor de seguridad' en todos los esqueletos parece no corresponder por igual a cualquier hueso y para cualquier tipo de estímulo. Hemos descubierto que la estructura cortical diafisaria del peroné humano manifiesta un comportamiento ambiguo del sistema, referido al uso del pie. La diáfisis peronea, además de ser insensible al desuso, se rigidiza, como sería de esperar, por entrenamientos en disciplinas deportivas que rotan o revierten el pie (hockey, fútbol, rugby); pero, llamativamente, se flexibiliza en su mitad proximal por entrenamiento en carrera larga, que optimiza el rendimiento del salto que acompaña a cada paso. La referida rigidización robustecería la región peronea de inserción de los músculos que rotan o revierten el pie, favoreciendo la locomoción sobre terrenos irregulares o 'gambeteando', propia de especies predadoras como los leopardos. La 'inesperada' flexibilización proximal, pese a reducir la resistencia a la fractura por flexión lateral (poco frecuente en el hombre), favorecería la absorción elástica de la energía contráctil de la musculatura inserta, optimizando el rendimiento del salto al correr, condición vital para especies presas como las gacelas. La falta de analogía de estas respuestas de la estructura peronea a distintos entrenamientos, incompatible con el mantenimiento de un factor de seguridad, sugiere su vinculación preferencial con la optimización de aptitudes esqueléticas con valor selectivo. Esto ampliaría el espectro regulatorio del mecanostato a propiedades esqueléticas 'vitales', más allá del control de la integridad ósea. Su manifestación en el hombre, ajena a connotaciones selectivas (quizá resultante del mantenimiento de genes ancestrales), permitiría proponer la indicación de ejercicios orientados en direcciones preferenciales a este respecto, especialmente cuando estas coincidieran con las de las fuerzas que podrían fracturar al hueso. (AU)

The original notion of the mechanostat as a regulator of bone structural rigidity oriented to maintain a certain 'safety factor' in all skeletons does not seem to correspond equally to every bone and for any type of stimulus. We have discovered that the diaphyseal cortical structure of the human fibula shows an ambiguous behavior of the system, with reference to the use of the foot. The peroneal shaft, in addition to being insensitive to disuse, becomes stiffened, as might be expected, by training in sport disciplines that involve rotating or reversing the foot (hockey, soccer, rugby); but, remarkably, it becomes more flexible in its proximal half by long-distance running training, which optimizes the performance of the jump that accompanies each step. The stiffening would strengthen the peroneal region of insertion of the muscles that rotate or reverse the foot, favoring locomotion on uneven terrain or 'dribbling', typical of predatory species such as leopards. The 'unexpected' proximal flexibilization, despite reducing the resistance to lateral flexion fracture (rare in human), would favor the elastic absorption of contractile energy from the inserted muscles, optimizing jumping performance when running, a vital condition for prey species such as gazelles. The lack of analogy of these responses of the peroneal structure to different training, incompatible with the maintenance of a safety factor, suggests its preferential link with the optimization of skeletal aptitudes with selective value. This would expand the regulatory spectrum of the mechanostat to 'vital' skeletal properties, beyond the control of bone integrity. Its manifestation in humans, oblivious to selective connotations (perhaps resulting from the maintenance of ancestral genes), would make it possible to propose the indication of exercises oriented in preferential directions, especially when they coincide with the direction of the forces that could fracture the bone. (AU)