The relationship between onset of blood lactate accumulation, critical velocity, and maximal lactate steady state in soccer players

The objective of this study was to analyze the validity of the velocity corresponding to the onset of blood lactate accumulation (OBLA) and critical velocity (CV) to determine the maximal lactate steady state (MLSS) in soccer players. Twelve male soccer players (21.5 ± 1.0 years) performed an incremental treadmill test for the determination of OBLA. The velocity corresponding to OBLA (3.5 mM of blood lactate) was determined through linear interpolation. The subjects returned to the laboratory on 7 occasions for the determination of MLSS and CV. The MLSS was determined from 5 treadmill runs of up to 30-minute duration and defined as the highest velocity at which blood lactate did not increase by more than 1 mM between minutes 10 and 30 of the constant velocity runs. The CV was determined by 2 maximal running efforts of 1,500 and 3,000 m performed on a 400-m running track. The CV was calculated as the slope of the linear regression of distance run versus time. Analysis of variance revealed no significant differences between OBLA (13.6 ± 1.4 km·h-1) and MLSS (13.1 ± 1.2 km·h-1) and between OBLA and CV (14.4 ± 1.1 km·h-1). The CV was significantly higher than the MLSS. There was a significant correlation between MLSS and OBLA (r = 0.80), MLSS and CV (r = 0.90), and OBLA and CV (r = 0.80). We can conclude that the OBLA can be utilized in soccer players to estimate the MLSS. In this group of athletes, however, CV does not represent a sustainable steady-state exercise intensity. © 2005 National Strength & Conditioning Association.

Analysis of the distances covered by first division Brazilian soccer players obtained with an automatic tracking method

Methods based on visual estimation still is the most widely used analysis of the distances that is covered by soccer players during matches, and most description available in the literature were obtained using such an approach. Recently, systems based on computer vision techniques have appeared and the very first results are available for comparisons. The aim of the present study was to analyse the distances covered by Brazilian soccer players and compare the results to the European players', both data measured by automatic tracking system. Four regular Brazilian First Division Championship matches between different teams were filmed. Applying a previously developed automatic tracking system (DVideo, Campinas, Brazil), the results of 55 outline players participated in the whole game (n = 55) are presented. The results of mean distances covered, standard deviations (s) and coefficient of variation (cv) after 90 minutes were 10,012 m, s = 1,024 m and cv = 10.2%, respectively. The results of three-way ANOVA according to playing positions, showed that the distances covered by external defender (10642 ± 663 m), central midfielders (10476 ± 702 m) and external midfielders (10598 ± 890 m) were greater than forwards (9612 ± 772 m) and forwards covered greater distances than central defenders (9029 ± 860 m). The greater distances were covered in standing, walking, or jogging, 5537 ± 263 m, followed by moderate-speed running, 1731 ± 399 m; low speed running, 1615 ± 351 m; high-speed running, 691 ± 190 m and sprinting, 437 ± 171 m. Mean distance covered in the first half was 5,173 m (s = 394 m, cv = 7.6%) highly significant greater (p < 0.001) than the mean value 4,808 m (s = 375 m, cv = 7.8%) in the second half. A minute-by-minute analysis revealed that after eight minutes of the second half, player performance has already decreased and this reduction is maintained throughout the second half. ©Journal of Sports Science and Medicine (2007).

Leg muscles recruitment pattern in soccer players and active individuals during isometric contractions

This study aimed to compare the torque, torque ratio (Hamstrings:Quadriceps - H:Q), electromyographic (EMG) activity and EMG ratio (knee flexors:knee extensors EMG) in soccer players (SG, N=10) and active subjects (AG, N=10). Subjects performed three maximal voluntary isometric knee extensions and flexions at 45° and 90° to determine the peak torque and EMG activity. Torque and EMG activity of the knee flexor (biceps femoris [BF] and semitendinosus [ST]) were divided by the torque and EMG activity of the knee extensor (vastuls lateralis [VL] and rectus femoris [RF]) to calculate torque ratios (H:Q) and EMG ratios (BF:VL, BF:RF, ST:VL, ST:RF). The flexion torque was significantly higher for SG (p<0.05) in 45° and 90°. EMG activity for SG was significantly higher in agonist contractions for VL, RF and ST, and significantly lower in antagonist contractions for RF and ST when compared to AG Torque and EMG ratios were similar between groups and there were good correlations between torque ratio and BF:VL ratio (r=0.71, p=0.02) and BF:RF ratio (r=0.81, p=0.004) at 45. The EMG results could overestimate the joint balance calculated using torque ratios. Differences in recruitment pattern between soccer players and non-athletes can be related to the training routines and the EMG ratios presents applicable in trained populations.

Fatigue and rapid hamstring/quadriceps force capacity in professional soccer players

The aim of this study was to investigate the effect of fatigue induced by an exhaustive laboratory-based soccer-specific exercise on different hamstrings/quadriceps (H:Q) ratios of soccer players. Twenty-two male professional soccer players (23·1 ± 3·4 year) performed maximal eccentric (ecc) and concentric (con) contractions for knee extensors (KE) and flexors (KF) at 60° s-1 and 180° s-1 to assess conventional (Hcon:Qcon) and functional (Hecc:Qcon) ratios. Additionally, they performed maximal voluntary isometric contraction for KE and KF, from which the maximal muscle strength, rate of force development (RFD) and RFD H:Q strength ratio (RFDH:Q) were extracted. Thereafter, subjects were performed an exhaustive laboratory-based soccer-specific exercise and a posttest similar to the pretest. There was significant reduction in Hcon:Qcon (0·60 ± 0·06 versus 0·58 ± 0·06, P<0·05) and in Hecc:Qcon (1·29 ± 0·2 versus 1·16 ± 0·2, P<0·01) after the soccer-specific exercise. However, no significant difference between Pre and Post exercise conditions was found for RFDH:Q at 0-50 (0·53 ± 0·23 versus 0·57 ± 0·24, P>0·05) and 0-100 ms (0·53 ± 0·17 versus 0·55 ± 0·17, P>0·05). In conclusion, H:Q strength ratios based on peak force values are more affected by fatigue than RFDH:Q obtained during early contraction phase. Thus, fatigue induced by soccer-specific intermittent protocol seems not reduce the potential for knee joint stabilization during the initial phase of voluntary muscle contraction. copy; 2012 Scandinavian Society of Clinical Physiology and Nuclear Medicine.

Nutritional status, biological maturation and cardiorespiratory fitness in Azorean youth aged 11-15 years

Background: Sex and individual differences in biological maturity status can influence height, weight, and body fat. Thus, the rigorous control of these variables seems necessary for estimating overweight and obesity in adolescents. The aims of this study were to estimate the prevalence of overweight and obesity and over-fatness in Azorean adolescents and to examine the contributions of chronological age, sex, estimated maturity status, and cardiorespiratory fitness (CRF) to the risk of overweight and obesity and over-fatness. Methods. The sample comprised 1,206 youth aged 11-15 years (626 boys and 580 girls) from the Azores Islands, Portugal. Body mass, stature, and skinfolds (triceps and subscapular) were measured. Body mass index (BMI) was calculated and percent fat was predicted from skinfolds. Age- and sex-specific IOTF cut-off values of the BMI defined nutritional status. Biological maturation was estimated as present height expressed as a percentage of predicted adult (mature) stature. The CRF was analyzed from the 20-m shuttle run test. Results: The total prevalence rates of overweight/obesity and over-fatness were of 31% and 27%, respectively. Low CRF (unfit) and being average and advanced in maturity status were positively and significantly associated with overweight/obesity and with risk of being over-fatness in both sexes. Conclusions: High prevalence rates of overweight/obesity and over-fatness were identified in Azorean youth, and low CRF and advanced biological maturation were positively associated with overweight/obesity and over-fatness in our sample of adolescents. © 2013 Coelho-e-Silva et al.; licensee BioMed Central Ltd.

Flexibility, torque and kick performance in soccer: Effect of dominance

Aim: The aim of this study was to evaluate the knee flexor and extensor torques in isometric contractions, comparing the H:Q ratios, flexibility and maximal kick between dominant (DL) and non-dominant (NDL) limb of soccer players (SG) and active people (AG)Methods: Subjects performed maximal instep kicks with each limb, flexibility tests and maximal isometric voluntary contractions of the knee flexion and extension at 45° and 90° to determine peak torque of the DL and NDLKnee flexion torque was divided by the knee extension torque to calculate torque ratios (H:Q ratio)Results: The flexibility and maximal kick in SG was significantly higher than in AG for both the DL and NDL (P<0.05)The maximal kick of DL was significantly higher than in NDL in SG (P<0.01)Knee flexion torque in SG was significantly higher than in AG in the DL (P<0.05), and the H:Q ratio was similar between AG and SGConclusion: Dominance related differences were evident in the flexor torque and maximal kick for SG, probably related to the asymmetric demand in trainings, which present no effect on the flexibility© 2013 Elsevier Masson SAS.

Systemic CA-MRSA infection following trauma during soccer match in inner Brazil: Clinical and molecular characterization

Even though community-acquired methicillin resistant Staphylococcus aureus (CA-MRSA) was described a decade ago, reports from Brazil are scarce and cases occurred in large urban centers. We report MRSA sepsis in a 16-year-old male from a small town and who had no history of exposure to healthcare or recent travel. After trauma during a soccer match, he presented swelling in the right thigh, which evolved in a month to cellulitis complicated by local abscess, orchitis and pneumonia. The patient presented severe sepsis, with fever and respiratory failure. Laboratory findings included blood leukocyte counts above 40,000/mm3 and thrombocytopenia. He was submitted to mechanical ventilation and therapy with vancomycin and imipenem. He had a slow but favorable response to therapy and was discharged after six weeks of hospitalization. MRSA grew from blood cultures and respiratory aspirates obtained before antimicrobial therapy. The isolate belonged to sequence type 5, spa type t311, harbored SCCmec type IV and genes for Panton-Valentine leukocidin and Enterotoxin A. The pulsed-field gel electrophoresis pattern was distinct from North American classic CA-MRSA clones. However, the sequence type and the spa type revealed that the clone belong to the same clonal complex isolated in Argentina. This is the first CA-MRSA infection reported in that region, with significant epidemiologic and clinical implications. © 2013 Elsevier Inc.

Intra-abdominal fat is related to metabolic syndrome and non-alcoholic fat liver disease in obese youth

Background: Previous studies have shown an association between adiposity, especially intra-abdominal adipose tissue, and hemodynamic/metabolic comorbidities in adults, however it is not clear in pediatric population. The aim of the study was to analyze the relationship between non-alcoholic fatty liver disease (NAFLD) and components of metabolic syndrome (MS) with values of intra-abdominal (IAAT) and subcutaneous (SCAT) adipose tissue in obese children and adolescents.Methods: Cross-sectional study. Subjects: 182 obese sedentary children and adolescents (aged 6 to 16 y), identified by the body mass index (BMI). Measurements: Body composition and trunk fat by dual-energy X-ray absorptiometry- DXA; lipid profile, blood pressure and pubertal stage were also assessed. NAFLD was classified as absent (0), mild (1), moderate (2) and severe (3), and intra-abdominal and subcutaneous abdominal fat thickness were identified by ultrasound. The MS was identified according to the cut offs proposed by World Health Organization adapted for children and adolescents. The chi-square test was used to compare categorical variables, and the binary logistic regression indicated the magnitude of the associations adjusted by potential cofounders (sex, age, maturation, NAFLD and HOMA-IR).Results: Higher quartile of SCAT was associated with elevated blood pressure (p = 0.015), but not associated with NAFLD (p = 0.665). Higher IAAT was positively associated with increased dyslipidemia (p = 0.001), MS (p = 0.013) and NAFLD (p = 0.005). Intermediate (p = 0.007) and highest (p = 0.001) quartile of IAAT were also associated with dyslipidemia, independently of age, sex, maturation, NAFLD and HOMA-IR (homeostatic model assessment-insulin resistance).Conclusion: Obese children and adolescents, with higher IAAT are more prone to develop MS and NAFLD than those with higher values of SCAT, independent of possible confounding variables. © 2013 Silveira et al.; licensee BioMed Central Ltd.

Instrumentação biomecânica aplicada à análise do desempenho do chute em jogadores de futebol de campo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Burnout e enfrentamento em jogadores de futebol: fases pré e durante competição

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Youth purpose and life goals of students engaged in community and social activities

Purpose provides a moral compass for young people to apply their strengths and virtues in their lives. Deepen the studies about youth purpose may contribute to the design of new and more efficient moral education strategies, aiming the development of greater citizenship awareness, social justice and youth engagement in the construction of a society based on democracy, justice and social solidarity. This research paper explores the identification of life goals, the beyond the self or self-oriented purpose in life, a meaningful engagement in purposeful activities and the well-being and satisfaction with life in Brazilian youth engaged and not engaged in social and community issues.

Quem não sonhou em ser um jogador de futebol?: trabalho com projetos para reelaborar foregrounds

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Futebol juvenil: entre o imaginário e a materialidade da vida nas categorias de base no Brasil

The youth academies of Brazilian soccer form – in imaginary of poor children and young ones – a window for a better future. Before precarious objective conditions, the teams receive future athletes, without educational concern that support adult professional life. The contradictions - that set between habitus of professional soccer beginners and material living conditions offered for soccer youth academies - make an important space for procedure of educators.