Does muscle imbalance affect fatigue after soccer specific intermittent protocol?

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

Aspectos nutricionais do futebol de competição

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Serum and plasma hormonal concentrations are sensitive to periods of intensity and volume of soccer training

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

Hematological parameters and anaerobic threshold in Brazilian soccer players throughout a training program

We assessed the responses of hematological parameters and their relationship to the anaerobic threshold of Brazilian soccer players during a training program. Twelve athletes were evaluated at the beginning (week 0, T1), in the middle (week 6, T2), and at the end (week 12, T3) of the soccer training program. on the first day at 7:30 AM, before collecting the blood sample at rest for the determination of the hematological parameters, the athletes were conducted to the anthropometric evaluation. on the second day at 8:30 AM, the athletes had their anaerobic threshold measured. Analysis of variance with Newman-Keuls'post hoc was used for statistical comparisons between the parameters measured during the soccer training program. Correlations between the parameters analyzed were determined using the Pearson's correlation coefficient. Erythrocytes concentration, hemoglobin, and hematocrit were significantly increased from T1 to T2. The specific soccer training program led to a rise in erythrocytes, hemoglobin, and hematocrit from T1 to T2. We assumed that these results occurred due to the plasma volume reduction and may be explained by the soccer training program characteristics. Furthermore, we did not observe any correlation between the anaerobic threshold and the hematological parameters.

Rapid hamstrings/quadriceps strength capacity in professional soccer players with different conventional isokinetic muscle strength ratios

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

The influence of fluid ingestion on performance of soccer players during a match

The purpose of this study was to verify the effects of a carbohydrate-electrolyte drink on soccer performance. Twenty soccer players volunteered to participate in the study. Players were allocated to two assigned trials according to their positional roles in the team: CHO group (ingesting a 6% carbohydrate-electrolyte solution at regular 15 minutes intervals) and NCHO (ingesting no fluid) during 75 min on-field soccer game. During the trials, body mass loss, heart rate, time spent running, number of sprints and core temperature were measured. There were statistically significant changes (p < 0.05) in body mass loss (CHO: 1.14 ± 0.37 kg vs. NCHO: 1.75 ± 0.47 kg) and number of sprints performed (CHO: 14.70 ± 4.38 vs. NCHO: 10.70 ± 5.80) between groups. The main finding of the present study indicates that supplementation with a carbohydrate-electrolyte drink during a soccer match is beneficial in helping to prevent deterioration in performance. © Journal of Sports Science and Medicine (2004).

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.

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.

Small- and medium-sized enterprises' restructuring in a context of transition: a shared process: inter-player effects on efficient boundary choice in the Argentine manufacturing sector

Includes bibliography

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.

EMBRAER: from national champion to global player

Includes bibliography

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.