BackgroundKnee valgus during landing and cutting situations has been described as the main biomechanical risk factor for anterior cruciate ligament (ACL) injuries. Evidence support the influence of ...hip strength and biomechanics on knee valgus in female athletes. To develop specific preventive measures for males, it is important to understand biomechanical and musculoskeletal variables associated with this mechanism during activities that mimic ACL injuries.ObjectiveTo test the correlation between peak knee valgus during a single-leg vertical jump-landing task, and biomechanical and musculoskeletal variables in male soccer professional athletes.DesignCross-sectional study.SettingBiomechanics laboratory.ParticipantsTwenty-four healthy male professional soccer players.InterventionsParticipants performed a vertical jump-landing task during the pre-season. Kinematic data were collected using an 8 high-speed cameras motion analysis system (Vicon, Oxford, UK) with a sample rate of 250 Hz. Maximal isometric hip strength was tested using a hand-held dynamometer and ankle dorsiflexion range of motion was measured using a digital inclinometer.Main Outcome MeasurementsPredictor variables were lateral trunk lean, hip adduction and internal rotation, hip extensors, abductor and external rotator isometric strength, and ankle dorsiflexion range of motion. Interest variables were peak knee valgus during the landing task. Association between predictors and interest variables were tested using Pearson Correlation Coefficient (alpha = 0.05).ResultsLateral trunk lean (r =0.43, p=0.04) and hip internal rotation (r =-0.68, p<0.01) showed significant correlation with peak knee valgus during the vertical landing task.ConclusionsTrunk position seems to influence the ACL mechanism, possibly by increasing knee abduction moment related to the lateral displacement of centre of mass during lateral trunk lean. The negative correlation between hip internal rotation and knee valgus in males is opposite to the results usually described for females, and may be related to the different influence of hip on ACL injury mechanism between sexes.
Introduction. The purpose of this study was to assess the isometric muscle strength (IMS) of the knee extensors and flexors, bilateral asymmetry (BA) and the hamstring: quadriceps ratio (H:Q ratio) ...between the dominant leg (DL) vs. the non-dominant leg (NDL) of males trained with free-weights vs. machines. Material and Methods: Thirty males were recruited and separated into two groups: Free-weights (n = 15) and Machines (n = 15) groups. All study participants performed the IMS testing for knee extensors and flexors in the DL and NDL using a commercially available load cell. The highest value obtained from the three trials was used for statistical analysis. Results: The IMS of the quadriceps and hamstring muscles for DL and NDL showed a significant increase in the Free-weight group when compared to the Machine group. In addition, a significant difference (p <.03) in the IMS of hamstring muscles between DL vs. NDL was observed in the Machine group. The H:Q ratio on DL (p < .002) and NDL (p < .01) was significantly higher in the Free-weight group. Conclusion: This study showed better isometric muscle strength of the thigh (hamstring and quadriceps) and the H:Q ratio in males trained with free weights. In addition, males trained with machines showed a bilateral asymmetry of the hamstring muscles and a lower H:Q ratio – consequently, a higher risk of knee injuries.
The purpose of this study was to compare balance, functional performance and isometric hip strength muscle among males practitioners of resistance training (RT) with Free-weights and Machines. Thirty ...males were recruited and separated into two groups: Free-weights (n = 15) and Machines (n = 15). Free-weights group showed a routine of RE that engaged the whole body with resistance bands, free-weights, dumbbells, and medicine balls. Conversely, machine group trained only exercises on machines. All participants underwent three tests to assess balance, functionality, and isometric muscle strength. All tests were performed in a single assessment session in the following order: Y Balance test; functional performance testing; and maximal isometric hip strength, respectively. The two-way ANOVA yielded main effects for group in the anterior (F1,22= 12.11, p < .002), posteromedial (F1,22= 16.87, p < .0005), posterolateral (F1,22= 15.97, p < .0006) and composite (F1,22= 21.39, p < .0001) in performance during YBT between free-weight vs. machines group for both legs. Single leg step down (SLSD) and Single leg hop (SLH) test demonstrating better functional performance in the free-weight group for both legs (p<.001). Isometric muscle strength of hip abduction and extension showed lower in the machines when compared to free-weight group for both legs. This study showed greater balance, functional performance and isometric muscle strength of hip abduction and extension in males trained with Free-weight. Males trained with machine showed lower functional performance, balance and bilateral asymmetry of the hip extensor muscles strength and risk of injuries.
: This study compared the effects of intermittent negative pressure therapy (INPT) vs. active recovery therapy (ART) on post-match physiological parameters such as serum CK level and skin temperature ...of the lower limbs in elite soccer players.
: Twenty healthy male professional soccer players from a Brazilian first division soccer club were enrolled in this randomized, parallel arm, open label, comparative study. After participating in 2 soccer matches, they were randomly assigned to two groups (n = 10) to receive a 30-min session of INPT (intermittent exchange of hypobaric pressure range 33 to 51 mmHg) or ART (self-myofascial release, mobility and stability exercises, and cycle ergometer exercise). The intervention was conducted after a match with assessments immediately before and after the intervention and again 24 h after the intervention.
: A significant interaction effect (F
= 4.503, p = 0.018, η
= 0.130) was observed, indicating that the decrease of CK from pre-intervention to 24 h post-intervention was greater in the INPT than in the ART group. Lower limb skin temperature was significantly lower after INPT than after ART (p < 0.003).
: Serum CK level and skin temperature of lower limbs showed better recovery up to 24 h after the intervention with INPT in elite soccer players.
The aim of this study was to test the correlation between knee-to-hip flexion ratio during a single leg landing task and hip and knee strength, and ankle range of motion. Twenty-four male ...participants from a professional soccer team performed a continuous single leg jump-landing test during 10s, while lower limb kinematics data were collected using a motion analysis system. After biomechanical testing, maximal isometric hip (abduction, extension, external rotation), knee extension and flexion strength were measured. Maximum ankle dorsiflexion range of motion was assessed statically using the weight bearing lunge test. Pearson correlation coefficients were calculated to determine the associations between the predictor variables (knee and hip strength, and ankle ROM) and the main outcome measure (knee-to-hip flexion ratio). Correlation between knee-to-hip flexion ratio and hip abductors strength was significant (r = −0.47; p = 0.019). No other significant correlations were observed among the variables (p > 0.05). These results demonstrated that a lower hip abductors strength in male soccer players was correlated with a high knee-to-hip flexion ratio during landing from a single leg jump, potentially increasing knee overload by decreasing energy absorption at the hip. The results provide a novel proposal for the functioning of hip muscles to control knee overload.
The aim of the study was to compare rest QT interval and QTcorrected intervals of electrocardiogram in trained men with and without cervical spinal cord injury (CSCI) and investigate cardiac ...electrocardiogram parameters in trained men with CSCI submitted to maximal effort test. Thirty men were separated into three groups: Control without CSCI (CON, 25.3 ± 4.1 yrs, strength training: 3 days week-1; aerobic training 1day week-1; n = 10), high volume exercise (30.5 ± 4.3 yrs, 3 day week-1 rugby specific exercises, 60min. day-1; n = 12) and moderate volume of exercise (33.7 ± 5.9 yrs, 2 days week-1 specific rugby exercises, 60 min. day-1; n = 8) with incomplete CSCI (C5-C7 cervical vertrebae) more than 12 months. Electrocardiogram was recorded in rest, during and after effort test. QT interval was significantly reduced (p = 0.001) in the high volume exercise group compared to control. Corrected QT interval showed no difference between moderate vs. high volume exercise group (p > 0.05). No changes were observed in QT, corrected QT, PR and QRS intervals of electrocardiogram between rest and post effort (p > 0.05). Thus, effort test does not change electrocardiogram parameters in CSCI subjects. High volume of week exercise promotes abnormalities in cardiac repolarization compared to a moderate training program.
Introdução: a avaliação da percepção de esforço (PSE) e estados de humor (EH) em diferentes intensidades de esforço, pode auxiliar o planejamento do programa de treinamento minimizando o risco de ...overtraining e lesões osteomioarticulares.Objetivo: comparar as respostas de PSE e estados de humor em individuos submetidos a duas intensidades distintas de corrida de 5km.Métodos: corredores de rua recreacionais (n: 14) do Clube de Corrida da Universidade Federal de Sergipe (UFS) foram submetidos a um teste de 5Km. Posteriormente a realização do teste todos os individuos foram submetidos a dois testes de 5km randomizados com diferentes intensidades sendo a 95% e 85% da velocidade do teste de 5km. Foram avaliados o tempo total, a veocidade media, a percepçaõ de esforço, a carga interna e os parámetros vigor e fadiga.Resultados: O protocolo de corrida C5K85 apresentou redução significativa (p 0,001) das variáveis velocidade média de corrida, PSE e CIT quando comparado ao protocolo C5K95. A variável fadiga apresentou aumento significativo (p 0,001) pós-esforço no protocolo C5K95, sem mudanças significativas no protocolo C5K85 (p0,05). Conclusão: a percepção subjetiva de esforço, a carga interna de treino e a subescala fadiga do questionário BRUMS podem ser utilizados como ferramentas para controle e monitoramento da intensidade de treinamento em corredores de 5km.
O objetivo deste trabalho de revisão foi dissertar sobre a regulação hormonal da ingestão alimentar e dopeso corporal. A ingestão de macronutrientes, o gasto energético e o balanço entre a síntese de ...hormô-nios que aumentam a atividade dos neurônios orexígenos e anorexígenos são fatores determinantesna regulação da ingestão alimentar e no controle do peso corporal. Os hormônios leptina, insulina e opeptídeo YY são grandes potenciadores da atividade dos neurônios anorexígenos POMC/CART. Poroutro lado, a ação da grelina aumenta a atividade dos neurônios orexígenos NPY/AgRP. Estes hormônios sintetizados perifericamente atravessam a barreira-hemato-encefálica e se ligam aos seus receptores no núcleo arqueado hipotalâmico com o objetivo de regular a ingestão alimentar e controlar obalanço energético. Estes mecanismos revelam a complexidade do controle do balanço energético etodos os centros envolvidos na busca pela homeostase energética
The aim was investigate the time-course of cardiac autonomic response in men with incomplete cervical spinal cord injury (SCI) practitioners or not of physical exercise. Twenty men were separated ...into three groups: control group without SCI (CON; 28.3 ± 4.5 yrs; 178.4 ± 6.5 cm; 82.1 ± 6.8 kg; n=8), regularly engaged in strength training and low aerobic training; exercise group with cervical SCI (EG, 32.3 ± 4.5 yrs, 175.1 ± 5.3 cm, 73.6 ± 9.6 Kg; n=8) that practiced wheelchair rugby and sedentary group with cervical SCI (SG, 30.8 ± 5.3 yrs, 173.4 ± 10.1 cm, 69.7 ± 7.1 Kg; n=4) who did not practice physical exercise. Heart rate variability variables were calculated from ECG, in rest. CON showed high values compared to EG and SG of: standard deviation of R-R intervals (SDNN), proportion of adjacent R-R intervals differing by more than 50 ms, number of interval differences of successive NN intervals greater than 50 ms, root mean square of successive differences and the high-frequency spectral power. SDNN was significantly lower in EG compared to CON. changes in cardiac autonomic function could be noted in subjects with cervical SCI regularly engaged in an exercise program.
Abstract Aims The aim of this study was to establish thermographic profiles of lower limbs and to correlate them with creatine kinase level in professional players. Method Thirty healthy male ...professional soccer players (25.4 ± 4.7 years; 179.5 ± 6.7 cm; 78.3kg ± 7.5 kg; body fat 10.2 ± 4.2 %) from a club of Brazilian first division soccer league volunteered. Thermal images sequences of lower limbs (thighs and legs) were acquired in an anteroposterior manner (i.e., frontal and dorsal views) by a digital infrared thermo-camera. Blood creatine kinase (CK) concentration was assessed by reflectance photometry. All thermographic images and CK were performed between 8:00 and 9:00 am. Results No significant difference (p>0.05) was found between left and right sides from both anterior and posterior measurements of thighs and legs for mean or maximal skin temperature. Low values of correlation (range r=0.14 to r=0.38) was found between skin temperature and CK levels while contralateral thermal symmetry in the lower limbs (regions of interest < 0.2°C) was found. Conclusion It was observed contralateral thermal symmetry in the lower limbs and low correlation between CK and temperature values in elite soccer players.
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