Mauro Heleno Chagas

Analysis of lower limb asymmetries by isokinetic and vertical jump tests in soccer players.

Abstract Menzel, H-J, Chagas, MH, Szmuchrowski, LA, Araujo, SRS, de Andrade, AGP, and Resende de Jesus-Moraleida, F. Analysis of lower limb asymmetries by isokinetic and vertical jump tests in soccer players. J Strength Cond Res 27(5): 1370–1377, 2013—Assessment of lower extremity bilateral asymmetries in soccer players is important for both injury prevention and performance. The purpose of this investigation was to compare isokinetic knee extensor assessment of asymmetry with a more specific countermovement jump (CMJ). Forty-six Brazilian male professional soccer players participated in this study. The maximal power, maximal force and impulse were determined during CMJ and the total work and peak torque at 60, 180, and 300°·s−1 during isokinetic leg extension, separately for each leg. Factor analysis was performed for all investigated variables, and the diagnostic concordance between different criteria was analyzed by McNemar’s &khgr;2 test. The factor analysis showed that the isokinetic and CMJ tests were widely independent methods for the assessment of bilateral differences. Concordance of the diagnostic information could only be found between the maximal force during CMJ and the total work and peak torque at 180 and 300°·s−1 during isokinetic leg extension. Impulse and maximal power during CMJ on a double force platform appear to be appropriate additional variables for the identification of bilateral differences. Therefore, it might be pertinent to perform, in addition to isokinetic assessment, a vertical jump test on a force platform to assure widespread and reliable diagnostic information.

Force-displacement relationship during anteroposterior mobilization of the ankle joint.

OBJECTIVE The purpose of this study was to determinate the correlation between force and displacement during passive anteroposterior mobilization of the talus and the effect of this treatment technique on ankle dorsiflexion range of motion (ROM). METHODS This is an exploratory, methodological study. Maitland grades III and IV mobilization were applied on the right ankle of 25 healthy subjects (mean age +/- standard deviation, 25.08 +/- 3.01 years) by 2 randomized raters (A and B). Applied forces were measured using a small force plate and displayed for the rater on a computer monitor. Linear displacement of the ankle joint was quantified by a motion analysis system. Synchronization of these 2 systems was obtained by software. Dorsiflexion active ROM, before and after mobilization, was assessed using a biplane goniometer. Statistical analysis was performed using the Pearson correlation coefficient for force and displacement variables and the paired t test to compare dorsiflexion ROM mean values. RESULTS A fair positive correlation was found between force range and displacement (r = 0.370; P = .049, 1-tailed), and a fair negative correlation was found between minimum forces and displacement (r = 0.404; P = .035, 1-tailed), only for rater A data. Significant increase in dorsiflexion was found in the right ankle (P = .035), comparing ROM before and after mobilization, which did not occur in the left ankle. CONCLUSIONS These data do not support a linear force-displacement relationship during Maitland grades III and IV passive joint mobilization, although they confirmed an increase in ankle dorsiflexion ROM immediately after joint mobilization. The use of visual feedback may increase interrater reliability of forces applied during ankle joint mobilization.

Associação entre tempo de reação e de movimento em jogadores de futsal

O objetivo do presente estudo foi verificar a associacao entre tempo de reacao (TR) simples e o tempo de movimento (TM) em jogadores de futsal jovens (13,8 ± 0,5 anos, n = 16). O TR simples foi medido no aparelho Multipsy 821, pressionando com o dedo indicador uma tecla em resposta a um sinal luminoso. O TM, giro do corpo para direita ou esquerda, foi mensurado por meio de um sistema composto por um tapete de contato, fixado ao solo, e dois pares de fotocelulas. O inicio e o final do movimento foram registrados pela perda de contato do pe do atleta com o tapete de contato e quando o atleta ultrapassava um par de fotocelulas duplas, respectivamente. A distância entre o tapete de contato e o primeiro par de fotocelulas foi de 1,45 m. A analise estatistica nao indicou correlacao significativa entre as duas variaveis. Uma possivel explicacao para os resultados esta relacionada com a estrutura dos testes utilizados e a mensuracao do TR e TM em acoes motoras distintas. Pode-se concluir, que o desempenho do TR simples nao deve ser associado a potencialidade do atleta em realizar movimentos rapidos de giro.

Comparação de duas diferentes intensidades de alongamento na amplitude de movimento

O alongamento e uma pratica comum no treinamento da flexibilidade, porem existe uma deficiencia de informacoes especificas sobre os componentes da carga utilizados, em especial, sobre a intensidade do alongamento. O presente estudo teve como objetivo investigar o efeito agudo de duas diferentes intensidades de alongamento na amplitude de movimento (ADM) de extensao do joelho. Participaram deste estudo 14 voluntarios do sexo masculino. Os dois membros inferiores de cada participante foram avaliados, sendo que um membro executou o treinamento na intensidade submaxima de alongamento (TS, N=14) e o outro na intensidade maxima de alongamento (TM, N=14). O treinamento utilizou a tecnica passiva-estatica executando quatro repeticoes com duracao de 15 segundos. Foi encontrada diferenca estatisticamente significativa para os valores de ADM entre o pre-teste (68,0±10,5) e o pos-teste (74,0±10,0) no TM. Os valores de ADM para o pre-teste (68,9±14,0) e o pos-teste (71,0±14,4) no TS nao apresentaram diferenca significativa. Os resultados analisados atraves da ANOVA two-way apresentaram interacao significativa entre o grupo e o teste (F=1.26; df=8,62; p=0,007). O estudo demonstrou que o treinamento na intensidade maxima de alongamento promove aumento agudo da ADM. Dessa forma, os estudos que avaliam os componentes ideais da carga de treinamento na melhora da flexibilidade nao devem negligenciar o controle da intensidade do estimulo de alongamento.

Acute effect of constant torque and angle stretching on range of motion, muscle passive properties, and stretch discomfort perception.

Abstract Cabido, CET, Bergamini, JC, Andrade, AGP, Lima, FV, Menzel, HJ, and Chagas, MH. Acute effect of constant torque and angle stretching on range of motion, muscle passive properties, and stretch discomfort perception. J Strength Cond Res 28(4): 1050–1057, 2014—The aim of the present study was to compare the acute effects of constant torque (CT) and constant angle (CA) stretching exercises on the maximum range of motion (ROMmax), passive stiffness (PS), and ROM corresponding to the first sensation of tightness in the posterior thigh (FSTROM). Twenty-three sedentary men (age, 19–33 years) went through 1 familiarization session and afterward proceeded randomly to both CA and CT treatment stretching conditions, on separate days. An isokinetic dynamometer was used to analyze hamstring muscles during passive knee extension. The subjects performed 4 stretches of 30 seconds each with a 15-second interval between them. In the CA stretching, the subject reached a certain ROM (95% of ROMmax), and the angle was kept constant. However, in the CT stretching exercise, the volunteer reached a certain resistance torque (corresponding to 95% of ROMmax) and it was kept constant. The results showed an increase in ROMmax for both CA and CT (p < 0.001), but the increase was greater for CT than for CA (CA vs. CT in poststretching, p = 0.002). Although the PS decreased for both CA and CT (p < 0.001), the decrease was greater for CT than for CA (CA vs. CT in poststretching, p = 0.002). The FSTROM increased for both CA and CT, but the increase for CT was greater than that for CA (CA vs. CT in poststretching, p = 0.003). The greater increase in ROMmax for the CT stretch may be explained by greater changes in the biomechanical properties of the muscle-tendon unit and stretch tolerance, as indicated by the results of PS and FSTROM.

USEFULNESS OF THE JUMP-AND-REACH TEST IN ASSESSMENT OF VERTICAL JUMP PERFORMANCE

The objective was to estimate the reliability and criterion-related validity of the Jump-and-Reach Test for the assessment of squat, countermovement, and drop jump performance of 32 male Brazilian professional volleyball players. Performance of squat, countermovement, and drop jumps with different dropping heights was assessed on the Jump-and-Reach Test and the measurement of flight time, then compared across different jump trials. The very high reliability coefficients of both assessment methods and the lower correlation coefficients between scores on the assessments indicate a very high consistency of each method but only moderate covariation, which means that they measure partly different items. As a consequence, the Jump-and-Reach Test has good ecological validity in situations when reaching height during the flight phase is critical for performance (e.g., basketball and volleyball) but only limited accuracy for the assessment of vertical impulse production with different jump techniques and conditions.

The Effect of Double - Blind Carbohydrate Ingestion during 60 km of Self-Paced Exercise in Warm Ambient Conditions

This study evaluated double blind ingestions of placebo (PLA) versus 6% carbohydrate (CHO) either as capsules (c) or beverage (b) during 60 km self-paced cycling in the heat (32°C and 50% relative humidity). Ten well-trained males (mean ± SD: 26±3 years; 64.5±7.7 kg and 70.7±8.8 ml.kg−1.min−1 maximal oxygen consumption) completed four separate 60 km time trials (TT) punctuated by 1 km sprints (14, 29, 44, 59 km) whilst ingesting either PLAb or PLAc or CHOb or CHOc. The TT was not different among treatments (PLAb 130.2±11.2 min, CHOb 140.5±18.1 min, PLAc 143.1±29.2 min, CHOc 137.3±20.1 min; P>0.05). Effect size (Cohen’s d) for time was only moderate when comparing CHOb – PLAb (d = 0.68) and PLAb – PLAc (d = 0.57) whereas all other ES were ‘trivial’ to ‘small’. Mean speed throughout the trial was significantly higher for PLAb only (P<0.05). Power output was only different (P<0.05) between the sprints and low intensity efforts within and across conditions. Core and mean skin temperatures were similar among trials. We conclude that CHO ingestion is of little or no benefit as a beverage compared with placebo during 60 km TT in the heat.

Análise de dois treinamentos com diferentes durações de pausa entre séries baseadas em normativas previstas para a hipertrofia muscular em indivíduos treinados

The prescription of weight training programs for muscle hypertrophy are usually based on the values recommended by the literature for determining the training load. The prescription of the pause duration ranges from one to three minutes and comparisons between these two durations leads to differences in hormonal and metabolic adaptations and performance. There is a lack of studies investigating if is it possible the realization of the training program for hypertrophy with different pauses, and the significance of the addition of 30 seconds for recovery. The purpose of the present study was to analyze two different trainings for muscle hypertrophy with the same volume and intensity, but different rest periods between sets, at the bench press exercise. Twenty-six trained male volunteers took part in the training sessions. After the familiarization procedure and the 1 maximum repetition (1RM) test, the group took a four set exercise with 70% of 1 RM on the bench press, aiming to accomplish 12 repetition for each set, with a constant rest period of 90 and 120 seconds. No significant difference was found on the number of repetitions throughout the sets when comparing the results of the 90 and 120 second group. Despite the rest duration (90 or 120 sec) the performance lowered during the sets, registered by significant reduction in the number of repetitions. The results indicated that, even for trained individuals, there is a limitation to apply the reference values presented in the literature for muscle hypertrophy training. Moreover, the performance may be not different despite changing the rest interval from 90 to 120 seconds between sets.RESUMO Os programas de treinamento na musculacao sao comumente prescritos baseando-se em normativas de carga de treinamento sugeridas pela literatura. Dentre as normativas, a prescricao da duracao da pausa tem variado normalmente de um a tres minutos. Comparacoes entre intervalos de pausa de um e tres minutos mostram diferencas significativas na resposta hormonal, metabolica e no desempenho. Existe carencia de estudos que mostram se diferentes pausas sao suficientes para a realizacao das outras normativas previstas para o treinamento da hipertrofia e se um acrescimo de 30 segundos possibilita melhor recuperacao. O objetivo deste estudo foi analisar a realizacao de dois treinamentos baseados em normativas previstas para a hipertrofia muscular e diferenciadas pelas pausas de 90 e 120 segundos entre series, no exercicio supino executado na barra guiada. Participaram 26 voluntarios do sexo masculino, treinados em musculacao. Foram realizadas quatro sessoes de testes em quatro dias. Apos a realizacao dos procedimentos de familiarizacao e do teste de 1RM, o grupo realizou o exercicio no supino guiado a intensidade de 70% de 1RM em quatro series com o objetivo de alcancar 12 repeticoes por serie, com pausas de 90 ou 120 segundos distribuidas aleatoriamente em diferentes dias. Nao foi verificada diferenca significativa no numero de repeticoes nas series quando comparado o desempenho obtido pelos sujeitos nas duas pausas. Independente da duracao da pausa (90 ou 120 segundos) foi observada queda do rendimento no decorrer da realizacao das series, caracterizada pela reducao significativa no numero de repeticoes realizado. Os resultados mostraram limitacao da aplicacao das normativas previstas para o treinamento da hipertrofia muscular em individuos treinados. Alem disso, pode nao haver diferencas no desempenho com a alteracao da pausa entre series de 90 para 120 segundos.

Analysis of two training programs with different rest periods between series based on guidelines for muscle hypertrophy in trained individuals

The prescription of weight training programs for muscle hypertrophy are usually based on the values recommended by the literature for determining the training load. The prescription of the pause duration ranges from one to three minutes and comparisons between these two durations leads to differences in hormonal and metabolic adaptations and performance. There is a lack of studies investigating if is it possible the realization of the training program for hypertrophy with different pauses, and the significance of the addition of 30 seconds for recovery. The purpose of the present study was to analyze two different trainings for muscle hypertrophy with the same volume and intensity, but different rest periods between sets, at the bench press exercise. Twenty-six trained male volunteers took part in the training sessions. After the familiarization procedure and the 1 maximum repetition (1RM) test, the group took a four set exercise with 70% of 1 RM on the bench press, aiming to accomplish 12 repetition for each set, with a constant rest period of 90 and 120 seconds. No significant difference was found on the number of repetitions throughout the sets when comparing the results of the 90 and 120 second group. Despite the rest duration (90 or 120 sec) the performance lowered during the sets, registered by significant reduction in the number of repetitions. The results indicated that, even for trained individuals, there is a limitation to apply the reference values presented in the literature for muscle hypertrophy training. Moreover, the performance may be not different despite changing the rest interval from 90 to 120 seconds between sets.RESUMO Os programas de treinamento na musculacao sao comumente prescritos baseando-se em normativas de carga de treinamento sugeridas pela literatura. Dentre as normativas, a prescricao da duracao da pausa tem variado normalmente de um a tres minutos. Comparacoes entre intervalos de pausa de um e tres minutos mostram diferencas significativas na resposta hormonal, metabolica e no desempenho. Existe carencia de estudos que mostram se diferentes pausas sao suficientes para a realizacao das outras normativas previstas para o treinamento da hipertrofia e se um acrescimo de 30 segundos possibilita melhor recuperacao. O objetivo deste estudo foi analisar a realizacao de dois treinamentos baseados em normativas previstas para a hipertrofia muscular e diferenciadas pelas pausas de 90 e 120 segundos entre series, no exercicio supino executado na barra guiada. Participaram 26 voluntarios do sexo masculino, treinados em musculacao. Foram realizadas quatro sessoes de testes em quatro dias. Apos a realizacao dos procedimentos de familiarizacao e do teste de 1RM, o grupo realizou o exercicio no supino guiado a intensidade de 70% de 1RM em quatro series com o objetivo de alcancar 12 repeticoes por serie, com pausas de 90 ou 120 segundos distribuidas aleatoriamente em diferentes dias. Nao foi verificada diferenca significativa no numero de repeticoes nas series quando comparado o desempenho obtido pelos sujeitos nas duas pausas. Independente da duracao da pausa (90 ou 120 segundos) foi observada queda do rendimento no decorrer da realizacao das series, caracterizada pela reducao significativa no numero de repeticoes realizado. Os resultados mostraram limitacao da aplicacao das normativas previstas para o treinamento da hipertrofia muscular em individuos treinados. Alem disso, pode nao haver diferencas no desempenho com a alteracao da pausa entre series de 90 para 120 segundos.

Estudo da confiabilidade da força aplicada durante a mobilização articular ântero-posterior do tornozelo

Reliability Study on the Force Applied During Anteroposterior Mobilization of the Ankle Joint Background: Factors that contribute towards the efficiency of joint mobilization maneuvers is the intensity and reproducibility of the force applied during mobilization, by one or more examiners. Objective: To evaluate the intra and inter-examiner reliability of Maitland grade III and IV anteroposterior mobilization force on the ankle joint. Method: Two experienced examiners mobilized both ankles of thirty-five healthy subjects. A force platform was positioned under the calves of these subjects to detect the forces applied during the maneuvers. The signals were converted and recorded using the DasyLab 4.0 software. The maximum and minimum peak forces from the curves obtained were then analyzed. The intraclass correlation coefficient (ICC) was used to assess the intra and inter-examiner reliability. To evaluate any systematic error in the measurements, the paired t-test was utilized on the intra-examiner data and the t-test for independent samples for the inter-examiner data. The Bland & Altman method was used to assess the concordance limits for the measurements from the two examiners. Results: The data showed high intraexaminer reliability. The inter-examiner reliability was low and moderate for the maximum and minimum forces respectively, during anteroposterior mobilization of the ankle joint. Conclusions: These data suggest that the force applied during Maitland grade III and IV mobilization of the ankle joint presents high intra-examiner reliability and low inter-examiner reliability.