Validity, reliability and measurement error of quadriceps femoris muscle thickness obtained by ultrasound in healthy adults: a systematic review / Validade, confiabilidade e erro da medida da espessura muscular do quadríceps femoral obtida pela ultrassonografia em adultos saudáveis: uma revisão sistemática

Abstract Due to its low cost and operational simplicity, ultrasound has been used to monitor muscle thickness in laboratory environments, rehabilitation clinics, and sports clubs. However, it is necessary to determine the measurement's quality to infer whether the possible changes observed are derived from the treatment or the measurement error. Therefore, we performed a systematic review to determine the validity, reliability, and measurement error of quadriceps femoris muscle thickness obtained by ultrasound in healthy adults. A search was conducted in the Pubmed, Scopus, and Web of Science databases until April 2022. The study selection process was carried out by two independent researchers, with the presence of a third researcher in case of disagreements. Twenty-six studies were eligible for the review, being 4 of validity, 4 of reliability only, and 18 of reliability and measurement error. The intraclass correlation coefficient ranged from 0.60 to 0.99 in validity studies and from 0.44 to 0.99 in reliability studies. The typical error of measurement ranged from 0.01 to 0.47 cm, and the coefficient of variation was from 0.5 to 17.9%. Four studies received "very good" classification in all the risk of bias analysis criteria. Therefore, it is concluded that the quadriceps femoris muscle thickness obtained by ultrasound was shown to be valid, reliable, and to have low measurement errors in healthy adults. The weighted average of the relative error was 6.5%, less than typical increases in resistance training studies. The raters' experience and methodological care for repeated measurements were necessary to observe low measurement errors.

Resumo Devido ao baixo custo e simplicidade operacional, a ultrassonografia tem sido utilizada para monitorar a espessura muscular em ambientes laboratoriais, clínicas de reabilitação e clubes desportivos. Porém, é necessário determinar a qualidade da medida para inferir se as possíveis modificações observadas são decorrentes do tratamento ou do erro da medida. Portanto, realizamos uma revisão sistemática para determinar a validade, confiabilidade e erro da medida da espessura muscular do quadríceps femoral obtida pela ultrassonografia em adultos saudáveis. Foi realizada busca nas bases de dados Pubmed, Scopus e Web of Science até abril de 2022. O processo de seleção dos estudos foi realizado por dois pesquisadores independentes, com a presença de um terceiro pesquisador em caso de divergências. Vinte e seis estudos foram elegíveis para a revisão, sendo 4 de validade, 4 apenas de confiabilidade e 18 de confiabilidade e erro de medida. O coeficiente de correlação intraclasse variou de 0,60 a 0,99 em estudos de validade e 0,44 a 0,99 em estudos de confiabilidade. O erro típico da medida variou de 0,01 a 0,47 cm e o coeficiente de variação foi de 0,5 a 17,9%. Quatro estudos receberam classificação "muito bom" em todos os critérios na análise de risco de viés. Portanto, concluiu-se que a espessura muscular do quadríceps femoral obtida pela ultrassonografia se mostrou válida, confiável e com baixos erros de medida em adultos saudáveis. A média ponderada do erro relativo foi de 6,5%, menor do que os aumentos típicos em estudos de treinamento resistido. A experiência dos avaliadores e o cuidado metodológico com as medidas repetidas foram necessários para observar baixos erros de medida.

Atividade física para adultos: Guia de Atividade Física para a População Brasileira / Physical activity for adults: Physical Activity Guidelines for the Brazilian Population

Em 2020, o Ministério da Saúde, em parceria com a Universidade Federal de Pelotas, Rio Grande do Sul, selecionou pesquisadores e pesquisadoras para a elaboração do Guia de Atividade Física para a População Brasileira. O objetivo deste artigo foi apresentar os métodos utilizados, bem como os re-sultados do Guia de Atividade Física para a População Brasileira (Guia) para adultos de 18 a 59 anos de idade. A base para construção do Guia se deu a partir de quatro perguntas norteadoras: O quê, quando, por que e como praticar atividade física (AF)? Para responder essas questões, duas estratégias principais foram adotadas: revisão das evidências científicas e a "escuta" de diferentes grupos estra-tégicos. A partir dos procedimentos realizados, recomenda-se que os adultos acumulem entre 150 e 300 minutos de AF por semana com intensidade moderada e/ou entre 75 e 150 minutos por semana de intensidade vigorosa. Dentre os benefícios identificados, destaca-se a redução de mortalidade por doenças crônicas, melhoria na saúde mental, nos aspectos sociais (e.g. interação com outras pessoas, contato com a cultura local etc.) e emocionais (e.g. autoestima, sensação de bem-estar etc.). Além disso, as recomendações não ficaram restritas aos desfechos supracitados, buscou-se considerar as especificidades e singularidades da população adulta nas diferentes regiões do Brasil, destacando que a AF está envolvida em movimentos populares, sociais e culturais. No Guia também são apresentadas mensagens para superar as principais barreiras da AF, e as redes de apoio existentes para auxiliar a população adulta a ter uma vida fisicamente mais ativa

In 2020, the Brazilian Health Ministry in partnership with the Federal University of Pelotas, Rio Grande do Sul selected researchers for the elaboration of the Brazilian Physical Activity Guide. The objective of this article was to present the methods used as well as the results of the Brazilian Physical Activity Guide for adults from 18 to 59 years of age. The construction of the guide was based on four guiding questions: What, when, why and how to practice physical activity? To answer these questions, two main strategies were adopted: review of scientific evidence and "listening" to different strategic groups. From the procedures performed, it is recommended that adults accumulate between 150 and 300 minutes of physical activity per week of moderate intensity and / or between 75 and 150 minutes per week of vigorous intensity, regardless of the type (aerobics or muscle strengthening). Among the identified benefits, the reduction of mortality due to chronic diseases, improvement in mental health, in social and emotional aspects stands out, (e.g., interaction with other people, contact with local culture etc.) and emotional (e.g., self-esteem, feeling of well-being etc.). In addition, the recommendations were not restricted to the aforementioned outcomes, we sought to consider the specificities and singularities of the adult population in different regions of Brazil. The guide also pre-sents messages to overcome the main barriers of physical activity, and the existing support networks to help Brazilian adults to have a more physically active life

Assessment methods of vastus lateralis muscle architecture using panoramic ultrasound: a new approach, test-retest reliability and measurement error / Métodos de avaliação da arquitetura do músculo vasto lateral usando ultrassonografia panorâmica: nova abordagem, confiabilidade teste-reteste e erro da medida

Abstract Extended-field-of-view ultrasonography is a valid alternative to determine the dimensions of the skeletal striated muscle; however, some factors may influence the final measurement. The aim of this study was to determine the test-retest reliability and measurement error of vastus lateralis muscle architecture variables through internal anatomical landmarks and to compare three fixed determined points using extended-field-of-view ultrasonography. Twelve young (24 ± 6 years) adult university male students participated in the study. Images were obtained through extended-field-of-view ultrasonography of the vastus lateralis muscle. Measurements were made for muscle thickness (MT), fascicle length (FL), and fascicle pennation angle (FA) using a method that identifies internal anatomical landmarks. MT was also measured at predetermined distances of 2 cm proximal, 6 cm proximal, and 2 cm distal. One-way ANOVA with repeated measures did not identify any test-retest significant differences for all variables measured. Typical measurement error in centimeters (cm) or degrees (º), coefficient of variation in percentage (%) and intraclass correlation coefficient were MT = 0.07 cm, 2.93%, 0.964; FL = 0.31 cm, 2.89%, 0.947; FA = 0.92°, 4.08%, 0.942; MT 2 cm proximal = 0.10 cm, 3.77%, 0.910; MT 6 cm proximal = 0.27 cm, 9.66%, 0.576; MT 2 cm distal = 0.35 cm, 19.76%, 0.564. MT, FL and FA showed high reliability and low measurement error. Internal anatomical landmarks proved to be more reliable and presented smaller measurement errors when compared to the predetermined distances method.

Resumo A ultrassonografia panorâmica é uma alternativa válida para determinar as dimensões da musculatura estriada esquelética, entretanto alguns fatores podem influenciar a medida final. Objetivou-se determinar a confiabilidade e o erro da medida das variáveis da arquitetura do músculo vasto lateral através de marcações anatômicas internas, bem como comparar dois métodos de avaliação diferentes através da ultrassonografia panorâmica. Doze homens (idade: 24 ± 6 anos) participaram do estudo. As imagens foram obtidas através da ultrassonografia panorâmica do músculo vasto lateral. Foram realizadas as medidas da espessura muscular (EM), comprimento do fascículo (CF) e ângulo de penação do fascículo (AP) através do método que identifica marcações anatômicas internas. A EM também foi medida através de distâncias predeterminadas de 2 cm proximal, 6 cm proximal e 2 cm distal. A ANOVA de uma via com medidas repetidas não identificou diferença significativa para todas as variáveis mensuradas, o erro típico de medida em centímetros (cm) ou graus (º), o coeficiente de variação em percentual (%) e o coeficiente de correlação intraclasse foram respectivamente: EM = 0,07 cm, 2,93%, 0,964; CF = 0,31 cm, 2,89%, 0,947; AP = 0,92º; 4,08%; 0,942; EM 2 cm proximal = 0,10 cm, 3,77%, 0,910; EM 6 cm proximal = 0,27 cm, 9,66%, 0,576; EM 2 cm distal = 0,35 cm, 19,76%, 0,564. EM, CF e AP apresentaram alta confiabilidade e baixo erro de medida. As marcações anatômicas internas demonstraram ser mais confiáveis e apresentam menores erros de medida quando comparados ao método de distâncias predeterminadas.

Acute Effects of L-Arginine Supplementation on Oxygen Consumption Kinetics and Muscle Oxyhemoglobin and Deoxyhemoglobin during Treadmill Running in Male Adults.

L-arginine is used as a nitric oxide related supplement intended to improve sports performance, and to enhance muscular recovery during exercise. However, the literature is inconclusive. The aim of this study was to determine the effects of acute oral L-arginine supplementation on O2 consumption kinetics and local muscle blood volume and oxygenation during treadmill running at two different intensities. Using a double-blind, crossover and placebo-controlled design, 11 young healthy male adults were randomly assigned to 6 g of L-arginine (ARG) or placebo (PLA) supplementation that was ingested 60 min before the exercise test. Tests consisted of treadmill run at two different intensities (5 min each; moderate, 90% of ventilatory threshold, VT; and heavy, 50% of the difference between VT and VO2peak) interspersed by 1-min walking. Respiratory gas exchange variables were measured continuously with an automated metabolic cart. Near infrared spectroscopy (NIRS) was used to continuously monitor muscle oxyhemoglobin and deoxyhemoglobin and total hemoglobin. Blood samples were collected before supplementation and 6 min after exercise. Two-way repeated measures ANOVA did not show differences in plasma nitrite concentrations between ARG or PLA conditions during the running tests. No significant differences were observed between ARG and PLA conditions for O2 kinetics as well as for NIRS variables. ARG supplementation does not improve physiological responses associated with oxygen cost and NIRS variables during running treadmill tests. Hence, our results do not support the use of L-arginine as an ergogenic aid for running performance in young healthy males.

Acute effects of passive static stretching on the vastus lateralis muscle architecture of healthy young men / Efeitos agudos do alongamento estático passivo sobre a arquitetura muscular do vasto lateral de jovens saudáveis

Abstract The aim of the study was to investigate the acute effects of passive static stretching (PSS) on the fascicle length (FL) and fascicle angle (FA) of the vastus lateralis muscle (VL) in two different joint positions. Twelve physically active men (26.9 ± 7.5 years, 178.6 ± 7.0 cm, and 82.5 ± 16.8 kg) were placed in the prone position for the acquisition of ultrasound images (US) of VL, registered with extended and totally flexed knee up to the heel contact with the gluteus, before and after a PSS routine comprised of three 30-s repetitions maintained in the maximal discomfort position as reported by the participant. Results of the paired t-test indicated an increase in FL (16.2%; p = 0.012) and reduction in FA (15.5%; p = 0.003) in pre vs. post stretching comparisons for the extended knee position. There was also a significant increase in FL (34%; p = 0.0001) and reduction in FA (25%; p = 0.0007) when compared the extended knee vs. flexed knee positions. There were no significant differences in muscle architecture variables for the flexed knee position. The results showed high and moderate correlation of FL and FA for the extended (r = -0.89 and r = -0.74) and flexed knee (r = -0.76 and r = -0.78) position, pre and post stretching, respectively. It was concluded that the static stretching acutely affects the vastus lateralis muscle architecture only in the extended knee position, but not in the flexed knee position.

Resumo O objetivo do estudo foi verificar os efeitos agudos do alongamento estático passivo (AEP) sobre o comprimento (CF) e ângulo do fascículo (AF) do músculo vasto lateral (VL) em duas diferentes posições articulares. Doze homens (26,9 ± 7,5 anos; 178,6 ± 7,0 cm; e 82,5 ± 16,8 kg), fisicamente ativos foram posicionados em decúbito ventral para aquisição de imagens de ultrassonografia (US) do VL, registradas com joelho estendido e totalmente flexionado, até o conato do calcanhar com o glúteo, antes e após uma rotina de AEP composta por três repetições de 30 s com manutenção da posição no limite de desconforto relatado pelo participante. O teste t de Student para amostras pareadas indicou aumento no CF (16,2%; p = 0,012) e redução no AF (15,5%; p = 0,003) nas comparações pré vs. após alongamento na posição com o joelho estendido. Também houve aumento significativo do CF (34%; p = 0,0001) e redução do AF (25%; p = 0,0007) na comparação entre as posições de joelho estendido vs. flexionado. Não foram encontradas diferenças significativas nas variáveis da arquitetura muscular investigadas na posição com o joelho flexionado. Os resultados apontaram para correlação alta e moderada do CF e AF com joelho estendido (r = -0,89 e r = -0,74) e joelho flexionado (r = -0,76 e r = -0,78), pré e após alongamento, respectivamente. Concluiu-se que o alongamento estático afeta de forma aguda a arquitetura muscular do vasto lateral apenas na posição de joelho estendido, mas não na posição com joelho flexionado.

Combined effects of resistance training and carbohydrate-restrictive or conventional diets on weight loss, blood variables and endothelium function / Efeitos combinados do treinamento contrarresistência e dietas restritivas em carboidrato ou convencional na perda de peso, variáveis sanguíneas e função endotelial

ABSTRACT Objective: To compare the effects of either a carbohydrate-restrictive diets or a conventional hypoenergetic diet combined with resistance training. Methods: Twenty-one overweight and obese adults participated in an eight-week program consisting of progressive resistance training combined with carbohydrate-restrictive diets (initially set at <30 g carbohydrate; n=12) or conventional hypoenergetic diet (30% energetic restriction; carbohydrate/protein/lipid: 51/18/31% of total energy consumption; n=9). It was hypothesized that the carbohydrate-restrictive diets would induce greater weight loss but that both diets would elicit similar effects on selected health markers. Body mass, and body composition, blood variables and flow-mediated brachial artery dilation (flow-mediated brachial artery dilation; by ultrasound) were used to assess changes due to the interventions. Results: Significant within-group reductions in body mass (-5.4±3.5%; p=0.001 versus -3.7±3.0%; p=0.015) and body fat (body fat; -10.2±7.0%; p=0.005 versus -9.6±8.8%; p=0.017) were identified for carbohydrate-restrictive diets and conventional hypoenergetic diet, respectively, but there were no significant differences between groups as the result of the interventions. Fat free mass, blood variables and flow-mediated brachial artery dilation did not significantly change, except for the total cholesterol/high-density lipoprotein ratio, which was reduced 10.4±16.9% in carbohydrate-restrictive diets (p=0.037) and 0.5±11.3% in conventional hypoenergetic diet (p=0.398). Conclusion: Carbohydrate-restrictive diets associated with resistance training was as effective as conventional hypoenergetic diet in decreasing body mass and body fat, as well as maintaining fat free mass, blood variables and flow-mediated brachial artery dilation, however it was more effective at lowering the total cholesterol/low density lipoprotein ratio.

RESUMO Objetivo: Comparar os efeitos entre a dieta com restrição de carboidratos e a dieta hipoenergética convencional combinadas com treinamento contrarresistência. Trabalhou-se com a hipótese de que as dietas com restrição em carboidratos poderiam acarretar maior perda de peso, mas que, no entanto, ambas causariam efeitos similares nos biomarcadores de saúde. Métodos: Vinte e um adultos com sobrepeso ou obesos participaram de um programa de 8 semanas de treinamento contrarresistência progressive combinado com dieta com restrição de carboidratos (inicialmente com <30 g de carboidrato; n=12) ou com dieta hipoenergética convencional (30% de restrição energética; carboidrato/proteína/lipídeos: 51/18/31% do valor energético total; n=9). Massa e composição corporais, variáveis sanguíneas (glicose, ureia, creatinina, ácido úrico, lipemia sanguínea, proteína creativa de alta sensibilidade) e dilatação fluxo-mediada da artéria braquial (por ultrassom) foram acompanhadas para observar os efeitos das intervenções. Resultados: Foram identificadas reduções significativas na massa corporal (-5,4±3,5%; p=0,001 versus -3,7±3,0%; p=0,015) e na gordura corporal (-10,2±7,0%; p=0,005 versus -9,6±8,8%; p=0,017) de indivíduos em dieta com restrição de carboidratos e dieta hipoenergética convencional, respectivamente, sem diferenças significativas entre os grupos. Massa livre de gordura, variáveis sanguíneas e dilatação fluxo-mediada da artéria braquial não sofreram modificações significativas, exceto a razão colesterol total/lipoproteína de alta densidade, que reduziu 10,4±16,9% em dietas com restrição de carboidratos (p=0,037) e 0,5±11,3% em dieta hipoenergética convencional (p=0,398). Conclusão: A dieta com restrição de carboidratos associada ao treinamento contrarresistência foi tão efetiva quanto a dieta convencional em reduzir a massa e a gordura corporais, assim como em manter os valores da massa livre de gordura, das variáveis sanguíneas e da dilatação fluxo-mediada da artéria braquial. No entanto, foi mais efetiva na redução da razão colesterol total/lipoproteína de baixa densidade.

EFEITO AGUDO DE DIFERENTES ROTINAS DE ALONGAMENTO ESTÁTICO SOBRE O SALTO COM CONTRAMOVIMENTO / ACUTE EFFECT OF DIFFERENT STATIC STRETCHING ROUTINES ON COUNTERMOVEMENT JUMP

RESUMOO objetivo foi observar o efeito de duas rotinas de alongamento estático com mesmo volume, sobre amplitude de movimento (ADM) de flexão (FJ) e extensão de joelho (EJ) e sobre a altura do salto com contramovimento. Dez voluntários do sexo masculino foram submetidos aleatoriamente às rotinas de alongamento fracionado (AL-10), com 3 séries de 10 s, alongamento contínuo (AL-30), com uma única série de 30 s e à uma condição controle (CC). A altura do salto foi obtida imediatamente após as intervenções através de um tapete de contato. A ADM foi medida através da fotogrametria pré e após intervenção. Uma ANOVA de medidas repetidas seguida pelo teste post hoc de Bonferroni identificou um aumento significativo na ADM na FJ (P=0,004) e EJ (P=0,001) após AL-30 e aumento significativo na altura do salto após AL-10 comparados à CC (P=0,005). Conclui-se que uma rotina contínua de 30 s de alongamento estático aumentam a ADM sem prejuízo no desempenho, enquanto rotinas fracionadas, com 3 séries de 10 s não alteram a ADM, entretanto melhoram a altura do salto.

ABSTRACTThe aim of the study was to observe the effects of two stretching routines, with the same total volume, on countermovement jump height (JH) and range of motion (ROM) of knee flexion (KF) and extension (KE). Ten subjects were randomly assigned to either a fractionated stretching (ST-10) with 3 sets of 10 s, or continuous routine (ST-30), with a single 30 s set, and a non-experimental control condition (CC). The JH was obtained immediately after interventions using a contact matt. ROM was measured by photogrammetry pre and post intervention. A repeated measures ANOVA followed by Bonferroni's post hoc test showed a significant increase in KF (P=0.004) and KE (P=0.001) ROM post ST-30 and a significant JH increase after ST-10 compared to CC (P=0.005). It was concluded that continuous static stretching routines may increase ROM without altering JH, while the fractionated routine with the same volume, may not alter ROM although improving JH.

O alongamento estático aumenta a amplitude de movimento sem prejudicar o desempenho de saltos verticais sucessivos / Static stretching enhances range of motion without interfering with successive vertical jumps

O objetivo foi verificar o efeito agudo de 2x30s de alongamento estático na musculatura posterior de membros inferiores sobre a amplitude de movimento (ADM) e altura do salto com contra movimento. Doze voluntários foram submetidos aleatoriamente às condições de alongamento e controle em ocasiões diferentes. A altura do salto foi obtida por meio de um tapete de contato, imediatamente após 3, 6 e 9 min depois de cada condição. A ADM foi medida pelo método de fotogrametria realizada antes, imediatamente e 9 min após cada condição. A ANOVA a dois caminhos com medidas repetidas não encontrou diferença significativa na altura do salto em qualquer dos momentos testados. Entretanto, o teste post hoc de Bonferroni mostrou aumento significativo na ADM apenas imediatamente após a realização do alongamento. Concluiu-se que rotinas reduzidas de alongamento estático não interferem no desempenho do salto, além de aumentarem significativamente de forma aguda a ADM.

The purpose of the study was to observe the acute effect of static stretching of lower limbs muscles on the range of motion (ROM) and on the countermovement jump performance. Twelve adult males were randomly subjected to a stretching and a non-stretching condition on separate occasions. Jump height was determined using an electronic contact mat after jumps performed immediately post and 3, 6 and 9 min after either stretching or control conditions. The ROM was determined by digital photogrammetry method at pre, immediately post and 9 min after different conditions. A two-way ANOVA with repeated measures evidenced no significant differences in jump height for all time measurements. Nevertheless, Bonferroni post-hoc test showed a significant increase in ROM only immediately after the stretching routine. It was concluded that a short volume of static stretching does not impair the jump performance, although it has a sufficient magnitude to significantly improve the ROM in an acute form.

The effects of rest intervals on jumping performance: a meta-analysis on post-activation potentiation studies.

The purpose of this meta-analytic review was to examine the extent and quality of research on the post-activation potentiation acute effect of rest interval manipulation on jumping performance. This manuscript adopted the recommendations from the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement. Criteria eligibility included crossover, randomised, non-randomised and counterbalanced studies that observed the voluntary muscle action-induced post-activation potentiation on jumping performance. Fourteen studies selected by two independent raters were included in the analysis. The rest intervals involved ranges including 0-3, 4-7, 8-12 and ≥16 min. The results demonstrated medium effect sizes for rest intervals 0-3 and 8-12 min (-0.25, confidence interval (CI): -0.51 to 0.01 for 0-3 min; 0.24, CI: -0.02 to 0.49 for 8-12 min) and a small effect for other ranges (0.15, CI: -0.08 to 0.38 for 4-7 min; 0.07, CI: -0.21 to 0.24 for ≥16 min). There was no evidence of heterogeneity for sub-groups (I2 = 0%; P < 0.001) and no indication of publication bias (Egger's test, P = 0.179). While a rest interval of 0-3 min induced a detrimental effect on jump performance, the range including 8-12 min had a beneficial impact on jump height. Findings suggest that the rest interval manipulation seems to affect post-activation potentiation magnitude and jump height.

Effects of hypoxia on cerebral and muscle haemodynamics during knee extensions in healthy subjects.

A hypoxic model was used to investigate changes in localized cerebral and muscle haemodynamics during knee extension (KE) in healthy individuals. Thirty-one young healthy volunteers performed one set of KE until failure under hypoxia (14 % O(2)) or normoxia (21 % O(2)) at 50, 75 or 100 % of 1 repetition maximum, in random order, on three occasions. Prefrontal cerebral and vastus lateralis muscle oxygenation and blood volume (Cox, Mox, Cbv and Mbv, respectively) were recorded simultaneously by near-infrared spectroscopy. Hypoxia induced significant declines in Cox [-0.017 ± 0.016 optical density (OD) units] and Mox (-0.014 ± 0.026 OD units) and increases in Cbv (0.017 ± 0.027 OD units) and Mbv (0.016 ± 0.023 OD units) at rest. Hypoxia significantly reduced total work (TW) performed during KE at each exercise intensity. Cox, Cbv, Mox, and Mbv changes during KE did not differ between normoxia and hypoxia. Correlations between TW done and Cox changes under normoxia (r = 0.04, p = 0.182) and hypoxia (r = 0.05, p = 0.122) were not significant. However, TW was significantly correlated with Mox under both normoxia (R (2) = 0.24, p = 0.000) and hypoxia (R (2) = 0.15, p = 0.004). Since changes in Cox and Mox reflect alterations in the balance between oxygen delivery and extraction in these tissues, which, in the brain, is an index of neuronal activation, we conclude that: (1) limitation of KE performance was mediated peripherally under both normoxia and hypoxia, with no additional effect of hypoxia, and (2) because of the low common variance with Mox additional intramuscular factors likely play a role in limiting KE performance.

Does vibration counteract the static stretch-induced deficit on muscle force development?

OBJECTIVES: To determine the residual acute vibration-stretching effect on preactivation levels, short-latency stretch reflex, and performance during execution of drop jumps. DESIGN: Repeated measures. METHODS: Eleven male recreational athletes performed a set of three 45cm drop jumps before and immediately after a 30s static stretching exercise with and without simultaneously imposed muscle vibration (45Hz, 5mm). Drop jump height, ground reaction forces and electromyographic data including Vastus Lateralis onset/levels of preactivation and short-latency stretch reflex were recorded. RESULTS: No changes were induced on drop jump height. However, stretching-induced decrements on ground reaction force peak and time to peak as well as an increment in contact time followed a delay in short-latency stretch reflex onset and a reduced preactivation level of Vastus Lateralis. Otherwise, when vibration was simultaneously imposed, there was no evidence of changes in high-speed force production variables or electromyographic recordings. CONCLUSIONS: Mechanical vibration, when applied simultaneously to static-stretching routines, appeared to be effective to counteract decreased musculotendinous unit stiffness-induced high-speed force production deficit during jumping performance.

Does whole-body vibration acutely improve power performance via increased short latency stretch reflex response?

OBJECTIVES: It remains unclear whether an increased intrafusal mechanical sensitivity is related to the vibration-induced performance improvement. This investigation aimed to determine the residual acute effect of whole-body vibration and its duration on pre-activation levels, short-latency stretch reflex and performance during drop jumps. DESIGN: Repeated measures. METHODS: Eleven amateur athletes performed a set of three 45cm-drop jumps before and during a 20min-interval following three randomized conditions: No, Low (30Hz, 5mm) and High vibration (45Hz, 5mm). Ground reaction force peak, Soleus and Vastus Lateralis short latency stretch reflex onset and amplitude were assessed during drop jumps. RESULTS: A significant effect for time revealed an immediate drop jump height increase after High vibration. A longer contact time also followed High vibration while no changes were detected after Low vibration. Vibration did not affect ground reaction force peak and short latency stretch reflex component. CONCLUSIONS: High vibration constituted an intervention for improving performance although there was no evidence of increased stretch reflex responses.

Confiabilidade intra-avaliador da medida de amplitude de movimento da flexão e extensão do joelho pelo método de fotogrametria / Intra-rater reliability of knee flexion and extension range of motion measurement through the photogrammetry method

Apesar de existirem diversos métodos para a determinação da amplitude de movimento (ADM), a baixa confiabilidade, a pouca sensibilidade, a subjetividade ou a ausência de valores do erro típico da medida (ETM) de alguns desses métodos comprometem a interpretação adequada dos resultados. O objetivo deste estudo foi determinar a confiabilidade intra-avaliador da medida e do método de fotogrametria para a ADM de extensão ativa e flexão passiva do joelho (FPJ), realizada no mesmo dia (consistência interna) e em dias diferentes (estabilidade). Participaram 18 sujeitos do sexo masculino (24,5±3,7 anos, 79,3±10,1 kg e 174,8±4,2 cm). Após a marcação dos pontos anatômicos de referência, a angulação dos movimentos foi registrada em fotografia, por meio da ferramenta de dimensão angular no software CorelDRAW®. A confiabilidade da medida e do instrumento foi estabelecida pelo coeficiente de correlação intraclasse (CCI) e pelo cálculo do ETM. A distribuição dos erros dos dados foi verificada pela representação gráfica de Bland e Altman. O método apresentou confiabilidade perfeita (ETM=0,01 e CCI=1,0) para ambos os movimentos. Para a confiabilidade da medida, foram encontrados os valores 0,97 e 0,93 para consistência interna e 0,96 e 0,83 para estabilidade (ETM=2,9 e 4,0%; p<0,001) na extensão e flexão do joelho, respectivamente. O método mostrou excelente confiabilidade e baixo erro na determinação da ADM de extensão e flexão do joelho, sendo assim, adequado para a aplicação em dimensão clínica e de pesquisa.

Although there are several methods for determining the range of motion (ROM), low reliability, low sensitivity, subjectivity or lack of information related to the typical error of measurement (TEM) may compromise interpretation of testing results. The aim of this study was to test the intra-rater reliability of the ROM measurement and the photogrammetry method for same day (internal consistency) and between days (stability) for knee active extension and passive flexion. Eighteen active male volunteers (24.5±3.7 years, 79.3±10.1 kg and 174.8±4.2 cm) were selected to participate in the study. After identification of anatomical landmarks used for reference, knee passive flexion and active extension were recorded by photography and then analyzed using an angular dimension tool from CorelDRAW®. The reliability of the measurement and the instrument was determined using intraclass correlation coefficient (ICC) and TEM. Data distribution was observed using the graphical representation of Bland e Altman. The method showed a perfect reliability (TEM=0.01 and ICC=1.0) for both extension and flexion movements. The measurement showed high reliability 0.97 and 0.93 (internal consistency) and 0.96 and 0.83 (stability) (TEM=2.9 and 4.0%, p<0.001) for knee extension and flexion, respectively. The method showed to be very reliable with a low typical error of the measurement knee extension and flexion ROM, showing to be adequate for application in both, clinical and research settings.

Acute l-arginine supplementation increases muscle blood volume but not strength performance.

l-Arginine (L-arg) is an amino acid precursor to nitric oxide (NO). Dietary supplements containing L-arg have been marketed with the purpose of increasing vasodilation, thereby elevating blood flow to the exercising muscle and enhancing the metabolic response to exercise. Our goal was to identify the acute effect of L-arg supplementation on biceps strength performance, indicators of NO production (nitrite and nitrate - NOx), and muscle blood volume (Mbv) and oxygenation (Mox) during recovery from 3 sets of resistance exercise. Fifteen males participated in a randomized, double-blind, placebo-controlled study. After withdrawing resting blood samples, the subjects were supplemented with 6 g of L-arg (ARG) or placebo (PLA). Monitoring of Mbv and Mox with near-infrared spectroscopy began 30 min after supplementation and lasted for 60 min. The exercise protocol (3 sets of 10 maximal voluntary contractions of isokinetic concentric elbow extension at 60°·s(-1), 2-min rest between sets) was initiated 80 min after supplementation. Blood samples were drawn at 30, 60, 90, and 120 min after supplementation. Repeated measures ANOVA showed that Mbv significantly (p ≤ 0.05) increased in ARG compared with the PLA during the recovery period of each set of resistance exercise. NOx, Mox, peak torque, total work, and set total work were not significantly different between groups. We found that acute L-arg supplementation increases Mbv during recovery from sets of resistance exercise with no increase in strength performance. It is still premature to recommend nutritional supplements containing L-arg as an ergogenic aid to increase muscle strength during resistance training in healthy subjects.

Efeitos da desidratação sobre desempenho de força de atletas de jiu-jitsu / Effects of dehydration on strength performance of Brazilian Jiu-jitsu fighters

Estratégias destinadas a rápida e drástica redução de peso são comumente adotadas por atletas que competem em eventos de combate esportivo. Portanto, o objetivo do estudo foi determinar o efeito agudo da desidratação induzida por sauna sobre a força e a resistência muscular de atletas de Jiu-jitsu. Onze atletas foram submetidos a um teste de força dinâmica máxima (1RM) no Leg Press nas condições de euhidratação (EH) e desidratação (DES – ~2% do peso) induzida por sauna seca. Em um protocolo adicional, seis voluntários dos onze iniciais também foram submetidos a um teste de resistência muscular localizada (número máximo de repetições com 60% de 1RM no exercício supino reto) e a análise de amostragem sanguínea em ambas as condições (EH e DES). A redução na massa corporal de aproximadamente 2,1% não induziu efeito deletério significativo sobre a força dinâmica máxima (EH 307,72 ± 87,7 kg vs. DES 306,27 ± 88,3 kg; P = 0,148) e a resistência muscular localizada (EH = 29 ± 4 repetições; DES = 28 ± 4 repetições; P= 0,180). Embora a desidratação tenha causado uma redução de 7,6 ± 1,5% no volume plasmático, a concentração de bicarbonato sanguíneo não mudou significativamente (27,2 ± 7,5 vs. 27,5 ± 7,2 mEq/L, condições EH e DES, respectivamente). Concluindo, a desidratação moderada induzida por sauna não afetou significativamente a força e a resistência muscular, além de não induzir alterações nas variáveis bioquímicas associadas ao desempenho de endurance.

Athletes who compete in combat sports events commonly adopt strategies aimed to a fast and drastic weight loss. Therefore, the purpose of this study was to determine the acute effect of sauna- induced dehydration on strength and endurance performance of Brazilian Jiu-jitsu athletes. Eleven athletes performed a one-repetition maximum test (1RM) on a Leg Press exercise in two different hydration states, euhydration (EH) and dry sauna-induced dehydration (DES - 2% of body mass). Additionally, six of the eleven athletes were also submitted to a muscle endurance test (the maximum number of repetitions at 60% of 1RM on a bench press exercise). Blood samples were withdrawn from the same subsample in both hydration conditions. An approximate body mass reduction of 2.1% did not induce a significant deleterious effect on either muscular strength (EH 307.72 ± 87.7 kg vs. DES 306.27 ± 88.3 kg; P = 0.148) or endurance (EH = 29 ± 4 repetitions; DES = 28 ± 4 repetition; P = 0.180). Although dehydration has induced a plasma volume reduction of 7.6 + 1%, plasmatic bicarbonate concentration did not change (EH = 27.2 ± 7.5 vs. DES = 27.5 ± 7.2 mEq/L for EH and DES, respectively). In conclusion, sauna-induced moderate dehydration did not significantly affect either muscular strength or endurance. In addition, no changes were induced on biochemical variables related to the endurance performance.

Confiabilidade da medida de espessuras musculares pela ultrassonografia / Reliability of muscle thickness measurements using ultrasound

OBJETIVO: Determinar a confiabilidade das medidas de espessuras dos músculos flexores e extensores do cotovelo e joelho pela ultrassonografia (US), quantificando o erro típico associado a essas medidas (ETM). MÉTODOS: A confiabilidade (duas medidas interdias) foi determinada em 15 voluntários aparentemente saudáveis (oito mulheres, 33,9 ± 11,4 anos, 76 ± 21kg, 170 ± 10cm). As imagens da musculatura flexora (FC) e extensora do cotovelo (EC) e flexora (FJ) e extensora do joelho (EJ) foram obtidas pela US bidimensional no modo B, utilizando transdutor de 7,5MHz. As espessuras do tecido muscular compreendidas entre as interfaces com o osso e com o tecido adiposo foram medidas em sítios anatômicos identificados e registrados para ser repetidos na segunda medida. RESULTADOS: A ANOVA não identificou diferenças significativas entre as medidas repetidas. Os coeficientes de correlação intraclasse foram FC = 0,970, EC = 0,971, FJ = 0,555 e EJ = 0,929 (P < 0,05 para todos). Os coeficientes de variação foram de 3,9 por cento, 6,1 por cento, 6,6 por cento e 4,6 por cento, e os ETM 1,3mm, 1,6mm, 4,9mm e 1,9mm, respectivamente, para espessuras de FC, EC, FJ e EJ. A análise dos gráficos de Bland-Altman apontou que as variáveis não apresentaram erro heterocedástico. CONCLUSÃO: As medidas de espessuras musculares de FC, EC e EJ apresentaram alta confiabilidade, possibilitando seu uso para intervenções como programas de dieta, treinamento físico ou reabilitação. No entanto, o uso da medida de FJ não deve ser recomendada, pois mostrou baixa confiabilidade e alto ETM.

PURPOSE: To determine the reliability of muscle thickness measurements of elbow and knee flexors and extensors using ultrasound, and to quantify the typical error associated to the measurements (TEM). METHODS: The test-retest reliability was determined in 15 apparently healthy volunteers (8 women, 34 ± 11 years, 76 ± 21 kg, 170 ± 10 cm). The images of elbow flexors (EF) and extensors (EE) and knee flexors (KF) and extensors (KE) were obtained using a two dimensional mode B ultrasound instrument with a 7.5 MHz transducer. Muscle thickness between the adipose tissue and bone interfaces were measured at anatomical landmarks previously identified and recorded to assure the exact site for the retest. RESULTS: ANOVA did not identify any significant differences between the repeated measurements. Intraclass correlation coefficients (ICC) of each pair of measure were EF = 0.970, EE = 0.971, KF = 0.555 e KE = 0.929 (P < 0.05 for all). The coefficients of variation were 3.9 percent, 6.1 percent, 6.6 percent e 4.6 percent, and TEM 1.3 mm, 1.6 mm, 4.9 mm e 1.9 mm, respectively, for the EF, EE, KF and KE thickness. Analysis of the Bland-Altman plot charts indicated that the variables did not present heterocedastic errors. CONCLUSION: EF, EE and KE muscle thickness measurements using the current method were highly reliable and can be used to measure and monitor changes in diet, physical training and rehabilitation programs. Nevertheless, KF measure should not be recommended since it presented low reliability and high TEM.

Reliability of brachial artery flow-mediated dilatation measurement using ultrasound.

OBJECTIVE: To determine the reliability of the baseline (BBAB) and post occlusion (POBAD) brachial artery diameters, brachial artery flow-mediated dilatations (BAFMD) measurements, and to quantify the typical error of the measurements (TEM). METHODS: Internal consistency (2 measurements on the same day) was determined in 10 volunteers, whereas stability (2 measurements on separate days) was determined in 13 volunteers. All the volunteers looked healthy and were nonsmokers. The brachial artery images were obtained using a two dimensional Doppler ultrasound instrument: a 14 MHz transducer was used. The distances between the intima-lumen interfaces were measured before and after the blood flow had been stopped by means of a cuff on the arm for five minutes. BAFMD was considered as the percentile increase of POBAD in relation to BBAD. RESULTS: ANOVA did not identify any significant differences between the measurements taken on the same and separate days. For BAFMD, the intraclass correlation coefficients between the measurements taken on the same and separate days were: R = 0.7001 and R = 0.8420, respectively (p < 0.05). The variation coefficients were 5.8% and 12.4% and the relative SMEs were 13.8% and 14.9%, respectively, for the measurements taken on the same and separate days. Analysis of the Bland-Altman graphs indicated that the variables did not present heteroscedastic errors. CONCLUSION: The BBAD, POBAD and BAFMD measurements using the manual ultrasound technique were highly reliable for both the same and separate day measurements and therefore can be used to diagnose and monitor endothelial function.

Número máximo de repetições em exercícios isotônicos: influência da carga, velocidade e intervalo de recuperação entre séries / Maximum number of repetitions in isotonic exercises: influence of load, speed and rest interval between sets

INTRODUÇÃO: Pouco se sabe sobre o efeito da velocidade de execução e do intervalo entre séries sobre o desempenho no exercício contra-resistência. OBJETIVO: Comparar o número máximo de repetições até a fadiga voluntária (REPS) na cadeira extensora com o joelho dominante para diferentes cargas, velocidades e intervalos entre séries. MÉTODOS: Nove voluntários (35,8 ± 10,8 anos; 74,2 ± 16,7kg; 171,0 ± 10,0cm) reportaram ao laboratório para determinação de 1RM e REPS em seis situações, determinadas aleatoriamente e separadas por no mínimo 48h: uma série com 60 por cento 1RM a 80°•s¹ e 25°•s-1; uma série com 80 por cento 1RM a 25°•s¹; três séries com 80 por cento 1RM a 80°•s-1 e intervalos de 3 min, 1 min e naquele que permitisse a estabilização da oxigenação muscular (RMox), medida por espectroscopia no infravermelho próximo. RESULTADOS: O teste t dependente mostrou que REPS foi significativamente (p < 0,05) maior na carga leve que na pesada, nas velocidades lenta (leve = 8,8 ± 1,3; pesada = 5,9 ± 0,9) e rápida (leve = 16,3 ± 3,9; pesada = 9,4 ± 1,9), e significativamente maior na velocidade rápida que na lenta, para ambas as cargas. A ANOVA 3x3 não mostrou diferença entre os intervalos na série 1 (3 min = 9,4 ± 1,9; 1 min = 10,8 ± 3,2; RMox = 10,1 ± 3,0), porém, houve diferenças significativas nas séries 2 e 3 entre 3 min (série 2 = 7,0 ± 1,7; série 3 = 6,4 ± 1,3) e 1 min (série 2 = 5,6 ± 1,1; série 3 = 4,8 ± 1,2), mas não entre RMox (série 2 = 6,4 ± 1,7; série 3 = 6,1 ± 1,5) e os demais intervalos. Nos três intervalos, REPS na série 1 foi significativamente maior que nas demais. CONCLUSÕES: O desempenho no exercício contra-resistência é afetado pela carga, velocidade e intervalo entre séries e é independente da recuperação em oxigenação muscular. A prescrição do exercício e a avaliação do desempenho devem levar...

INTRODUCTION: Very little is known about the effects of movement velocity and rest intervals between sets of resistance exercise. PURPOSE: To compare the maximum number of repetitions to volitional fatigue (REPS) on a knee extension machine with the dominant leg for different loads, velocities and rest intervals between sets. METHODS: Nine volunteers (35.8 ± 10.8 years; 74.2 ± 16.7 kg; 171.0 ± 10.0 cm) reported to the laboratory to determine 1RM and REPS under six conditions, randomly determined and separated by at least 48 h: 1 set with 60 percent 1RM at 80°•s-1 and 25°•s-1; 1 set with 80 percent 1RM at 25°•s-1; 3 sets with 80 percent 1RM at 80°•s-1 and rest intervals of 3 min, 1 min and one that allowed recovery or stabilization of muscle oxygenation (RMox), measured by near infrared spectroscopy (NIRS). RESULTS: Dependent samples t-test showed that REPS was significantly (p < 0.05) larger for the lighter than the heavier load, for slow (light = 8.8 ± 1.3; heavy = 5.9 ± 0.9) and fast velocities (light = 16.3 ± 3.9; heavy = 9.4 ± 1.9), and significantly larger for the fast than the slow velocity, for both loads. The 3x3 ANOVA did not show differences among intervals on set 1 (3 min = 9.4 ± 1.9; 1 min = 10.8 ± 3.2; RMox = 10.1 ± 3.0), however, there were significant differences on sets 2 and 3 between 3 min (set 2 = 7.0 ± 1.7; set 3 = 6.4 ± 1.3) and 1 min (set 2 = 5.6 ± 1.1; set 3 = 4.8 ± 1.2), but not between RMox (set 2 = 6.4 ± 1.7; set 3 = 6.1 ± 1.5) and the other intervals. For all three intervals, REPS on set 1 was significantly larger than on the other sets. CONCLUSIONS: Performance in resistance exercise is affected by load, velocity and rest interval between sets and is independent of muscle oxygenation recovery. Exercise prescription and assessment of performance should take these variables into consideration...

Confiabilidade da medida da dilatação fluxo-mediada da artéria braquial pela ultra-sonografia / Reliability of brachial artery flow-mediated dilatation measurement using ultrasound

OBJETIVO: Determinar a confiabilidade das medidas dos diâmetros basal (DBAB) e pós-oclusão (DPOAB) da artéria braquial e da dilatação fluxo-mediada da artéria braquial (DILA), assim como quantificar o erro típico dessas medidas (ETM). MÉTODOS: A consistência interna (2 medidas intradias) foi determinada em 10 voluntários, enquanto a estabilidade (2 medidas interdias) foi determinada em 13 voluntários aparentemente saudáveis e não-fumantes. As imagens da artéria braquial foram obtidas pelo aparelho de ultra-sonografia bidimensional com Doppler, utilizando transdutor de 14 MHz. As distâncias entre as interfaces íntima-luz foram medidas antes e após interrupção do fluxo sangüíneo durante 5 minutos por manguito posicionado no braço. O DILA foi considerado o porcentual de aumento do DPOAB em relação ao DBAB. RESULTADOS: A ANOVA não identificou diferenças significativas entre as medidas intradias e interdias. Para o DILA, os coeficientes de correlação intraclasse entre as medidas intradias e interdias foram R = 0,7001 e R = 0,8420, respectivamente (p < 0,05). Os coeficientes de variação foram 5,8 por cento e 12,4 por cento e os ETM relativos 13,8 por cento e 14,9 por cento, respectivamente para medidas intra e interdias. A análise dos gráficos de Bland-Altman apontou que as variáveis não apresentaram erro heterocedástico. CONCLUSÃO: A medida do DBAB, DPOAB e do DILA por meio de técnica manual pela ultra-sonografia apresenta alta confiabilidade tanto para os valores intradias quanto interdias, possibilitando seu uso para diagnóstico e monitoramento da função endotelial.

OBJECTIVE: To determine the reliability of the baseline (BBAB) and post occlusion (POBAD) brachial artery diameters, brachial artery flow-mediated dilatations (BAFMD) measurements, and to quantify the typical error of the measurements (TEM). METHODS: Internal consistency (2 measurements on the same day) was determined in 10 volunteers, whereas stability (2 measurements on separate days) was determined in 13 volunteers. All the volunteers looked healthy and were nonsmokers. The brachial artery images were obtained using a two dimensional Doppler ultrasound instrument: a 14 MHz transducer was used. The distances between the intima-lumen interfaces were measured before and after the blood flow had been stopped by means of a cuff on the arm for five minutes. BAFMD was considered as the percentile increase of POBAD in relation to BBAD. RESULTS: ANOVA did not identify any significant differences between the measurements taken on the same and separate days. For BAFMD, the intraclass correlation coefficients between the measurements taken on the same and separate days were: R = 0.7001 and R = 0.8420, respectively (p < 0.05). The variation coefficients were 5.8 percent and 12.4 percent and the relative SMEs were 13.8 percent and 14.9 percent, respectively, for the measurements taken on the same and separate days. Analysis of the Bland-Altman graphs indicated that the variables did not present heteroscedastic errors. CONCLUSION: The BBAD, POBAD and BAFMD measurements using the manual ultrasound technique were highly reliable for both the same and separate day measurements and therefore can be used to diagnose and monitor endothelial function.