OBJECTIVES: Few studies have investigated whether post-exercise hypotension (PEH) after concurrent exercise (CEX) is related to changes in cardiac output (Q) and systemic vascular resistance (SVR) in older individuals. We tested whether PEH after a single bout of CEX circuits performed in open-access facilities at the Third Age Academies (TAA) in Rio de Janeiro City (Brazil) would be concomitant with decreased Q and SVR in individuals aged ≥60 years with prehypertension. Moreover, we assessed autonomic modulation as a potential mechanism underlying PEH. METHODS: Fourteen individuals (age, 65.8±0.9 y; systolic/diastolic blood pressure [SBP/DBP], 132.4±12.1/72.8±10.8 mmHg; with half of the patients taking antihypertensive medications) had their blood pressure (BP), heart rate (HR), Q, SVR, HR variability (HRV), and spontaneous baroreflex sensitivity (BRS) recorded before and 50 min after CEX (40-min circuit, including seven stations of alternate aerobic/resistance exercises at 60-70% HR reserve) and non-exercise control (CONT) sessions. The study protocol was registered in a World Health Organization-accredited office (Trial registration RBR-7BWVPJ). RESULTS: SBP (Δ=−14.2±13.1 mmHg, p=0.0001), DBP (Δ=−5.2±8.2 mmHg, p= 0.04), Q (Δ=−2.2±1.5 L/min, p=0.0001), and BRS (Δ=−3.5±2.6 ms/mmHg; p=0.05) decreased after CEX as compared with the CONT session. By contrast, the HR increased (Δ=9.4±7.2 bpm, p<0.0001), and SVR remained stable throughout the postexercise period as compared with the CONT session (Δ=0.10±0.22 AU, p=0.14). We found no significant difference between the CEX and CONT with respect to the HRV indexes reflecting autonomic modulation. CONCLUSION: CEX induced PEH in the older individuals with prehypertension status. At least in the first 50 min, PEH occurred parallel to the decreased Q and increased HR, while SVR was not different. The changes in autonomic outflow appeared to be unrelated to the acute cardiac and hemodynamic responses.

Resumo Objetivo: Este estudo propôs construir, validar e verificar a confiabilidade de um protocolo de avaliação da capacidade cardiorrespiratória de idosos frequentadores do projeto Rio ao Ar Livre (RAL), denominado “Teste Circuito ao Ar Livre (TCAL) Método: foram realizados testes de validade e confiabilidade para verificar a acurácia do TCAL com 50 idosos (70,6±6,3 anos) de ambos os sexos e frequentadores do RAL. A validade foi testada através de coleta de dados de VO2máx em teste cardiopulmonar de exercício máximo e de variáveis do TCAL: a) Tempo de Execução do Circuito; b) Frequência Cardíaca; c) Percepção Subjetiva de Esforço; d) Frequência Cardíaca Média (FCméd). A confiabilidade foi testada através da reprodutibilidade das medidas das variáveis do TCAL, expressas pelo Coeficiente de Correlação Intraclasse (ICC). A capacidade preditiva do VO2máx deu-se por regressão linear múltipla e a estabilidade final do modelo por análise de resíduos e cálculo das distâncias de Cook, sendo adotado o valor de P≤0,05 para significância estatística. Resultados: O modelo preditivo baseado na idade, sexo, circunferência da cintura, IMC e tempo de execução do circuito explicou 41% da variância do VO2máx, com erro-padrão de estimativa de 18,5%, e apresentou reprodutibilidade de 0,62 a 0,93. Conclusão: O TCAL mostrou-se válido, confiável e específico para predição da aptidão cardiorrespiratória de idosos frequentadores do RAL, mostrando adequada reprodutibilidade e positiva associação com a aptidão física dos idosos.

Abstract Objective: the present study aimed to construct, validate and verify the reliability of a protocol for assessing the cardiorespiratory capacity of older adults attending the Rio ao Ar Livre (Open Air Rio, or RAL) project entitled the “Outdoor Circuit Test” (OCT). Method: validity and reliability tests were carried out to assess the accuracy of the OCT, with 50 older adults (70.6 ± 6.3 years) of both sexes who regularly attended the RAL. Validity was tested by collecting VO2max data under maximal cardiopulmonary exercise test conditions, and the OCT variables: a) Circuit Execution Time; b) Heart Rate; c) Subjective Perception of Exertion; d) Average Heart Rate (HRméd). Reliability was tested through the reproducibility of the measurements of the OCT variables, expressed by the Intraclass Correlation Coefficient (ICC). The predictive capacity of VO2max was given by multiple linear regression and the final stability of the model by the analysis of the residues and the calculation of Cook’s distances, with a value of P≤ 0.05 adopted for statistical significance. Results: the predictive model based on age, sex, waist circumference, BMI and circuit execution time explained 41% of VO2max variance, with a standard error of estimate of 18.5%. Conclusion: the OCT exhibited satisfactory reproducibility (0.62 to 0.93), and proved to be valid, reliable, and specific for predicting the cardiorespiratory fitness of older adults attending RAL, demonstrating adequate reproducibility and a positive association with the physical fitness of older adults.

OBJECTIVES: Physical activity (PA) may reduce cardiovascular risk and preserve functional capacity of people living with human immunodeficiency virus (HIV). However, only limited research objectively measured PA in patients with low socioeconomic status (SES) in low-income countries, particularly in South America and sub-Saharan Africa. This study compared the PA assessed by accelerometers in women of low SES living with HIV under common antiretroviral therapy (cART) from two major cities in Brazil (Rio de Janeiro, n=33; 40.1±6.1 years) and Mozambique (Maputo, n=50; 38.8±8.7 years). METHODS: Eligible women wore triaxial accelerometers during seven consecutive days, to estimate their habitual PA and daily energy expenditure. RESULTS: The proportion of participants with overweight/obesity was greater in Rio than Maputo (57% vs. 30%; p=0.021), as well as those classified as sedentary based on steps/day (45% vs. 22%; p=0.02). Sedentary time was prevalent (Median±IQD: Rio-1236±142 vs. Maputo-1192±135 min/day; p=0.15). Time spent in PA was short, but Brazilians exhibited lower amount of light (111±56 vs. 145±51 min/day; p<0.001) and moderate-to-vigorous PA (88±3 vs. 64±36 min/day; p=0.001) vs. Mozambicans. The proportion of patients performing 60 min/day of moderate-to-vigorous PA were 58% (Rio) and 82% (Maputo), respectively. Despite of this, estimated daily energy expenditure was equivalent in both groups (1976±579 vs. 1933±492 kcal; p=0.731). CONCLUSIONS: Women with low SES living with HIV in Maputo were more active vs. patients from Rio de Janeiro. Albeit sedentary behavior was prevalent, the proportion of patients complying with the minimum recommended PA for health was higher than values usually reported in developed countries.

Resumo: Objetivos: A prevalência da obesidade está aumentando. O objetivo deste estudo foi investigar se há disfunção endotelial nas crianças com peso normal ou excesso de peso e se o perfil metabólico, as adipocinas e a disfunção endotelial seriam mais fortemente associados à aptidão física ou aos níveis de atividade física. Método: Estudo transversal que envolve crianças de 5-12 anos. A avaliação incluiu pletismografia de oclusão venosa, níveis séricos de adiponectina, leptina, insulina e lipidograma, escore de atividade física (questionário PAQ-C) e avaliação da aptidão física (teste Yo-yo). Resultados: Um total de 62 crianças participou deste estudo. Com base no índice de massa corporal, 27 eram eutróficos, 10 estavam acima do peso e 25 estavam obesos. Os níveis de triglicerídeos, colesterol LDL, HOMA-RI e leptina estavam mais elevados nas crianças obesas e com excesso de peso que o grupo de eutróficos (p < 0,01). Os níveis de colesterol HDL e adiponectina estavam mais elevados no grupo de eutróficos em comparação ao grupo de obesos e com excesso de peso (p < 0,01). A vasodilatação mediada pelo fluxo após hiperemia foi maior no grupo de eutróficos em comparação aos indivíduos obesos e com excesso de peso (p < 0,05). Não houve nenhuma diferença nos níveis de atividade física entre os grupos medidos pelo PAQ-C. O teste de ida e volta foi significativamente associado ao colesterol HDL (ró = −0,41; p = 0,01) e essa associação continuou após ajustar o escore z do índice de massa corporal (ró = 0,28; p = 0,03). Conclusão: Este estudo mostrou que a disfunção endotelial já está presente nas crianças obesas, sugeriu uma predisposição à doença aterosclerótica. Além disso, os níveis de colesterol HDL foram correlacionados à aptidão física, independentemente do índice de massa corporal.

Abstract Objectives: The prevalence of obesity is increasing. The aim of this study was to investigate if there is endothelial dysfunction in children with normal or excess weight, and whether the metabolic profile, adipokines, and endothelial dysfunction would be more strongly associated with physical fitness or with physical activity levels. Method: Cross-sectional study involving children aged 5-12 years. The evaluation included venous occlusion plethysmography, serum levels of adiponectin, leptin and insulin, lipid profile, physical activity score (PAQ-C questionnaire), and physical fitness evaluation (Yo-Yo test). Results: A total of 62 children participated in this study. Based on the body mass index, 27 were eutrophic, 10 overweight and 25 obese. Triglycerides, LDL cholesterol, HOMA-IR, and leptin were higher in the obese and excess-weight groups compared to the eutrophic group (p < 0.01). HDL cholesterol and adiponectin levels were higher in the eutrophic group compared to the obese and excess-weight groups (p < 0.01). Flow-mediated vasodilation after hyperemia was higher in the eutrophic group in comparison to obese and excess-weight subjects (p < 0.05). There was no difference in the physical activity levels among groups measured by PAQ-C. The Yo-Yo test was significantly associated with HDL cholesterol (rho = −0.41; p = 0.01), and this association remained after adjusting for body mass index z-score (rho = 0.28; p = 0.03). Conclusion: This study showed that endothelial dysfunction is already present in obese children, suggesting a predisposition to atherosclerotic disease. Moreover, HDL cholesterol levels were correlated with physical fitness, regardless of body mass index.

Resumo O objetivo do presente estudo foi identificar o limiar de frequência cardíaca baseado na cinética da frequência cardíaca durante o exercício máximo graduado em jogadores de futebol. Vinte e seis jogadores de futebol masculino realizaram um teste de exercício máximo (protocolo de Bruce) em uma esteira motorizada. O consumo de oxigênio (VO2) e a freqüência cardíaca (FC) foram monitorados, registrados e reamostrados a 3,5Hz. O limiar ventilatório (LV), a compensação respiratória (CR), os pontos de deflexões da frequência cardíaca (PDFC1 e PDFC2) e o limiar da cinética da frequência cardíaca (LCFC) foram determinados por métodos computadorizados. A variabilidade da frequência cardíaca (VFC) foi avaliada no domínio da frequência. A média do LCFC foi de 89,9 ± 1,2% do VO2 de pico. O LCFC demonstrou correlações e diferenças significativas em relação ao PDFC1 (r = 0,46) e ao LV (r = 0,51), mas não foi diferente e altamente correlacionado com PDFC2 (0,98) e CR (0,90). Os gráficos de Bland Altman mostraram todos os atletas em 95% dos limites de concordância, e o coeficiente de correlação intraclasse apresentou boas concordâncias entre os pontos obtidos com o LCFC em comparação com o PDFC2 (0,96) e CR (0,98). A LCFC foi altamente correlacionada com PDFC2 e CR, sugerindo que poderia ser um marcador de fadiga cardiorrespiratória.

Abstract The main of the present study was to identify the heart rate threshold based on heart rate kinetics during graded maximal exercise in football players. Twenty-six male football players performed a maximal exercise test (Bruce protocol) on a motor-driven treadmill. Oxygen uptake (VO2) and heart rate (HR) were monitored, recorded and resampled at 3.5Hz. The ventilatory threshold (VT), and respiratory compensation (RC), heart rate deflection points (HRDP1 and HRDP2) and heart rate kinetics threshold (HRT) were determined by computerized methods. The heart rate variability (HRV) was assessed in the frequency domain. The HRT averaged 89.9 ± 1.2 % of the VO2 peak. The HRT showed poor correlations and significant differences compared with HRDP1 (r = 0.46) and VT (r = 0.51), but was not different from, and highly correlated with, HRDP2 (0.98) and RC (0.90). Bland Altman plots showed all athletes into 95% of limits of agreement, and intraclass correlation coefficient showed good agreements between points obtained from HRT compared with HRDP2 (0.96) and RC (0.98). The HRT was highly correlated with HRDP2 and RC, suggesting it could be a marker for cardiorespiratory fatigue.

SUMMARY: The purpose of this study was to compare different methods of maturity evaluation and their relation with performance-related physical and anthropometric variables in young soccer players, with different plasma zinc status. A total of 53 healthy male young soccer players (age: 13±1 years; body mass: 48±10 kg; stature: 160±10 cm) participated in this study. Variables from physical fitness (stature, ST; fat-free mass, FFM; handgrip strength in the dominant hand, DHS), testosterone and zinc plasma concentration were measured. Biological maturity was evaluated by sexual maturity (development of: pubic hair, PH; genitals, GD; axillary hair; AH), bone maturity (TW3 method; BA), and testosterone plasma concentration methods. We observed that: (i) the frequency of hypozincemics and normozincemics children stratified by BA-CA, PH and GD were similar in each category; (ii) the BA allowed the identification of differences between the three categories, in at least two performance-related variables (FFM and DHS, p<0.0001); (iii) the AH method was able to discriminate only for DHS (p<0.0001); and (iv) the testosterone method was not able to identify differences between the four maturation categories with regard to ST, FFM, and DHS. Results suggested that Zinc deficiency did not influence the results obtained for the maturation categories defined by the different assessment methods. The assessment of biological maturation by BA seems to be the most effective for the stratification of performance-related and anthropometric variables in young soccer players. Nevertheless, the AH method should also be considered as a fair option to be used in field studies and practice.

RESUMEN: El objetivo de este estudio fue comparar diferentes métodos de evaluación de madurez y su relación con variables físicas y antropométricas relacionadas con el desempeño en jóvenes jugadores de fútbol, con diferentes niveles plasmáticos de zinc. Participaron en este estudio 53 jugadores de fútbol jóvenes sanos (edad: 13 ± 1 años, masa corporal: 48 ± 10 kg, estatura: 160 ± 10 cm). Se midieron las variables de la aptitud física (estatura, ST, masa libre de grasa, FFM, fuerza de agarre en la mano dominante, DHS), testosterona y concentración plasmática de zinc. Se evaluaron la madurez sexual (desarrollo de vello púbico, PH, genitales, DG, cabello axilar, AH), madurez ósea (método TW3, BA) y concentración plasmática de testosterona. Se observó que: (i) la frecuencia de los niños hipoxincémicos y normozincémicos estratificados por BA-CA, PH y GD fueron similares en cada categoría; (ii) el BA permitió la identificación de diferencias entre las tres categorías, en al menos dos variables relacionadas con el desempeño (FFM y DHS, p <0,0001); (iii) el método AH fue capaz de discriminar sólo para DHS (p <0,0001); y (iv) el método de testosterona no fue capaz de identificar diferencias entre las cuatro categorías de maduración con respecto a ST, FFM y DHS. Los resultados sugirieron que la deficiencia de zinc no influyó en los resultados obtenidos para las categorías de maduración definidas por los diferentes métodos de evaluación. La evaluación de la maduración biológica por BA parece ser la más efectiva para la estratificación de variables de rendimiento y antropométricas en jóvenes jugadores de fútbol. Sin embargo, el método AH también debe ser considerado como una opción justa para ser utilizado en estudios de campo y práctica.

Resumo A aptidão cardiorrespiratória (ACR) está associada a vários desfechos de saúde. Algumas equações sem exercício estão disponíveis para estimar a ACR. No entanto, pouco se sabe sobre a validação dessas equações entre os idosos. Objetivo: O estudo foi desenvolvido com o objetivo de examinar a validade de equações sem exercício com informações auto-relatadas em idosos. Métodos: Os participantes (n = 93) com idades entre 60 e 91 anos foram submetidos ao teste de exercício cardiopulmonar máximo para avaliar a ACR. Cinco equações sem exercício foram selecionadas. Os dados incluídos nas equações (idade, sexo, peso, altura, índice de massa corporal, atividade física e tabagismo) foram auto-relatados. Resultados: O coeficiente de determinação (R2) das regressões lineares com o VO2 pico, medido em laboratório, variou de 0,04 a 0,64. Os gráficos de Bland-Altman mostraram maior concordância entre a ACR obtida e prevista por Jackson e colaboradores, e equações de Wier e colaboradores. Por outro lado, as demais equações mostraram menor concordância e superestimação. Conclusões: Nossos resultados fornecem evidências de que duas equações sem exercício, previamente desenvolvidas, poderiam ser usadas na estimação da ACR em idosos.

Abstract Cardiorespiratory fitness (CRF) is associated with several health outcomes. Some non-exercise equations are available for CRF estimation. However, little is known about the validation of these equations among elderly. The aim of this study was to exam the validity of non-exercise equations with self-reported information in elderly. Participants (n= 93) aged 60 to 91 years measured CRF using maximal cardiopulmonary exercise test. Five non-exercise equations were selected. Data included in the equations (age, sex, weight, height, body mass index, physical activity and smoking) were self-reported. Coefficient of determination (R2) of linear regressions with laboratory-measured VO2 peak ranged from 0.04 to 0.64. The Bland-Altman plots showed higher agreement between achieved and predicted CRF obtained by Jackson and colleagues, and Wier and colleagues equations. On the other hand, the other equations showed lower agreement and overestimation. Our findings provide evidences that two non-exercise equations, previously developed, could be used on the prediction of CRF among elderly.

Resumo Introdução: O ângulo de penação (AP) de um músculo não é estático, podendo se adaptar às condições impostas pela contração demandada. Objetivo: Este estudo investigou a influência do ângulo do joelho (AJ) e da intensidade da contração (IC) no AP do vasto lateral (VL). Métodos: Oito mulheres e nove homens executaram torques isométricos durante 5s na contração voluntária máxima (CVM), em 25%, 50% e 75% da CVM, em um equipamento isocinético, com o AJ em 90° e 120° (extensão = 180°). O AP foi medido nos testes e com o sujeito relaxado. O efeito da IC no AP foi testado por ANOVA para medidas repetidas e pelo tamanho do efeito (TE), e o do AJ no AP, por teste t pareado, aplicado a cada IC, junto com as estatísticas: coeficiente de correlação intraclasse (ICC), erro padrão da medida (SEM) e TE, todas calculadas com os APs medidos em ambos AJs. Resultados: O AP aumentou significativamente e sucessivamente com a IC (p < 0,05; TE entre 1,11 e 3,04), mas não foi influenciado pelo AJ (p > 0,05; ICC entre 0,70 e 0,81; SEM entre 0,7° e 1,4°; TE entre 0,02 e 0,20). Conclusão: O aumento sucessivo do AP com a IC corrobora a existência de relação entre estas duas variáveis. Enquanto estudos advogam efeito do ângulo articular no AP, isto não foi observado neste estudo, provavelmente porque a diferença de 30° utilizada entre os AJ não foi suficiente para produzir mudança no AP.

Abstract Introduction: The pennation angle (PA) of a muscle is not static value, but it adapts to the conditions imposed by the contraction intensity required. Objective: This study investigates the effect of knee angle (KA) and intensity of contraction (IC) on PA of vastus lateralis (VL). Methods: Eight women and nine men executed isometric torques lasting 5s at the maximal voluntary contraction (MVC), 25%, 50% and 75% of MVC, on an isokinetic dynamometer with the KA at 90° and 120° (full extension = 180°). The PA was measured in each test, and with the subject relaxed. The effect of IC on PA was tested by means of repeated measures ANOVA and effect size (ES), and of the KA on PA by paired t test, employed on each IC, together with the statistics: intraclass correlation (ICC), standard error of measurement (SEM) and ES, all calculated with the PAs measured at both KAs. Results: The PA increased significantly and successively with the IC (p < 0.05; ES between 1.11 and 3.04), but was not influenced by KA (p > 0.05; ICC between 0.70 and 0.81; SEM between 0.7° and 1.4°; ES between 0.02 and 0.2). Conclusion: The successive increase of PA with the IC supports the existence of relation between these variables. While studies advocate the effect of PA on joint angle this was not observed in this study, probable because the 30o of between KA difference employed was not enough to provide change in PA.

It is feasible to think that the body composition assessment may be influenced by maturational and zinc status, especially in young athletes, which perform regularly high volume of physical training. In accordance, it seems important to clarify the impact of these factors in body composition assessment in athletes, since errors may lead to mistakes in training prescription and diet elaboration, and therefore affect the athletic performance. The objective was to compare (1) different methods of body composition evaluation in young soccer players stratified by zinc plasma levels; and (2) the two reference methods using skinfolds thickness in children (Slaughter's and Lohman's equations), considering the maturation level. In this cross-sectional study, fifty tree young soccer players (13.3±0.7 y) were submitted to blood collection, electric bioimpedance (BIA), dual energy X-ray absorptiometry (DXA), anthropometric measures (body mass, stature and skinfolds thickness (ST)) and hand-wrist X-ray. Body composition evaluation was performed by: DXA, ST (Lohman and Slaughter equations) and BIA (Houtkooper equation) methods. Zinc status provided two groups: Normozincemic and Hypozincemic athletes, determined by cut-off point of 11.0 µmol/L. Significant difference on descriptive data for all participants after zinc status stratification was observed only for plasma zinc concentration; (2) Significant correlations were observed between the assessment methods (fat percentage: r= 0.34 to 0.98 and p<0.001 to 0.013; fat free mass: r= 0.95 to 0.9998 and p<0.001), and lowers correlations were observed when electric impedance was involved; and (3) Bland-Altman plots across methods showed a closer agreement when DXA and ST were compared. In conclusion (1) The ST method was better than BIA to assess the body composition (in young soccer players) when DXA scans are not available; (2) The comparison of models based on ST showed that the best association with the values from DXA were obtained for the Slaughter equation, followed by the Lohman equation using bone age instead of chronological age; and (3) Plasma zinc levels seem not to influence the body composition assessment, which certainly warrants further studies.

Es factible pensar que la evaluación de la composición corporal puede estar influenciada por el estado de maduración y los niveles plasmáticos de zinc, especialmente en atletas jóvenes, que regularmente realizan un alto volumen de entrenamiento físico. Por tanto, es importante aclarar el impacto de estos factores en la evaluación de la composición corporal de los atletas, ya que errores en su análisis pueden conducir al desarrollo de una equivocada prescripción de entrenamiento, además de una dieta determinada, y por lo tanto afectar el rendimiento deportivo. El objetivo de esta investigación consistió en: (1) comparar los diferentes métodos de evaluación de la composición corporal en futbolistas jóvenes estratificados por los niveles plasmáticos de zinc; (2) comparar los dos métodos de referencia utilizando el espesor de los pliegues cutáneos en niños (ecuaciones de Slaughter y Lohman), teniendo en cuenta el nivel de maduración. En este estudio transversal, cincuenta futbolistas jóvenes (13,3±0,7 años) fueron sometidos a un perfil bioquímico de sangre, bioimpedancia eléctrica (BIA), absorciometría de rayos X de energía dual (DXA), medidas antropométricas (masa corporal, estatura y pliegues cutáneos de espesor (ST)) y radiografía de mano-muñeca. La evaluación de la composición corporal se realizó por: DXA, ST (ecuaciones Lohman y Slaughter) y BIA (ecuación Houtkooper). El nivel de zinc identificó dos grupos: deportistas normozincémicos e hipozincémicos, determinados por un punto de corte de 11,0 mmol/L. Se observó una diferencia significativa en los datos descriptivos de todos los participantes después de la estratificación del estado de zinc sólo para la concentración de zinc en plasma; se observaron correlaciones significativas entre los métodos de evaluación (porcentaje de grasa: r= 0,34 a 0,98 y p <0,001 a 0,013; masa libre de grasa: r= desde 0,95 hasta 0,9998 y p <0,001), y disminuyeron las correlaciones al estar involucrada la impedancia eléctrica. Los resultados a través de los métodos Bland y Altman mostraron un acuerdo más cercano al comparar DXA y ST. El método ST fue mejor que el BIA para evaluar la composición corporal (en los jugadores jóvenes de fútbol), cuando no estaban disponibles los escaneos DXA. La comparación de los modelos basados en ST mostró que la mejor asociación de valores DXA se obtuvieron para la ecuación Slaughter, seguidos por la ecuación Lohman utilizando la edad ósea en lugar de la edad cronológica. Los niveles de zinc en plasma parecen no influir en la evaluación de la composición corporal, lo que amerita más estudios.

Resumo Poucos estudos investigaram os efeitos da manipulação das variáveis de prescrição do exercício de alongamento nas respostas cardiovasculares agudas. O objetivo do estudo foi comparar as respostas agudas de frequência cardíaca, pressão arterial e duplo produto, antes, durante e após quatro séries de alongamento estático passivo no movimento de flexão unilateral do quadril. A amostra foi composta por 16 homens com idades entre 18 e 27 anos (22±2,8 anos), sem experiência no treinamento de flexibilidade. Mediu-se as variáveis estudadas por meio de fotopletismografia com registro contínuo cinco minutos em repouso, durante os exercícios e dez minutos após os alongamentos. Todas as variáveis investigadas diferenciaram-se (p<0,05) na situação de repouso e pós-esforço em comparação ao exercício. Somente houve aumento dos valores de pressão arterial entre as séries, sendo a sistólica aumentada da terceira em relação à primeira [série 1= 136 mmHg (±9,4); série 3= 145 mmHg (±9,7)] e a diastólica aumentada da segunda para a primeira [série 1= 79 mmHg (±6,7); série 2= 84 mmHg (±9,1)]. Na situação pós-esforço, não foi verificada hipotensão. Pode-se concluir que as séries de alongamento exibiram efeito cumulativo sobre as respostas de pressão sistólica e diastólica, mas não de frequência cardíaca. No entanto, o protocolo de alongamento não produziu efeito hipotensivo pós-exercício.

Abstract Few studies have investigated the effects of manipulating variables of stretching exercise prescription on acute cardiovascular responses. The objective of this study was to compare the acute responses of heart rate, blood pressure and double product before, during and after four sets of passive static stretching during unilateral hip flexion. The sample consisted of 16 adult men aged 18 to 27 years (22±2.8 years) with no experience in flexibility training. The cardiovascular variables were measured by photoplethysmography with continuous recording for 5 minutes at rest, during exercise and 10 minutes after stretching. A difference was observed in all variables (p<0.05) when resting and post-exercise values were compared to exercise values. There was only an increase in blood pressure values between sets. Systolic blood pressure was increased in the third set compared to the first [set 1 = 136 mmHg (±9.4); set 3 = 145 mmHg (±9.7)] and diastolic blood pressure was increased in the second set compared to the first [set 1 = 79 mmHg (±6.7); set 2 = 84 mmHg (±9.1)]. Hypotension was not observed post-exercise. It was concluded that the stretching sets have a cumulative effect on systolic and diastolic blood pressure responses, but not on heart rate. However, the stretching protocol produced no hypotensive effect after exercise.

A influência da estimulação transcraniana por corrente contínua (ETCC) sobre o desempenho da força muscular em exercícios que recrutam grandes massas musculares ainda não foi estabelecido em populações saudáveis. O objetivo desse estudo foi investigar se a ETCC anódica seria capaz de aumentar o desempenho durante exercício máximo de força (EMF) em sujeitos saudáveis. Catorze voluntários (idade: 26 ± 4 anos) executaram dois EMF com aplicação prévia da ETCC anódica ou placebo (2mA; 20 mim), envolvendo músculos flexores e extensores do joelho dominante em ação concêntrica isocinética (3 séries de 10 repetições). A atividade elétrica muscular (sEMG) de quatro músculos recrutados foi registrada durante o EMF. A ETCC anódica não foi capaz de melhorar a produção de força (trabalho total e pico de torque), resistência à fadiga ou atividade eletromiográfica durante o EMF, quando comparada à condição placebo. Em conclusão, a ETCC anódica aplicada sobre o córtex motor contralateral não foi capaz de aumentar o desempenho de força de flexores e extensores de joelho em jovens saudáveis.

The influence of transcranial direct current stimulation (tDCS) upon maximal strength performance in exercises recruiting large muscle mass has not been established in healthy populations. The purpose of this study was to investigate whether anodal tDCS was able to increase the performance during maximal strength exercise (MSEX) in healthy subjects. Fourteen volunteers (age: 26 ± 4 yrs) performed two MSEX after anodal or sham tDCS (2mA; 20min prior MSEX), involving knee extensors and flexors in concentric isokinetic muscle actions of the dominant limb (3 sets of 10 repetitions). The electrical muscle activity (sEMG) of four recruited muscles was recorded during MSEX. Anodal tDCS was not able to improve force production (i.e., total work and peak torque), fatigue resistance, or electromyographic activity during MSEX when compared to sham condition. In conclusion, anodal tDCS applied upon the contralateral motor cortex was not capable of increasing the strength performance of knee extensors and flexors in young healthy subjects.

La influencia de estimulación transcraneal de corriente directa (tDCS) en ejercicios de fuerza muscular de rendimiento que reclutan grandes masas musculares no se ha establecido en la población sana. El objetivo de este estudio fue investigar si la ETCC anódica podría mejorar el rendimiento durante el ejercicio máximo de la fuerza (EMF) en sujetos sanos. Catorce voluntarios (26 ± 4 años de edad) realizaron dos EMF con la aplicación previa de ETCC anódica y placebo (2 mA, 20 i) la participación de los flexores y extensores de la rodilla dominante en acción concéntrica (3 series de 10 repeticiones). La actividad eléctrica muscular (sEMG) en cuatro músculos reclutados se registró durante el EMF. La ETCC anódica no fue capaz de mejorar la potencia de salida (trabajo total y pico de torque), la resistencia a la fatiga o la actividad electromiográfica durante el EMF, cuando comparada con la condición placebo. Por lo tanto, la ETCC anódica aplicada a la corteza motora contralateral no fue capaz de aumentar el rendimiento de la fuerza de flexores y extensores de la rodilla en jóvenes sanos.

OBJECTIVE: This study investigated the acute hemodynamic responses to multiple sets of passive stretching exercises performed with and without the Valsalva maneuver. METHODS: Fifteen healthy men aged 21 to 29 years with poor flexibility performed stretching protocols comprising 10 sets of maximal passive unilateral hip flexion, sustained for 30 seconds with equal intervals between sets. Protocols without and with the Valsalva maneuver were applied in a random counterbalanced order, separated by 48-hour intervals. Hemodynamic responses were measured by photoplethysmography pre-exercise, during the stretching sets, and post-exercise. RESULTS: The effects of stretching sets on systolic and diastolic blood pressure were cumulative until the fourth set in protocols performed with and without the Valsalva maneuver. The heart rate and rate pressure product increased in both protocols, but no additive effect was observed due to the number of sets. Hemodynamic responses were always higher when stretching was performed with the Valsalva maneuver, causing an additional elevation in the rate pressure product. CONCLUSIONS: Multiple sets of unilateral hip flexion stretching significantly increased blood pressure, heart rate, and rate pressure product values. A cumulative effect of the number of sets occurred only for systolic and diastolic blood pressure, at least in the initial sets of the stretching protocols. The performance of the Valsalva maneuver intensified all hemodynamic responses, which resulted in significant increases in cardiac work during stretching exercises.

Introdução A dependência entre a produção de força isométrica do músculo esquelético e o histórico da contração precedente vem sendo objeto de estudo nos últimos cem anos. Diversas teorias têm sido formuladas para explicar e estabelecer as causas do fenômeno, obtendo pouco sucesso, uma vez que não foram completamente aceitas e comprovadas, suscitando ainda muita controvérsia sobre o tema. Objetivos Apresentar uma revisão sistemática da literatura sobre a dinâmica dos mecanismos de depressão (DF) e de aumento (AF) da força isométrica após encurtamento e alongamento ativos, respectivamente, identificando as principais variáveis intervenientes nos fenômenos, e as principais teorias e hipóteses elaboradas para explicá-los até a presente data. Métodos O procedimento de busca da literatura foi composto por uma pesquisa nas principais bases de dados, incluindo artigos que observaram diretamente os fenômenos DF e AF, ou possíveis mecanismos e causas associadas a suas respectivas manifestações, desde os primeiros estudos sobre o tema até o ano de 2010. Resultados Foram encontradas 97 referências que atenderam aos critérios adotados. Conclusão Com base na revisão produzida, sugere-se a teoria da inibição por estresse induzido das pontes cruzadas de actina-miosina para explicar o fenômeno DF. Quanto ao fenômeno AF uma teoria tem sido bem aceita, a do aumento do número de pontes cruzadas de actina-miosina em estado forte de ligação influenciado pelo recrutamento dos componentes elásticos passivos, atribuindo-se aos filamentos de titina este papel.

Introduction The isometric force history dependence of skeletal muscle has been studied along the last one hundred years. Several theories have been formulated to explain and establish the causes of the phenomenon, but not successfully, as they have not been fully accepted and demonstrated, and much controversy on such a subject still remains. Objective To present a systematic literature review on the dynamics of the mechanisms of force depression and force enhancement after active shortening and lengthening, respectively, identifying the key variables involved in the phenomenon, and to date to present the main theories and hypothesis developed trying to explaining it. Method The procedure of literature searching complied the major databases, including articles either, those which directly investigated the phenomena of force depression and force enhancement or those which presented possible causes and mechanisms associated with their respective events, from the earliest studies published until the year of 2010. Results 97 references were found according to the criteria used. Conclusion Based on this review, it is suggested that the theory of stress inhibition of actin-myosin cross-bridges is that better explain the phenomenon of force depression. Whereas regarding the force enhancement phenomenon, one theory have been well accepted, the increased number of actin-myosin cross-bridges in strong binding state influenced by the recruitment of passive elastic components, which hole is attributed to the titin filament.

O avanço tecnológico das últimas décadas tem proporcionado o uso eficaz de técnicas não-invasivas na neuromodulação cerebral. Atualmente, as principais técnicas de neuromodulação são a estimulação magnética transcraniana (EMT) e a estimulação transcraniana por corrente contínua (ETCC). Por meio de revisão da literatura, o presente estudo aborda: a) história da estimulação cerebral; b) mecanismos de ação estudados através da neurofisiologia motora, farmacologia, neuroimagem e animais experimentais; c) perspectivas de aplicações da estimulação cerebral para promoção da saúde e melhoria do desempenho físico, incluindo o controle autonômico cardíaco e hipotensão pós-exercício, o controle de apetite e a modulação da fadiga e desempenho físico; e d) aspectos de segurança referentes ao uso da ETCC. Dessa forma, a ETCC parece ser uma técnica efetiva e segura para modular a função cerebral e podemos vislumbrar algumas perspectivas de aplicação no âmbito da ingestão alimentar, saúde cardiovascular e desempenho físico.

The technological advances of the last decades have provided the effective use of noninvasive techniques in neuromodulation with concomitant health benefits. Currently, the main neuromodulation techniques are transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). Through literature review, this study addresses the a) history of brain stimulation and the b) mechanisms of action studied by motor neurophysiology, pharmacology, neuroimaging, and experimental animals. Moreover, it is presented the c) perspectives for applications of brain stimulation for promoting health and improving physical performance, including cardiac autonomic control and post-exercise hypotension, control and modulation of appetite, fatigue and physical performance. Finally, we describe d) the security aspects related to the use of tDCS. Thus, tDCS seems to be an effective and safe technique to modulate brain function and suggests some application associated to food intake, cardiovascular health and physical performance.