Running economy (RE), defined as the energy demand for a given velocity of submaximal running, has been identified as a critical factor of overall distance running performance. Plyometric and resistance trainings, performed during a relatively short period of time (~15–30 days), have been successfully used to improve RE in trained athletes. However, these exercise types, particularly when they are unaccustomed activities for the individuals, may cause delayed onset muscle soreness, swelling, and reduced muscle strength. Some studies have demonstrated that exercise-induced muscle damage has a negative impact on endurance running performance. Specifically, the muscular damage induced by an acute bout of downhill running has been shown to reduce RE during subsequent moderate and high-intensity exercise (>65% VO2max). However, strength exercise (i.e., jumps, isoinertial and isokinetic eccentric exercises) seems to impair RE only for subsequent high-intensity exercise (~90% VO2max). Finally, a single session of resistance exercise or downhill running (i.e., repeated bout effect) attenuates changes in indirect markers of muscle damage and blunts changes in RE.

This study examined the effect of fast-velocity concentric isokinetic resistance training (FV) on the rate of force development (RFD) at early (<100 ms) and late phases (>100 ms) of rising muscle force. Nine men participated in a 6-week resistance training intervention for the lower body, and nine matched subjects participated as controls (CON). During concentric isokinetic (180°s(-1)) knee extension training, subjects were instructed to do each contraction 'as fast and forcefully as possible'. Maximal muscle strength (MVC) and RFD (0-10, 0-20, …, 0-250 ms from the onset of contraction) were measured during maximal voluntary isometric contraction of the knee extensors (KE). There were no significant changes in MVC of KE in both groups after intervention (FV = 314·2 ± 101·1 versus 338·7 ± 88·0 N∙m, P>0·05; CON = 293·3 ± 94·8 versus 280·0 ± 72·2 N∙m, P>0·05). The RFD increased 39-71% at time intervals up to 90 ms from the onset of the contraction (P<0·05), whereas no change occurred at later time intervals. Similarly, relative RFD (i.e.%MVC∙s(-1)) (RFDr) increased 33-56% at time intervals up to 70 ms from the onset of the contraction (P<0·05). It can be concluded that a short period of resistance training performed with concentric fast-velocity isokinetic muscle contractions is able to enhance RFD and RFDr obtained at the early phase of rising muscle force.

The aim of this study was to determine the correlation between the concentric hamstrings/quadriceps muscle strength (Hcon :Qcon ) and cross-sectional area ratios (Hcsa :Qcsa ) in professional soccer players with Hcon :Qcon imbalance. Nine male professional soccer players (25·3 ± 4·1 years) performed five maximal concentric contractions of the knee extensors (KE) and flexors (KF) at 60 s(-1) to assess Hcon :Qcon . The test was performed using the dominant (preferred kicking), and non-dominant limb with a 5-min recovery period was allowed between them. Only players with Hcon :Qcon < 0·60 (range: 0·45-0·59) in both limbs were included in this study. The muscle cross-sectional area (CSA) of KE and KF was determined by magnetic resonance imaging. The correlations between Hcon :Qcon and Hcsa :Qcsa in the dominant leg (r = -0·33), non-dominant leg (r = 0·19) and in the both legs combined (r = 0·28) were not statistically significant (P>0·05). Thus, the Hcon :Qcon seems not to be determined by Hcsa :Qcsa in professional soccer players with Hcon :Qcon imbalance.

RESUMO:Bemisia tabaci biótipo B é um dos principais insetos-praga na cultura da abobrinha (Cucurbita pepo L.). O manejo dessa mosca-branca tornou-se grande desafio aos agricultores, uma vez que esta apresenta rápida capacidade de desenvolver resistência a diferentes classes de inseticidas. Como alternativa vem sendo investigado o uso de extratos vegetais com atividades inseticida e/ou insetistática, os quais têm revelado resultados promissores no combate a inseto. O presente trabalho teve por objetivo avaliar os possíveis efeitos de sete extratos provenientes de cinco espécies vegetais, Ruta graveolens L. (folhas), Azadirachta indica A. Juss. (folhas + ramos), Trichilia pallida Swartz (ramos), T. pallida (folhas), A. indica (amêndoas), Chenopodium ambrosioides L. (inflorescências + ramos+ folhas) e Mentha pulegium L. (folhas), sobre Bemisia tabaci biótipo B em abobrinha, por meio de testes de repelência e deterrência para oviposição. Em teste com chance de escolha, avaliou-se a atratividade e determinou-se o índice de repelência após 6, 24 e 48 horas da aplicação dos extratos. A oviposição foi verificada após a terceira contagem do número de adultos. O extrato à base de folhas de M. pulegium mostrou repelência e deterrência à oviposição de B. tabaci biótipo B, podendo ser recomendado como alternativa para o manejo do inseto. In free choice tests, the attractiveness and determination of the rate of repellence (with 6, 24 and 48 hours after application of the extracts) were evaluated. The oviposition was observed after the third counting of the number of adults. The extract of leaves of M. pulegium showed repellence and oviposition deterrence to B. tabaci biotype B and may be recommended as an alternative in the insect management.Key words: Curcubitaceae, whitefly, plant extracts, alternative management INTRODUÇÃOAs cucurbitáceas ocupam lugar de destaque dentre as hortaliças no Brasil, uma vez que seus frutos constituem-se como grandes fontes de vitaminas A e D. As sementes, muito ricas em proteínas, podem ser também utilizadas na extração de óleos comestíveis, além de serem consumidas diretamente (Blanco et al., 1997).A ocorrência de pragas, doenças e o prateamento das folhas da aboboreira limitam a produção, causando prejuízos aos agricultores. Dentre as pragas associadas à cultura, destaca-se a moscabranca Bemisia tabaci (Gennadius) biótipo B, também

Postactivation potentiation (PAP) is known to enhance force production. Maximal isometric strength assessment protocols usually consist of two or more maximal voluntary isometric contractions (MVCs). The objective of this study was to determine if PAP would influence isometric strength assessment. Healthy male volunteers (n = 23) performed two five-second MVCs separated by a 180-seconds interval. Changes in isometric peak torque (IPT), time to achieve it (tPTI), contractile impulse (CI), root mean square of the electromyographic signal during PTI (RMS), and rate of torque development (RTD), in different intervals, were measured. Significant increases in IPT (240.6 ± 55.7 N·m versus 248.9 ± 55.1 N·m), RTD (746 ± 152 N·m·s−1 versus 727 ± 158 N·m·s−1), and RMS (59.1 ± 12.2% RMSMAX   versus 54.8 ± 9.4% RMSMAX) were found on the second MVC. tPTI decreased significantly on the second MVC (2373 ± 1200 ms versus 2784 ± 1226 ms). We conclude that a first MVC leads to PAP that elicits significant enhancements in strength-related variables of a second MVC performed 180 seconds later. If disconsidered, this phenomenon might bias maximal isometric strength assessment, overestimating some of these variables.

Abstract-Eccentric-based exercise is known to induce muscle damage (MD). The purpose of this study was to investigate effect of downhill walking (DW) sessions on MD and aerobic markers in young adults. Eight male subjects were submitted to a 4-week DW periodized exercise program. Subjects' soreness (SOR) was assessed each training day. Serum creatine quinase activity (CK) was collected before the first training session, and at the end of each of the four weeks. Oxygen uptake (VO 2 ) and perceived exertion (PE) were assessed during the last training session every week. Increases in SOR were found only at the third and fourth training days. Increased CK concentration was found at the third training week. No significant increases in VO2 and PE were found throughout the program. We concluded that DW sessions elicit significant MD, but not enough to impair it in further sessions. Therefore, DW can be used as a training protocol following proper periodization. Keywords: downhill walking, muscle damage, trainingResumo-"Monitoramento de marcadores de dano muscular durante um programa de quatro semanas de treinamento de caminhada em declive." Exercícios excêntricos costumam induzir dano muscular (DM). O objetivo deste estudo foi investigar respostas aeróbias e de DM a sessões de caminhada em declive (CaED) em adultos. Oito voluntários realizaram um programa periodizado de treinamento de CaED. A dor muscular (DMIT) foi coletada durante todos os dias de treinamento. A atividade sérica de creatina quinase (CK) foi coletada antes da primeira sessão e ao final das semanas 1-4. O consumo de oxigênio (VO 2 ) e a percepção de esforço (PE) foram coletados durante a última sessão de treinamento de cada semana. Aumentos na DMIT foram identificados no terceiro e quarto dias de treinamento. Os valores de CK se apresentaram aumentados na terceira semana. Não foram identificadas diferenças nos valores obtidos de VO2 e PE. Concluímos que sessões de CaED induzem DM, porém este não afeta sessões posteriores. Portanto, a CaED pode ser utilizada como um método de treinamento, possibilitando sua periodização. Palavras-chaves: caminhada em declive, dano muscular, treinamentoResumen-"Marcadores de monitoreo de daño muscular durante un programa de cuatro semanas de entrenamiento a pie cuesta abajo." Ejercicio excéntrico desacostumbrado es conocido por inducir daño muscular (DM). El objetivo de este estudio fue investigar las respuestas a sesiones de caminar cuesta abajo (DW) en los adultos jóvenes, la evaluación de MD y los marcadores de aeróbicos. Ocho sujetos varones fueron sometidos a un programa de ejercicios de periodización de DW de 4 semanas. El dolor de los sujetos (SOR) se evaluó todos los días de entrenamiento. Actividad de la creatina quinasa sérica (CK) se recogió antes de la primera sesión de entrenamiento, y al final de las semanas 1-4. El consumo de oxígeno (VO 2 ) y la percepción subjetiva del esfuerzo (PE) se evaluaron durante la última sesión de entrenamiento cada semana. Los aumentos en SOR se encontraron sólo en los tercero ...

ABSTRACT:The purposes of this study were: 1) to determine whether low intensity resistance training combined with blood flow restriction (LI-BFR) could affect the concentric hamstrings/quadriceps muscle strength ratio (Hcon:Qcon) of professional soccer players with Hcon:Qcon imbalance (Study 1), and; 2) whether hamstrings strength response observed after LI-BFR is associated with muscle hypertrophy (Study 2). In the Study 1, athletes were randomly divided into a training group (n = 6) and a control group (n = 5). In the Study 2, all athletes (n = 11) performed a LI-BFR training program. The athletes participated of a 6-week (twice a week) supervised training program (unilateral knee flexion at 30% 1RM) totalizing 12 training sessions. The concentric peak torque of knee flexors (+8%; P < 0.001) and Hcon:Qcon (+9%; P < 0.01) were significantly increased after LI-BFR. Moreover, the cross-sectional area (CSA) of the hamstrings was significantly increased (+10%; P < 0.001) after LI-BFR. Thus, the addition of hamstrings strength training program using LI-BFR during preseason is able to enhance both Hcon:Qcon and hamstrings CSA of professional soccer players with Hcon:Qcon imbalance.

-Eccentric exercise training using low intensity-high volume approach has been performed to improve maximal muscle strength and power. The aim of this study was to compare the effects of short-term downhill walking and level walking training on lower limb strength and maximal oxygen uptake of active individuals. Eighteen young adults were divided into level walking group (n = 9) or downhill walking training group (n = 9). Both groups performed a four-week training program. The level walking group performed seven level walking sessions per week, while the downhill walking group walked downhill (-16%) in the same weekly frequency. One week before and one week after the training protocol, maximal oxygen uptake, muscle-bone cross-sectional area and isometric peak torque of knee extensors and plantar flexors were assessed for both groups. A significant group vs. time interaction was found only for cross sectional area of plantar flexors (PF), showing increases for the downhill walking group (112.6 ± 28.9 cm 2 vs. 115.9 ± 29 cm 2 ) but not for the level walking group (94.9 ± 23.3 cm 2 vs. 94.6 ± 228 cm 2 ). Maximal oxygen uptake remained unaltered after training for both groups and IPT was increased after training for both groups. It was concluded that short-term downhill walking training does not seem to be efficient in promoting improvements in cardiorrespiratory fitness of young adults. However, it seems to promote gains in some variables related to neuromuscular fitness. Key words: Muscle strength; Physical endurance; Physical fitness. Resumo -O treinamento excêntrico de baixa intensidade e alto volume vem sendo adotado para desenvolver a força e a potência muscular. O objetivo deste estudo foi comparar os efeitos do treinamento de caminhada em declive e em plano, em parâmetros de força de membros inferiores e consumo máximo de oxigênio de indivíduos ativos. Dezoito adultos foram separados em grupos de treinamento em plano (GTP -n = 9) em declive (GTD -n = 9). Ambos realizaram um programa de treinamento de 4 semanas. O GTP realizou sete sessões semanais de caminhada no plano, enquanto o GTD caminhou em declive (-16%