Evaluating the Effect of the Combat Style Congruency on Performance and Fatigability in Brazilian Jiu-Jitsu: A Pilot Study.

PURPOSE: Brazilian jiu-jitsu is a martial art emphasizing ground combat with multiple ramifications to self-defense and military training. Some Brazilian jiu-jitsu athletes prefer fighting on their back (Guardadors), while others preferentially adopt a standing or kneeling position (Passadors). Whether the combat scenario leading to adopt a preferential or nonpreferential combat style influences the combat outcomes remains unexplored. METHODS: In a counterbalanced design, 13 athletes performed simulated combats from either a congruent or incongruent scenario with regard to their preferred combat style. We collected combat scores from the official ranking system and measured upper- and lower-limb explosive performance before and after the combats, as well as the rating of perceived exertion and blood lactate concentrations to index fatigability. RESULTS: Passadors had greater grip strength than Guardadors (Rp2 = .23, P = .03), whereas Guardadors showed higher lower-limb performance (Rp2 = .16, P = .05). When forced to combat as Passadors, Guardadors exhibited greater grip-strength impairment and a greater increase in perceived exertion (Rp2 = .12, P = .04; Rp2 = .15, P = .05, respectively). They also had higher blood lactate concentrations (Rp2 = .19, P = .02). CONCLUSION: Guardadors exhibited greater fatigability after fighting from an incongruent combat situation compared to Passadors, presumably due to greater difficulties to adjust to the loss of initiative when restricted to a primarily defensive role. Future studies should examine how combat style congruency might affect performance and influence recovery strategies during high-level competitive events.

Revisiting the acute effects of resistance exercise on motor imagery ability.

Motor imagery (MI) shares psychological and physiological similarities with the physical practice of the same action. Yet, it remains unclear whether fatigue elicited by exercise impairs MI ability. Fourteen participants performed MI of a self-paced walking sequence of 22 m before and after a resistance exercise eliciting muscle fatigue from upper and lower limbs, selectively. We indexed MI ability using psychometric and behavioral methods. Electromyography of the quadriceps was also recorded during physical practice trials of the walking sequence. For both experimental conditions, we recorded improved temporal congruence between MI and physical practice of the walking sequence (9.89 %, 95 % CI [7.03, 12.75], p < 0.01). Vividness decreased immediately after the fatiguing exercise (6.35 %, 95 % CI [5.18, 7.51], p < 0.05), before rapidly returning to pre-fatigue values during recovery trials. The results challenge the hypothesis of an effect of acute fatigue elicited by a resistance exercise on MI ability, i.e. restricted to MI tasks focusing fatigued effectors. The beneficial effects of fatigue conditions on the psychometric and behavioral indexes of MI ability are discussed in the broader context of psychobiological fatigue models linking perceived exertion with the reallocation of attentional resources. The general perception of fatigue, rather than local muscle fatigue, appeared linked to the acute effects of resistance exercise on MI ability.

Stabilometric Correlates of Motor and Motor Imagery Expertise.

Motor Imagery (MI) reproduces cognitive operations associated with the actual motor preparation and execution. Postural recordings during MI reflect somatic motor commands targeting peripheral effectors involved in balance control. However, how these relate to the actual motor expertise and may vary along with the MI modality remains debated. In the present experiment, two groups of expert and non-expert gymnasts underwent stabilometric assessments while performing physically and mentally a balance skill. We implemented psychometric measures of MI ability, while stabilometric variables were calculated from the center of pressure (COP) oscillations. Psychometric evaluations revealed greater MI ability in experts, specifically for the visual modality. Experts exhibited reduced surface COP oscillations in the antero-posterior axis compared to non-experts during the balance skill (14.90%, 95% CI 34.48-4.68, p < 0.05). Experts further exhibited reduced length of COP displacement in the antero-posterior axis and as a function of the displacement area during visual and kinesthetic MI compared to the control condition (20.51%, 95% CI 0.99-40.03 and 21.85%, 95% CI 2.33-41.37, respectively, both p < 0.05). Predictive relationships were found between the stabilometric correlates of visual MI and physical practice of the balance skill, as well as between the stabilometric correlates of kinesthetic MI and the training experience in experts. Present results provide original stabilometric insights into the relationships between MI and expertise level. While data support the incomplete inhibition of postural commands during MI, whether postural responses during MI of various modalities mirror the level of motor expertise remains unclear.

Effect of Physical Fatigue Elicited by Continuous and Intermittent Exercise on Motor Imagery Ability.

Purpose: The ability to perform motor imagery (MI) might be impaired by the physical fatigue elicited during training. Interestingly, there is also theoretical support for a more limited influence of fatigue in the existing literature. Method: We evaluated MI ability before and after two exercise protocols: (i) a continuous exercise of 20 min performed on a cycle ergometer at 80% of the secondary ventilatory threshold (Continuous exercise), and (ii) an intermittent exercise of 20 min involving sprints at maximal intensity performed with regular intervals (Intermittent exercise). MI ability evaluations were performed using validated behavioral (mental chronometry) and psychometric (subjective reports) methods. MI ability evaluations included mental rehearsal of a motor sequence which involved the main effectors of the exercise protocols (walking), and mental rehearsal of a motor task which did not involve the main somatic effectors of the exercise protocols (pointing movements with the upper limbs). Results: Mental chronometry showed that MI ability was degraded only after Intermittent exercise, while self-report measures of MI vividness revealed that MI ability was primarily impaired during MI of the walking task. Conclusions: Present results suggest that Intermittent exercise engaging anaerobic processes of energy expenditure, but not Continuous exercise engaging aerobic processes of energy expenditure, impaired MI ability. Findings are discussed in relation to the internal models theory of motor simulation, specifically changes in current state of the motor system under the fatigued state-affecting motor predictions. Present findings may contribute to successful applications of MI training in sports and rehabilitation.

Effects of Action Observation and Action Observation Combined with Motor Imagery on Maximal Isometric Strength.

Action observation (AO) alone or combined with motor imagery (AO + MI) has been shown to engage the motor system. While recent findings support the potential relevance of both techniques to enhance muscle function, this issue has received limited scientific scrutiny. In the present study, we implemented a counterbalanced conditions design where 21 participants performed 10 maximal isometric contractions (12-s duration) of elbow flexor muscles against a force platform. During the inter-trial rest periods, participants completed i) AO of the same task performed by an expert athlete, ii) AO + MI, i.e. observation of an expert athlete while concurrently imagining oneself performing the same task, and iii) watching passively a video documentary about basketball shooting (Control). During force trials, we recorded the total force and integrated electromyograms from the biceps brachii and anterior deltoideus. We also measured skin conductance from two finger electrodes as an index of sympathetic nervous system activity. Both AO and AO + MI outperformed the Control condition in terms of total force (2.79-3.68%, p < 0.001). For all conditions, we recorded a positive relationship between the biceps brachii activation and the total force developed during the task. However, only during AO was a positive relationship observed between the activation of the anterior deltoideus and the total force. We interpreted the results with reference to the statements of the psycho-neuromuscular theory of mental practice. Present findings extend current knowledge regarding the priming effects of AO and AO + MI on muscle function, and may contribute to the optimization of training programs in sports and rehabilitation.

Neurophysiological insights on flexibility improvements through motor imagery.

The efficacy of motor imagery (MI) practice to facilitate muscle stretching remains controversial and the underlying neurophysiological mechanisms unexplored. We evaluated the effects of MI practice during a sit-and-reach task. Healthy participants were randomly assigned to a MI practice (n=15) or Control (n=15) group and completed 2 blocks of 5 sit-and-reach trials. During the first block (B1), participants performed 5 maximal stretching trials of 10s. During the second block (B2), trials were divided into two consecutive parts: i) reproducing the maximum performance of B1 (10s, B2 part 1), and ii) attempting to outperform the maximum performance of B1 (10s, B2 part 2). Participants performed kinesthetic MI of hamstring stretching during B2 trials in the MI practice group. We recorded electromyography from the hamstring and rectus femoris of the dominant leg. We also processed skin conductance as an index of sympathetic activity. We measured greater performance improvements from B1 to B2 part 2 in the MI practice group compared to Control (p<0.05). Participants in the MI practice group exhibited reduced hamstring activation during both B2 part 1 (p<0.001) and B2 part 2 (p<0.001) compared to Control. Skin conductance revealed higher sympathetic activation during B2 part 2 compared to both B1 and B2 part 1 in the two groups. Thus, performing MI during actual movement is likely to improve stretching performance through reduced muscle activation. Such improvement may be grounded in a cortical gain over spinal reflexes.

Selective Efficacy of Static and Dynamic Imagery in Different States of Physical Fatigue.

There is compelling evidence that motor imagery contributes to improved motor performance, and recent work showed that dynamic motor imagery (dMI) might provide additional benefits by comparison with traditional MI practice. However, the efficacy of motor imagery in different states of physical fatigue remains largely unknown, especially as imagery accuracy may be hampered by the physical fatigue states elicited by training. We investigated the effect of static motor imagery (sMI) and dMI on free-throw accuracy in 10 high-level basketball athletes, both in a non-fatigued state (Experiment 1) and immediately after an incremental running test completed until exhaustion (20 m shuttle run-test-Experiment 2). We collected perceived exhaustion and heart rate to quantify the subjective experience of fatigue and energy expenditure. We found that dMI brought better shooting performance than sMI, except when athletes were physically exhausted. These findings shed light on the conditions eliciting optimal use of sMI and dMI. In particular, considering that the current physical state affects body representation, performing dMI under fatigue may result in mismatches between actual and predicted body states.

Acute effect of motor imagery on basketball players' free throw performance and self-efficacy / Efeito agudo da imagetica no desempenho de lances livres e percepcao de autoeficacia em atletas

It is becoming ever more common for the difference between winning and losing in sport to be decided by the smallest details. In basketball, free throws can be a differentiating factor between teams and motor imagery (IMA) has been studied as a potential ergogenic agent to improve free throw performance, but little attention as been given to its acute effects, particularly among athletes. The objective of this study was to investigate the effect of a single mental training session on the free throw performance and self-efficacy of young athletes. Eleven young basketball players from the Federação Paulista de Basquete junior league were enrolled on the study. Players were either allocated to an IMA group and watched a 1 minute video before a 3-minute motor imagery session, or to a control group and were rested for 4 minutes, before taking 10 free throw shots in both cases. All participants completed a self-efficacy questionnaire before and after the intervention. Statistical analysis was conducted using the Mann-Whitney U test and the Wilcoxon test, plus measures of Smallest Worthwhile Change (SWC). There were no significant difference between median results for the two groups, but the SWC statistic indicated an 84% likelihood that mental training had a beneficial effect on performance in the first two free throws. It is concluded that motor imagery used in advance has an 84% chance of having a beneficial effect on performance in up to two free throws.

O esporte cada vez mais diferencia vencedores e perdedores por mínimos detalhes. No basquetebol um fator diferenciador é o lance livre. Sessões de imagética motora (IMA) vêm sendo estudada como um ergogênico sobre o desempenho de lance livre, porém, pouco se estuda o seu efeito agudo, principalmente, em atletas. O objetivo desse estudo foi verificar o efeito de uma sessão prévia de treinamento mental sobre o desempenho no lance livre e na percepção de autoeficácia de jovens atletas. Participaram do estudo 11 atletas juvenis da Federação Paulista de Basquete. Na condição IMA, foram submetidos a 1 minuto de vídeo + 3 minutos de imagética, seguidos de 10 lances livres, e no controle, 4 minutos de repouso seguidos de 10 lances livres. O questionário de autoeficácia foi preenchido antes e após a intervenção. Para análise estatística, foram utilizados os testes U de Mann-Withney, Wilcoxon e o Smallest Wothwhille Change (SWC). Não foi encontrada diferença entre a mediana dos grupos, porém, o SWC apontou uma possibilidade de 84% de efeito benéfico do treinamento mental sobre o desempenho para até 2 lances livres. Concluiu-se que a imagética motora prévia tem 84% de chance de causar um efeito benéfico sobre o desempenho de lance livre em até 2 arremessos.

Música: un recurso psicofisiológico para el ejercicio físico y deporte / Music: a psychophysiological aid to physical exercise and sport

El uso de la música se ha identificado como un auxiliar ergogénico potencial que ayuda a mejorar el rendimiento en el ejercicio. La música ha sido clasificada como una ayuda ergogénica psicológica y ha despertado el interés principalmente por sus efectos encontrados en estudios con un enfoque en el rendimiento durante, antes y después del ejercicio, En este contexto, el objetivo de este estudio fue revisar la literatura sobre los principales efectos de la música sobre el rendimiento y sus posibles mecanismos, cubriendo nuevas perspectivas sobre el tema. El método consistió en la búsqueda, selección y estratificación de los artículos originales de grandes bases de datos (Medline, Sport Discuss, Scopus, Web of Science and Scielo) que utilizan los descriptores: música, ejercicio, rendimiento y fatiga. Se consideraron todos los modelos y tipos de ejercicio y música. Estos artículos indican que el uso de la música como un auxiliar ergogénico podría ser eficaz para mejorar el rendimiento; disminuir la tasa de percepción de esfuerzo y es capaz de ofrecer mejores sensaciones con el ejercicio, de acuerdo con el tiempo de aplicación, la condición física de los sujetos, el tipo de ejercicio y componentes musicales, respetando algunas recomendaciones y orientaciones para la inserción. Los principales mecanismos de acción propuestos por los efectos ergogénicos de la música se basan en la hipótesis de comportamiento y se siguen discutiendo; tampoco hay evidencias suficientes para descartar cualquiera de ellos, lo que demuestra la necesidad de estudios futuros en un intento por aclarar tales efectos en el sistema nervioso central. Para resumir todo esto, proponemos algunas orientaciones de uso en el ejercicio submáximo y máximo, permitiendo que los entrenadores y atletas aplicar esta técnica en sus métodos de entrenamiento (AU)

The use of music has been identified as a potential ergogenic aid that helps to improve performance in exercise. Music has been classified as a psychological ergogenic aid and has attracted interest mainly for its effects found in studies with a focus on performance during exercise, pre-task and post-task. In this context, the objective of this study was to review the literature about the main effects of music on performance and their possible mechanisms, covering new perspectives about the theme. The method consisted of search, selection and stratification of the original articles of major databases (Medline, Sport Discuss, Scopus, Web of Science and Scielo) using the descriptors music, exercise, performance and fatigue. We considered all models and types of exercise and music. These articles suggest that the use of music as an ergogenic aid could be efficient to improve performance; decrease rate perceived of exertion and is capable to bring better feelings to exercise, according to time of application, physical fitness of subjects, type of exercise and musical components, respecting some recommendations and orientations to insertion. The main proposed mechanisms of action for the music ergogenic effects are based on behavioral hypothesis and are still being discussed; also there are not enough evidences to discard any of them, demonstrating the need for future studies in attempt to clarify such effects in central nervous system. To sum it all up, we propose some orientations of use in submaximal and maximal exercise, allowing coaches and athletes apply this technique in their methods of training (AU)

La activación de la corteza prefrontal durante las tareas motrices y perspectivas de diferentes imágenes visuales en los hombres y las mujeres: un estudio de la espectroscopia de reflectancia en el infrarrojo funcional (fNIRS) / Ativação do córtex pré-frontal durante tarefas motoras e perspectivas de diferentes imagens visuais em homens e mulheres: um estudo com espectroscopia por reflectância infravermelho funcional (fNIRS) / Equal prefrontal cortex activation between males and females in a motor tasks and different visual imagery perspectives: a functional near-infrared spectroscopy (fNIRS) study

The purpose of this study was to compare the prefrontal cortex (PFC) blood flow variation and time on in males and females while performing a motor task and imagery perspectives. Eighteen right handed subjects (11 males and 7 females) were volunteers to this study. All subjects went through three randomly conditions, a motor task condition (MT) in which they had to do a simple finger tap. The other conditions included practicing imagery in first and third views. During all the conditions, the fNIRS device was attached to the subject forehead to obtain the blood flow; the total time in each task which was measured with a chronometer. No difference had been found in any condition for both sexes in the PFC and time, nor for all subjects integrated in the PFC. Therefore, we conclu-de that both imageries can be used to mentally train a motor task, and probably both sexes can be benefited.

O objetivo do estudo foi comparar a variação sanguínea do córtex prefrontal (CPF) e o tempo de realização, durante uma tarefa motora e diferentes perspectivas de imagética motora em homens e mulheres. Dezoito sujeitos destros (11 homens e 7 mulheres) foram voluntários. Todos os sujeitos passaram por 3 condições randomicamente, uma tarefa motora que consistia em uma simples batida de dedos. As outras condições fora a prática de imagética motora em primeira e terceira pessoa. Durante todas as condições, um aparelho fNIRS foi acoplado a testa para obtenção do fluxo sanguíneo; e o tempo total de cada tarefa foi obtido com um cronômetro. Nenhuma diferença foi encontrada em nenhuma condição para ambos os gêneros no CPF e no tempo, bem como quanto considerados todos os sujeitos. Concluímos que ambas imagéticas podem ser usadas para treinar mentalmente uma tarefa motora e que, provavelmente, ambos os gêneros podem se beneficiar da técnica.

El propósito de este estudio fue comparar la actividad de la corteza frontal (CF) y el tiempo del realización de una tarea motora en diferentes perspectivas del entrenamiento mental. Dieciocho participantes diestros (11 hombres y 7 mujeres) fueron voluntarios en este estudio. Todos los participantes realizaram tres condiciones aleatorias: tarea motora (TM), dónde hicieron golpes con los dedos en una secuencia determinada. Las otras condiciones estaban practicando el entrenamiento mental vistas en primera y tercera persona. Durante todas las condiciones, el dispositivo fNIRS estaba unido a la frente del sujeto para obtener el flujo de sangre; el tiempo total de cada tarea se midió con un cronómetro. Ninguna diferencia se había encontrado en ninguna condición para ambos sexos y el tiempo. Por lo tanto, llegamos a la conclusión de que ambas las formas de imaginación pueden utilizar para entrenar mentalmente una tarea motora, y probablemente ambos géneros pueden ser beneficiados.