Moving objects by imagination? Amount of finger movement and pendulum length determine success in the Chevreul pendulum illusion.

Hand-held pendulums can seemingly oscillate on their own, without perceived conscious control. This illusion, named after Chevreul, is likely a result of ideomotor movements. While this phenomenon was originally assumed to have a supernatural basis, it has been accepted for over 150 years that the movements are self-generated. However, until now, recordings of the small movements that create these oscillations have not been performed. In this study, we examined how participants produce these unconscious oscillations using a motion capture system. As expected, the Chevreul pendulum illusion was produced when the fingers holding the pendulum generated an oscillating frequency close to the resonant frequency of the pendulum, where very small driving movements of the arm are sufficient to produce relatively large pendulum motion. We found that pendulum length significantly affected the ability to produce the illusion - participants were much more successful with a 40 cm compared to an 80 cm pendulum. Further, we found that participants that tended to move their fingers more were more successful in producing the illusion but did not find a connection between inter-joint coordination and ability to generate the illusion.

Sauté External Rotation in Beginner and Advanced Ballet Dancers Trained in Different Backgrounds The Turnout Paradigm.

This study compared lower limb external rotation kinematic patterns during sautés in first position in beginners and experienced ballet dancers with various training backgrounds. The ability to attain a perfect turnout is traditionally thought to be a fundamental aspect of classical ballet, and turnout is identified in the literature as one of the leading causes of dance-related injuries and technical limitations among dancers. Twenty-eight ballet dancers of different technical levels and methods (three groups) were assessed. Coefficients of variation (CV), range of motion (ROM), and mean external rotation angles of hip, knee, and ankle in first position sauté were calculated. Differences among groups were tested with ANOVAs (Tukey's post hoc; p < 0.05). The hip mean external rotation values found during the jump were different between both experienced groups from different training backgrounds (p = 0.02). The inexperienced group presented a significantly greater hip external rotation CV compared to the experienced groups (p ≤ 0.001). There were no differences between groups for values of external rotation at the knee and ankle. It is concluded that higher technical level dancers produce lower variability of hip external rotation while performing sauté in first position. Ballet training background also seems to influence the hip external rotation pattern. Moreover, the knee contributes decisively to turnout composition, not only the hip, as expected.

Comparação da atividade eletromiográfica em músculos do powerhouse no roll up e roll back no solo e no Cadillac do método Pilates / Comparison of electromyographic activity of powerhouse muscles performing the roll up and roll back on the floor and on the Cadillac Pilates method

Introdução: A lombalgia é um problema de saúde pública que acomete grande parte da população em algum momento da vida. Exercícios físicos realizados pelo método Pilates são descritos na literatura como uma opção de tratamento. Entretanto, existem poucos estudos que elucidam movimentos adequados para este fim. Objetivo: Comparar a ativação elétrica dos músculos oblíquo externo, oblíquo interno e multífido durante exercícios abdominais no solo e no Cadillac, para identificar diferenças na atividade neuromuscular da musculatura flexora e extensora do tronco. Material e métodos: Onze mulheres realizaram oito repetições dos exercícios The Roll Up e Roll Back. Durante os movimentos, foi avaliada a extensão e flexão do quadril a partir da análise eletromiográfica de superfície. Resultados: A ativação eletromiográfica do músculo oblíquo externo foi estatisticamente significativo, nas duas fases do movimento, no exercício The Roll Up em comparação ao exercício Roll Back. Contudo, oblíquo interno e multífido não apresentaram diferenças quando comparados os exercícios. Conclusão: O exercício realizado no solo (The Roll Up) apresentou maior demanda da musculatura flexora e extensora. Esse achado representa um passo importante na compreensão de critérios objetivos para a elaboração de programas de reabilitação nas lombalgias e para o condicionamento físico utilizando o método Pilates.(AU)

Introduction: Low back pain is a public health problem and a large number of people suffer from it at some point in life. Physical exercises performed by the Pilates method are described in the literature as a treatment option. However, there are few studies that allow the development of appropriate actions for this purpose. Objective: Compare the electrical activation of external oblique, internal oblique and multifidus muscles during abdominal exercises on the floor and on the Cadillac, in order to identify the neuromuscular activity of the flexor and extensor musculature of the trunk. Methods: Eleven women performed eight repetitions of "The Roll Up" and "Roll Back" exercises. During the movements, the electromyographic surface analysis was used to measure the hip extension and flexion. Results: The electromyographic activation of the external oblique muscle was statistically significant, in the two stages of movement, The Roll Up exercise in comparison with the Roll Back exercise. However, internal oblique and multifidus did not show significant differences when exercises were compared. Conclusion: The exercise performed on the floor (The Roll Up) showed greater demand of the flexor and extensor muscles. This finding represents an important step in the understanding of objective criteria for the elaboration of rehabilitation programs in low back pain and for physical conditioning using the Pilates method. (AU)

Electrical Activity of Powerhouse Muscles During the Teaser Exercise of Pilates Using Different Types of Apparatus.

We compared the electrical activity of certain powerhouse muscles-External Oblique, Multifidus, Adductor Longus, and Gluteus Medius-during the teaser exercise of the Pilates Method, performed on various types of apparatus-the Mat, Reformer, and Wall Unit. Fifteen female practitioners of the Classic Pilates Method (32.6 ± 7.7 years old; 21.9 ± 1.9 body mass index) performed the teaser in each situation while electromyographic (EMG) and kinematic data were collected. Root mean square values of the flexion phase were compared. All muscles showed higher EMG activity in Reformer compared with Wall Unit, and Multifidus, Adductor Longus, and Gluteus Medius showed higher EMG activity in Mat compared with Wall Unit. No difference was found between Reformer and Mat.

Muscle strategies for leg extensions on a "Reformer" apparatus.

Considering the kinematics of leg extensions performed on a Reformer apparatus, one would expect high activation of hip and knee extensor muscle groups. However, because of the bi-articular nature of some lower limb muscles, and the possibility to vary the direction of force application on the Reformer bar, muscles can be coordinated theoretically in a variety of ways and still achieve the desired outcome. Hence, the aim of this study was to determine the knee and hip moments during leg extensions performed on the Reformer apparatus and to estimate the forces in individual muscles crossing these joints using static optimization. Fifteen subjects performed leg extensions exercises on the Reformer apparatus using an individually chosen resistance. To our big surprise, we found that subjects performed the exercise using two conceptually different strategies (i) the first group used simultaneous hip and knee extension moments, (ii) while the second group used simultaneous hip flexion and knee extension moments to perform the exercise. These different strategies were achieved by changing the direction of the resultant force applied by the subject's feet on the Reformer bar. While leg extensions on the Reformer apparatus have been thought to strengthen the hip and knee extensors muscles, our results demonstrate that patients can perform the exercise in a different and unexpected way. In order to control the hip and knee moments and achieve the desired outcome of the exercise, the direction of force application on the Reformer bar must be controlled carefully.

An instrumented footbar for evaluating external forces in Pilates.

The intensity of Pilates exercises is almost exclusively based on experience. Therefore, knowing the precise amount of effort that is exerted during exercises could be useful for professionals conducting exercise assessments and for future research using inverse dynamics (ID) analyses. The reformer is an apparatus that contains a carriage on rails to which resistance is applied via springs attached to the carriage. Subjects apply force to a footbar to displace the carriage, but the magnitude and direction of this force are unknown and need to be quantified if the ID approach is to be used. This study aimed to develop and describe a device built with commercial load cells attached to the reformer's footbar, with the device capable of measuring the direction and magnitude of the force exerted on the reformer's footbar, and to compare the force found using the device with the force estimated using the springs' parameters. To illustrate the device's use, one volunteer performed footwork exercises at different speeds and with different foot support positions and loads. External force estimated by the springs' level of deformation was significantly different (P < .001) from the magnitude of force acquired using the device, showing that the estimation is imprecise.

The influence of kihap on the impact of Dolio-chagui kicks in taekwondo / A influência do kihap sobre o impacto de chutes Dolio-Chagui no taekwondo / La influencia de kihap sobre el impacto de las patadas Dolio-Chagui en taekwondo

The kihap is a technique used in several oriental martial arts. It is a yell used by practitioners with the ex pectation of enhancing the force of a hit. However, the real effect of using the kihap is unknown. Therefore, this study aims to compare the peak of acceleration of the Dolio-chagui kick in taekwondo performed with and without the use of kihap. Twenty two experienced taekwondo practitioners performed 30 kicks each against a punching bag, alternating in random order with and without kihap, while the acceleration of the punching bag was measured. A t-test was used to compare the difference between the mean acceleration in both conditions. Higher values were found with the use of kihap (7.8 ± 2.8 g) than without the use of kihap (7.1 ± 2.4 g), p < 0.01, r = 0.57. The results indicate that kihap enhances the impact of the kick.

O kihap é uma técnica utilizada em diversas artes marciais orientais. Ele é um grito utilizado pelo praticante com a expectativa de aumentar a força do golpe. Entretanto, o real efeito do uso do kihap é desconhecido. Assim, esse estudo tem por objetivo comparar o pico de aceleração do chute Dolio-chagui do taekwondo realizado com e sem o uso de kihap. Vinte e dois praticantes experientes de taekwondo realizaram 30 chutes contra um saco de pancadas, alternando em ordem randomizada com e sem o uso do kihap, enquanto a aceleração do saco de pancadas foi mensurada. Um teste-t foi utilizado para comparar a diferença entre a aceleração média em ambas as condições. Valores mais altos foram encontrados com o uso do kihap (7,8 ± 2,8 g) do que sem o uso do kihap (7,1 ± 2,4 g), p < 0,01, r = 0,57. Os resultados indicam que o kihap aumenta o impacto do chute.

El kihap es una técnica utilizada en varias artes marciales orientales. Es un grito utilizado por los practicantes con la expectativa de mejorar la fuerza de un golpe. Sin embargo, se desconoce el efecto real de la utilización del kihap. Por lo tanto, este estudio tiene como objetivo comparar el pico de la aceleración de la patada Dolio-chagui en taekwondo realizado con y sin el uso del kihap. Veintidós practicantes de taekwondo experimentados realizaron 30 patadas cada uno contra un saco de boxeo, alternando en orden aleatorio con y sin kihap, mientras la aceleración del saco de boxeo fue medida. Se utilizó una prueba t para comparar la diferencia entre la aceleración media en ambas condiciones. Los valores más altos fueron encontrados con el uso de kihap (7,8 ± 2,8 g) que sin el uso de kihap (7,1 ± 2,4 g), p <0,01, r = 0,57. Los resultados indican que el kihap mejora el impacto de la patada.

Análise eletromiográfica dos músculos reto femoral e reto abdominal durante a execução dos exercícios hundred e teaser do método pilates / Electromyographic analysis of the rectus femoris and rectus abdominis muscles during performance of the hundred and teaser pilates exercises

A literatura tem mostrado que pequenas modificações em um exercício do método Pilates podem alterar o padrão de ativação muscular. Além disto, são poucos os estudos que avaliaram exercícios desse método do ponto de vista cinesiológico. Nesta perspectiva, o objetivo deste trabalho foi comparar dois exercícios realizados no solo e em aparelho no que diz respeito à ativação elétrica de grupos musculares atuantes. Participaram do estudo 11 mulheres saudáveis praticantes do método Pilates. Foram coletados dados eletromiográficos dos músculos reto femoral e reto abdominal, porções direita e esquerda, enquanto os exercícios hundred no solo, hundred no Reformer, teaser no solo e teaser no Cadillac eram mantidos na postura isométrica. Foram analisados os cinco segundos centrais de cada execução, normalizados por contração voluntária máxima. A análise estatística apresentou diferença entre a ativação dos grupos musculares, sendo maior no reto femoral, e interação entre músculos e exercício, onde no exercício hundred no solo e no Reformer o reto femoral teve maior ativação, enquanto no exercício teaser o reto abdominal foi mais ativo quando executado no Cadillac. Com base nos resultados do estudo pode-se afirmar que: i) quando comparados os exercícios hundred (no solo e no Reformer) e teaser (no solo e no Cadillac), não houve diferença entre os exercícios no que se refere à ativação dos músculos reto abdominal e reto femoral; ii) quando comparados os grupamentos musculares, o reto femoral apresentou maiores níveis de ativação nos exercícios hundred executado no solo e no Reformer, enquanto o reto abdominal apresentou maior ativação durante o exercício teaser executado no Cadillac.

The literature has shown that small modifications in a Pilates method exercise may change the muscles activation pattern. Moreover, few studies have evaluated Pilates' exercises from the kinesiology point of view. Therefore, this study aimed to compare a couple of exercises performed on the mat and in apparatus regarding electric activation of acting muscle groups. Eleven healthy Pilates trained women took part in the study. Electromyographic data were collected from the rectus femoris and rectus abdominis muscles, right and left portions, while keeping the isometric posture of the hundred on mat, hundred on the Reformer machine, teaser on mat and teaser on the Cadillac machine exercises. The five central seconds of each execution normalized by maximum voluntary contraction were analyzed. Statistical analysis showed difference between the muscle group's activation that was higher for the rectus femoris, and interaction between muscle and exercise, where rectus femoris muscle's electric activation was higher on the hundred exercise performed on mat and Reformer and rectus abdominis muscle's electric activation was higher on teaser performed in the Cadillac machine. Based on the study results, it may be stated that: (i) when compared the hundred (on mat and Reformer) and teaser (on mat and Cadillac) exercises were compared, no difference was found between them regarding rectus abdominis and rectus femoris muscles' activation; (ii) when muscle groups were compared, the rectus femoris presented higher activation levels on the hundred exercise performed on mat and Reformer, while rectus abdominis presented higher activation during the teaser exercise performed on Cadillac.

Análise mecânica e estimativa da força muscular resultante no aparelho flexor dorsal do pé / Mechanical analysis and estimation of muscle strength resulting in apparatus flexor dorsal foot

Embora a importância do reforço dos dorsiflexores seja conhecida, muitas vezes esses músculos são negligenciados em um programa de treinamento. O objetivo desse estudo é analisar o comportamento do torque resistente do “aparelho flexor dorsal do pé” e analisar o comportamento da força muscular resultante durante o exercício. Para tanto, foram elaborados diagramas de corpo livre da parte móvel do aparelho e do segmento humano e, também, foram determinadas equações de equilíbrio de torque, em que a velocidade foi considerada constante. Os resultados indicam que o torque de resistência do aparelho é crescente até chegar à horizontal e decrescente a partir desse ponto. A força muscular resultante é crescente durante todo o movimento e mais notadamente após a horizontal.

Although the importance of the dorsiflexors muscle work is well known, very often these muscles are neglected in a workout-training program. The aim of this study is to analyze the behavior of the resistant torque on the “dorsiflexors machine” and, also, analyze how the muscle force output during the exercise is. For that, there were designed free body diagrams of the movable part of the machine and human segment. There were made torque equilibrium equations where the velocity was considered to be steady. Our results suggest the resistant torque increases till it gets at the horizontal line and it decreases from this spot on. As for the muscle force output it increases for all over the range of movement and it is more evident after the horizontal line.