Background: Hippotherapy uses horseback riding movements for therapeutic purposes. In addition to the horse's movement, the choice of equipment and types of floor are also useful in the intervention. The quantification of dynamic parameters that define the interaction of the surface of contact between horse and rider provides insight into how the type of floor surface variations act upon the subject's postural control. Objective: To test whether different types of surfaces promote changes in the amplitude (ACOP) and velocity (VCOP) of the center of pressure (COP) displacement during the rider's contact with the saddle on the horse's back. Method: Twenty two healthy adult male subjects with experience in riding were evaluated. The penetration resistances of asphalt, sand and grass surfaces were measured. The COP data were collected on the three surfaces using a pressure measurement mat. Results: ACOP values were higher in sand, followed by grass and asphalt, with significant differences between sand and asphalt (anteroposterior, p=0.042; mediolateral, p=0.019). The ACOP and VCOP values were higher in the anteroposterior than in the mediolateral direction on all surfaces (ACOP, p=0.001; VCOP, p=0.006). The VCOP did not differ between the surfaces. Conclusion: Postural control, measured by the COP displacement, undergoes variations in its amplitude as a result of the type of floor surface. Therefore, these results reinforce the importance of the choice of floor surface when defining the strategy to be used during hippotherapy intervention.

Sistemas de coroas não circulares e novas interfaces entre o pedal e o pedivela vem sendo propostas com o objetivo de otimizar variaveis relacionadas com o desempenho no ciclismo (e.g. pico de torque e eficiência) com resultados conflitantes acerca do desempenho. Nesta perspectiva, o objetivo desta revisão foi abordar aspectos teóricos do uso de sistemas de pedivela não circulares e novas interfaces entre o pedal e o pedivela e seus efeitos em variáveis biomecânicas, fisiológicas e do desempenho. A redução do trabalho interno, pico de torque no pedivela e tempo decorrido nos pontos mortos (posições de 12 horas e 6 horas) estiveram entre as variáveis utilizadas para otimizar o desenho de sistemas de pedivela não circulares e novas interfaces entre o pedal e o pedivela. Alterações na cinemática foram observadas sem mudanças na ativação dos músculos dos membros inferiores de ciclistas utlizando sistemas de pesdivela não-circulares e novas interfaces entre o pedal e o pedivela. Resultados conflitantes foram observados na economia/eficiência indicando beneficios pouco claros do uso de sistemas de pedivela não circulares e resultados positivos do uso de novas interfaces entre o pedal e o pedivela na economia/eficiência.

Noncircular chainrings and novel pedal to crank interfaces have been designed to optimize variables related to cycling performance (e.g. peak crank torque and efficiency), with conflicting results in terms of performance. Therefore, the aim of the present article was to review the theoretical background of noncircular chainrings and novel pedal to crank interfaces and their effects on biomechanical, physiological and performance variables. Reducing internal work, crank peak torque, and time spent at the top and bottom dead centres (12 o'clock and 6 o'clock positions, respectively) were among the various targets of noncircular chainrings and novel pedal to crank interface design. Changes in joint kinematics without effects on muscle activation were observed when cyclists were assessed using noncircular chainrings and novel pedal to crank interfaces. Conflicting results for economy/efficiency explain the unclear effects of noncircular chainrings on cycling performance and the positive effects of some novel pedal to crank interfaces on cycling economy/efficiency.

O objetivo deste estudo foi comparar a cinemática de pedalada em ciclistas de duas modalidades diferentes (estrada e mountain-bike). A aquisição dos dados foi feita usando o sistema Peak Motus, sendo analisado o comportamento angular da coxa, joelho e tornozelo enquanto os ciclistas pedalaram em intensidade relativa ao segundo limiar ventilatório. Os resultados foram analisados estatisticamente com teste t de Student a cada 30º do pé-de-vela, não mostrando diferenças entre as modalidades. Entretanto, a cinemática do tornozelo apresentou grande variabilidade. A característica encontrada para o tornozelo possivelmente seja um fator decisivo para diferenças na técnica de pedalada entre os ciclistas destas duas modalidades, em relação à aplicação das forças no pedal.

The purpose of this study was to compare the pedaling kinematics of cyclists of two different disciplines (road and mountain-bike). Data collection and analysis were accomplished using the Peak Motus System, and the angular kinematics behavior for the thigh, knee and ankle were analyzed while the cyclists pedaled in relative intensity to the second ventilatory threshold. The results were statistically compared by Student’s t-test to every 30° of crank, showing no statistically differences among the cycling disciplines. However, the ankle kinematics presented high variability. This characteristic found for the ankle may be a decisive factor related to the differences in the pedaling technique among cyclists of these two disciplines.