A biomechanical comparison of different baseball batting training methods

This study compared the kinematic parameters of swing mechanics under toss batting (TB), motor imagery (MI), video projection (VP), and virtual reality (VR) conditions during baseball batting. Nine college baseball players performed three swings to hit a tossed ball under TB conditions or a virtual ball under MI, VP, and VR conditions. The results revealed that upper trunk backward rotation was smaller in the loading phase under the VP and VR conditions than under the TB and MI conditions and lower under VR than under the VP condition ( p < 0.05) except at the load event. Pelvic backward rotation was smaller under the VR condition than under the TB, MI, and VP conditions ( p < 0.05). In the swing phase, TB demonstrated higher peak velocity at the head of the bat, lead elbow extension, and pelvis and upper trunk rotation than did MI, VP, and VR, whereas VP also demonstrated higher peak velocity in pelvic forward rotation than did VR ( p < 0.05). In summary, VR demonstrates a more realistic response in the loading phase and reduced pelvic backward rotation but lower movement velocities. Coaches should pay attention to movement differences between swing conditions when arranging a swing training plan.

IMU-Based Effects Assessment of the Use of Foot Orthoses in the Stance Phase during Running and Asymmetry between Extremities

The objectives of this study were to determine the amplitude of movement differences and asymmetries between feet during the stance phase and to evaluate the effects of foot orthoses (FOs) on foot kinematics in the stance phase during running. In total, 40 males were recruited (age: 43.0 ± 13.8 years, weight: 72.0 ± 5.5 kg, height: 175.5 ± 7.0 cm). Participants ran on a running treadmill at 2.5 m/s using their own footwear, with and without the FOs. Two inertial sensors fixed on the instep of each of the participant’s footwear were used. Amplitude of movement along each axis, contact time and number of steps were considered in the analysis. The results indicate that the movement in the sagittal plane is symmetric, but that it is not in the frontal and transverse planes. The right foot displayed more degrees of movement amplitude than the left foot although these differences are only significant in the abduction case. When FOs are used, a decrease in amplitude of movement in the three axes is observed, except for the dorsi-plantar flexion in the left foot and both feet combined. The contact time and the total step time show a significant increase when FOs are used, but the number of steps is not altered, suggesting that FOs do not interfere in running technique. The reduction in the amplitude of movement would indicate that FOs could be used as a preventive tool. The FOs do not influence the asymmetry of the amplitude of movement observed between feet, and this risk factor is maintained. IMU devices are useful tools to detect risk factors related to running injuries. With its use, even more personalized FOs could be manufactured.

PROBLEM SOLVING BY EXPERTS AND NOVICES IN CHEMISTRY: ANALYSIS OF ERRORS, RUN TIMES AND PARAMETERS OF EYE MOVEMENTS

Background. Professional experience is one of the most discussed problems in modern labor psychology. Researchers are trying to expose and describe the system of cognitive and metacognitive skills and abilities, which gives an advantage to experienced professionals. However, there is still a sufficient number of contradictions and unexplored aspects. The aim of the study is to identify specific features of problem solving by chemists at different levels of professional experience by analyzing performance indicators and eye movements. Techniques and sampling. The pilot study involved 35 experts and novices in the field of chemistry. They were asked to read descriptions, find errors and fill in gaps in chemical process diagrams. The tasks were based on technological regulations for the production of chemical products. We recorded the run time, errors and indicators of eye movements with the SMI Hi-Speed contactless video recording system with a 1200 Hz frequency. The results showed that the run time and the number of errors were significantly lower for experts than for novices. In addition, the two groups featured significant differences in the average duration of blinking, indicating a higher emotional stress among novices. Other eye movement differences demonstrated that experts tend to favor focal type of cognitive processing. This is revealed in longer fixations, short and slow saccades. Also, the experts were characterized by an uneven distribution of attention and cognitive efforts relative to different parts of the task and by a smaller number of transitions between them. The general analysis showed that experts, solving problems, rely more on mental representations and previous knowledge, while novices are guided by the information presented on the slides. Conclusions. The data demonstrate the superiority of experts in solving chemical problems and reveal the cognitive structure of professional experience.

The interplay between movement, morphology and dispersal in Tetrahymena ciliates

Understanding how and why individual movement translates into dispersal between populations is a long-term goal in ecology. Movement is broadly defined as ‘any change in the spatial location of an individual’, whereas dispersal is more narrowly defined as a movement that may lead to gene flow. Because the former may create the condition for the latter, behavioural decisions that lead to dispersal may be detectable in underlying movement behaviour. In addition, dispersing individuals also have specific sets of morphological and behavioural traits that help them coping with the costs of movement and dispersal, and traits that mitigate costs should be under selection and evolve if they have a genetic basis. Here, we experimentally study the relationships between movement behaviour, morphology and dispersal across 44 genotypes of the actively dispersing unicellular, aquatic model organism Tetrahymena thermophila. We used two-patch populations to quantify individual movement trajectories, as well as activity, morphology and dispersal rate. First, we studied variation in movement behaviour among and within genotypes (i.e. between dispersers and residents) and tested whether this variation can be explained by morphology. Then, we addressed how much the dispersal rate is driven by differences in the underlying movement behaviour. Genotypes revealed clear differences in terms of movement speed and linearity. We also detected marked movement differences between resident and dispersing individuals, mediated by the genotype. Movement variation was partly explained by morphological properties such as cell size and shape, with larger cells consistently showing higher movement speed and higher linearity. Genetic differences in activity and movement were positively related to the observed dispersal and jointly explained 47% of the variation in dispersal rate. Our study shows that a detailed understanding of the interplay between morphology, movement and dispersal may have potential to improve dispersal predictions over broader spatio-temporal scales.

The interplay between movement, dispersal and morphology in Tetrahymena ciliates

Understanding how and why individual movement translates into dispersal between populations is a long-term goal in ecology. Movement is broadly defined as “any change in the spatial location of an individual”, whereas dispersal is more narrowly defined as a movement that may lead to gene flow. Because the former may create the condition for the latter, behavioural decisions that lead to dispersal may be detectable in underlying movement behaviour. In addition, dispersing individuals also have specific sets of morphological and behavioural traits that help them coping with the costs of movement and dispersal, and traits that mitigate costs should be under selection and evolve if they have a genetic basis. Here we experimentally study the relationships between movement behaviour, morphology and dispersal across 44 genotypes of the actively dispersing unicellular, aquatic model organism Tetrahymena thermophila. We used two-patch populations to quantify individual movement trajectories, as well as activity, morphology and dispersal rate. First, we studied variation in movement behaviour among and within genotypes (i.e. between dispersers and residents) and tested whether this variation can be explained by morphology. Then, we address how much the dispersal rate is driven by differences in the underlying movement behaviour. Genotypes revealed clear differences in terms of movement speed and linearity. We also detected marked movement differences between resident and dispersing individuals, mediated by the genotype. Movement variation was partly explained by morphological properties such as cell size and shape, with larger cells consistently showing higher movement speed and higher linearity. Genetic differences in activity and diffusion rates were positively related to the observed dispersal and jointly explained 47% of the variation in dispersal rate. Our study shows that a detailed understanding of the interplay between morphology, movement and dispersal may have potential to improve dispersal predictions over broader spatio-temporal scales.