THE ADAPTIVE SSC: FROM FATIGUE RUNS ON EARTH TO THE REBOUNDS ON MARS

In natural forms of ground locomotion such as running and jumping, the functional phases include the stretching of the preactivated muscles followed by their shortening. This is called stretch-shortening cycle (SSC). SSC is a natural but complex activity that combines the available structuro-functional resources: the contractile and elastic structures with the central and reflex activation patterns. SSC may thus be used as a model to reveal the neural adjustments and the associated muscle-tendon responses to internal and external constraints. This presentation will focus on the neuro-mechanical adjustments to the acute and delayed SSC fatigue effects and to partial unweighting on lower body positive pressure treadmill. Both testing conditions emphasize the adaptive quality of the SSC, and demonstrate Time-, Task- and SSC phase-dependent neuro-mechanical adjustments

IDENTIFICATION OF STRETCH-SHORTENING CYCLES IN DIFFERENT SPORTS

In sports the stretch-shortening cycle (SSC) muscle actions are obviously natural. They are partly responsible for making the muscular performance more economical and/or better as compared to the use of isolated forms of muscle actions. In sport activities SSC can be traditionally identified by certain kinematic and electromyographic methods. An attempt is made to describe how one can go beyond these more simple ways by applying portable ultrasonography (US) to record fascicle-tendon interactions during various movements ranging in intensity from low to maximum. The observed results from a number of studies indicate that the original definition of SSC cannot be used to describe the SSC at the MTU levels of all muscles and all exercise conditions. However, the greatest merit of this US application is in its strength to explain more of the mechanism how the fascicle-tendon interaction differs between muscles and how the elastic energy may be involved in the performance potentiation

RELATION BETWEEN RELEASE PARAMETERS AND THROWING DISTANCE OF THE JAVELIN THROW

The present study was clarified a three-dimensional examination of the relation between the release parameters and throwing distances, in order to understand the initial flight characteristics of javelins. The subjects were 57 right-handed javelin throwers. The measured throwing distances ranged from 45.25 m to 87.17 m. The elite throwers had tendency to significant positive correlation between theoretical distance and initial velocity of javelin release. Throwers who achieved throwing distances of over 70m were observed to have throwing distances that were shorter than their theoretical distances, while those whose throwing distances were under 70 m group had throwing distances that were longer than their theoretical distances. When the data were applied to initial velocity of javelin release, it was equivalent to 26 m/s

Solar horizontal flow evaluation using neural network and numerical simulation with snapshot data

We suggest a method that evaluates the horizontal velocity in the solar photosphere with easily observable values using a combination of neural network and radiative magnetohydrodynamics simulations. All three-component velocities of thermal convection on the solar surface have important roles in generating waves in the upper atmosphere. However, the velocity perpendicular to the line of sight (LoS) is difficult to observe. To deal with this problem, the local correlation tracking (LCT) method, which employs the difference between two images, has been widely used, but LCT has several disadvantages. We develop a method that evaluates the horizontal velocity from a snapshot of the intensity and the LoS velocity with a neural network. We use data from numerical simulations for training the neural network. While two consecutive intensity images are required for LCT, our network needs just one intensity image at only a specific moment for input. From these input array, our network outputs a same-size array of two-component velocity field. With only the intensity data, the network achieves a high correlation coefficient between the simulated and evaluated velocities of 0.83. In addition, the network performance can be improved when we add LoS velocity for input, enabling achieving a correlation coefficient of 0.90. Our method is also applied to observed data.Comment: 13 pages, 20 figures, accepted for publication in pas

Interconversion of Two GDP-Bound Conformations and Their Selection in an Arf-Family Small G Protein

SummaryADP-ribosylation factor (Arf) and other Arf-family small G proteins participate in many cellular functions via their characteristic GTP/GDP conformational cycles, during which a nucleotide∗Mg2+-binding site communicates with a remote N-terminal helix. However, the conformational interplay between the nucleotides, the helix, the protein core, and Mg2+ has not been fully delineated. Herein, we report a study of the dynamics of an Arf-family protein, Arl8, under various conditions by means of NMR relaxation spectroscopy. The data indicated that, when GDP is bound, the protein core, which does not include the N-terminal helix, reversibly transition between an Arf-family GDP form and another conformation that resembles the Arf-family GTP form. Additionally, we found that the N-terminal helix and Mg2+, respectively, stabilize the aforementioned former and latter conformations in a population-shift manner. Given the dynamics of the conformational changes, we can describe the Arl8 GTP/GDP cycle in terms of an energy diagram

ARCHITECTURAL DIFFERENCES OF LOWER LIMB MUSCLE-TENDON FOR MONOZYGOTIC TWINS WITH DIFFERENT SPORT EXPERIENCES

The purpose of this study was to examine architectural differences of lower limb muscle-tendon for monozygotic twins with different sport experiences and for monozygotic twins with same sport experiences. 50 monozygotic twins (MZT) participated in this study, consisting of 16 MZT with different sport experiences, 34 MZT with same sport experiences. Musculoskeletal ultrasonography is applied to measure the muscle fascicle length of gastrocnemius medialis (GM) muscle as well as Achilles and patella tendon cross-sectional area (CSA) and length. Achilles tendon was separately measured from the AT insertion point on the calcaneus to the distal end of soleus muscle (ATSOL) and to the AT junction between medial and lateral gastrocnemii muscles (ATGML), respectively. The measured intraclass correlation coefficient (ICC) clearly showed poor concordances in the ATSOL length of MZT with different sport experiences (ICC of 0.74), and good concordance in the MG fascicle length of MZT with different sport experiences (ICC of 0.83). Other parameters in all intra-pears showed excellent concordances (ICC\u3e0.9). Thus, different concordances of AT length between GM and SOL parts can indicate the different plasticity by the structural and functional mechanics and different concordances between groups indicate that ATSOL and GM fascicle length are affected not only by genetic factors but also by acquired environmental factors