A topspin rate exceeding 110 rps reduces the ball time of arrival to the opponent: a table tennis rally study.

This study experimentally investigated the factors affecting the time a table tennis ball with topspin takes to reach the opponent. Six skilled young players and one coach performed topspin forehand strokes under the observation of three high-speed cameras. As the distribution of the participants' measurements was uneven, additional data were collected using a launching machine that could control the ball speed and spin. To verify the effect of the spin rate on speed decay by drag, the translational speed was measured at 0.15 s after passing the baseline (23 m/s); the balls with topspin ≥110 rps, close to participants' average (117 ± 29 rps) were 1.4 m/s faster than those with topspin ≤80 rps. The horizontal ball speed changed in the range of -3.1 to 2.6 m/s owing to table bounce. At topspins ≥110 rps the ball reached a point 1 m past the end line (estimated receiving position) 27 ± 5 ms faster than at topspins ≤80 rps, for the same initial speed. The relationship between spin rate and travel time was non-linear with boundaries at 80 and 110 rps. Therefore, maintaining a spin rate of ≥ 110 rps along with a high initial speed is an effective strategy for reducing the opponent's preparation time.

Clarifying the Biomechanical Concept of Coordination Through Comparison With Coordination in Motor Control.

Coordination is a multidisciplinary concept in human movement science, particularly in the field of biomechanics and motor control. However, the term is not used synonymously by researchers and has substantially different meanings depending on the studies. Therefore, it is necessary to clarify the meaning of coordination to avoid confusion. The meaning of coordination in motor control from computational and ecological perspectives has been clarified, and the meanings differed between them. However, in biomechanics, each study has defined the meaning of the term and the meanings are diverse, and no study has attempted to bring together the diversity of the meanings of the term. Therefore, the purpose of this study is to provide a summary of the different meanings of coordination across the theoretical landscape and clarify the meaning of coordination in biomechanics. We showed that in biomechanics, coordination generally means the relation between elements that act toward the achievement of a motor task, which we call biomechanical coordination. We also showed that the term coordination used in computational and ecological perspectives has two different meanings, respectively. Each one had some similarities with biomechanical coordination. The findings of this study lead to an accurate understanding of the concept of coordination, which would help researchers formulate their empirical arguments for coordination in a more transparent manner. It would allow for accurate interpretation of data and theory development. By comprehensively providing multiple perspectives on coordination, this study intends to promote coordination studies in biomechanics.

Sequential change in serum VEGF levels in a case of tocilizumab-resistant TAFRO syndrome treated effectively with rituximab.

Recently, a unique clinicopathologic variant of multicentric Castleman disease, TAFRO (i.e. thrombocytopenia, anasarca, fever, renal failure or reticulin fibrosis and organomegaly) syndrome, has been identified in Japan. Previous reports have shown that affected patients usually respond to anti-interleukin 6 (IL-6) receptor antibody, but not all patients achieve remission. Here, we present a 62-year-old man meeting the criteria of TAFRO syndrome. Serum, plasma and ascites levels of cytokines, including IL-6 and vascular endothelial growth factor, were markedly elevated. Tocilizumab, an anti-IL-6 receptor antibody, and corticosteroids were initially used to treat the increase in acute inflammatory proteins and the anasarca, resulting in decreased cytokine levels. However, the patient showed a rapidly progressive course of anasarca and ascites, and an increase in acute inflammatory proteins and cytokine levels shortly thereafter. Rituximab, an anti-CD20 antibody, successfully induced remission of disease symptoms and decreased cytokine levels. The patient was successfully treated with rituximab despite being refractory to tocilizumab and corticosteroids. During our patient's clinical course, monitoring cytokine profiles, especially vascular endothelial growth factor, was useful in tracking the disease activity of TAFRO syndrome.

Disease activity and response to therapy monitored by [18F]FDG PET/CT using volume-based indices in IgG4-related disease.

PURPOSE: The efficiency of [18F]FDG PET/CT using volume-based indices was evaluated to assess the disease activity and response to therapy in patients with immunoglobulin G4-related disease (IgG4-RD). METHODS: A total of 17 patients with IgG4-RD were examined with [18F]FDG PET/CT before and during treatment. The lesion boundary was determined using a fixed threshold of standardized uptake value (SUV) ≥ 2.5. The highest maximum SUV (SUVmax) among all affected lesions was calculated for individual patients. We summed metabolic tumor volume (MTV) and total lesion glycolysis (TLG) of each affected lesion to generate a total MTV and total TLG. PET results were compared with those of serum IgG4 and soluble interleukin-2 receptor (sIL-2R) levels. RESULTS: The mean number of involved organs per patient was 3.8 as determined by [18F]FDG uptake. The number of involved organs, total MTV and total TLG were significantly correlated with IgG4 (P = 0.046, < 0.001, < 0.001, respectively) and sIL-2R (P < 0.001, = 0.031, 0.031, respectively). According to the clinical assessments for therapy response, all patients were classified as improved. The SUVmax, total MTV, and total TLG during therapy were all significantly lower than those before therapy (all P < 0.001). CONCLUSION: [18F]FDG PET/CT is valuable for assessing the extent of multi-organ involvement before therapy and monitoring subsequent therapy in patients with IgG4-RD. [18F]FDG PET/CT using volumetric indices correlated with serum IgG4 and sIL-2R levels.

Kinematics of Rugby Tackling: A Pilot Study With 3-dimensional Motion Analysis.

BACKGROUND: Although improper tackling technique in rugby can affect the outcome of the tackle and lead to head, neck, and shoulder injuries, the effects of the height of the tackle or the side of the leading leg at the time of impact have not been investigated. Hypothesis/Purpose: The purpose was to characterize the trunk orientation at impact during various tackles. It was hypothesized that 3-dimensional motion analysis would be able to capture the critical kinematic differences in the 4 types of tackles studied. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 66 tackles on a tackle bag were recorded among 13 elite rugby players. Four types of tackles were evaluated: the normal shoulder tackle, in which the tackler's dominant shoulder made impact while the leading foot was on the same side as that shoulder; the low tackle, in which the tackler targeted the lower portion of the tackle bag; the opposite-leg tackle, in which the tackler's leading leg was on the opposite side as the shoulder making impact; and the low and opposite-leg tackle, which was a combination of the previous 2 types of tackles. The orientation of the trunk at impact was calculated, and 2-way repeated-measures analyses of variance were used to compare the characteristics of these tackles. RESULTS: Trunk inclination at impact was lower in the low tackle than in the normal tackle ( P < .01), regardless of the side of the leading leg. Trunk bending to the side of the impacted shoulder was lower in the opposite-leg tackle ( P < .01), and these findings were more significant in the normal-height tackles ( P < .01). Trunk rotation to the side of the impacted shoulder was lower in the opposite-leg tackles ( P < .01) and more significant in the lower-height tackles ( P = .03). CONCLUSION: The 3-dimensional motion capture system was effective in investigating the kinematics of rugby tackling. The kinematics in the low and opposite-leg tackles were significantly different from those in the normal shoulder tackle, which may affect tackle performance and the possible risk of contact injury. CLINICAL RELEVANCE: When a rugby coach provides tackling instructions to players, it is advantageous to have information about the kinematics of different types of tackles.

Middle finger and ball movements around ball release during baseball fastball pitching.

The objectives of this study were to investigate middle finger movements and dynamics of ball movements around the instant of ball release during baseball pitching. Baseball pitching from an indoor mound among 14 semi-professional pitchers was captured using a motion capture system with 16 high-speed cameras (1,000 Hz). Kinematics of middle finger joints, ball rotation, and force applied to the ball were calculated. The proximal and distal interphalangeal joints continued to extend until the instant of ball release, then abruptly flexed. The abrupt flexion lasted for only several milliseconds, followed by a short extension phase. The finger made a quick double cycle of extension-flexion movement, suggesting that it attained high stiffness resulting from co-contraction. The ball began to roll up to the tip of the finger 8 ± 1 ms before ball release owing to the start of extension or the increased angular velocity of extension for the proximal interphalangeal joint. A mean force of 195 ± 27 N was applied in the proximal direction of the hand at the same time as the beginning of ball rolling, and a mean force of 109 ± 22 N was applied to the throwing direction just before ball release.

Effect of Changing Table Tennis Ball Material from Celluloid to Plastic on the Post-Collision Ball Trajectory.

The official material used in table tennis balls was changed from celluloid to plastic, a material free of celluloid, in 2014. The purpose of this study was to understand the differences and similarities in the two types of ball materials by comparing their behavior upon collision with a table. The behavior of the balls before and after collision with a table, at various initial speeds ranging from 15 to 115 km/h, was captured using high-speed cameras. Velocities and spin rates before collision and velocities after collision were computed to calculate the coefficients of restitution and friction. Based on the computed variables, the post-collision trajectories of both balls were calculated by integrating the equation of motion of the ball for simulated service, smash and drive conditions with respect to time. The coefficients of restitution were higher for the plastic balls than the celluloid ones when the initial vertical velocities were higher. The coefficients of friction were higher for plastic balls when the initial horizontal contact point velocities were slower. Because of the differences in the material characteristics, the plastic ball trajectories of services with backspin and drives with great topspin were expected to be different from those of celluloid balls. Since the extent of differences between the two ball types varied depending on the initial conditions, testing at various initial conditions was suggested for comparing and understanding the characteristics of the balls.

Radio-ulnar joint supinates around ball release during baseball fastball pitching.

This study was conducted to determine whether a supination phase of the forearm exists around ball release (BRL), and, if present, to determine whether this supination is explained by a reaction force or by the body configuration required for this task. A 16-camera motion analysis system with a sampling frequency of 1,000 Hz recorded 20 healthy male semi-professional pitchers pitching from an indoor pitching mound. A short supination phase around BRL was confirmed for all participants in the current study. Correlation analyses revealed that the supination angle at BRL had significant relationships with several measurements of shoulder movement kinematics. Mechanical work analysis of the forearm's longitudinal axis revealed several variations in joint power curve and various patterns of mechanical work among the participants, suggesting that a reaction force originating from accelerating a ball might not be the main cause of supination. The raw data also were down-sampled to a sampling frequency of 250 Hz, to match previous studies and to investigate the discrepancy among previous studies concerning the existence of the supination phase. The experience of participants and methodological differences, such as the definition of BRL and the time-normalisation technique, influenced whether the supination phase was observed.

DOES COLCHICINE AFFECT AGGREGATION OF NORMAL AND TRANSFORMED BHK CELLS DIFFERENTLY?

The effect of colchicine and vinblastine on cell aggregation was studied, using BHK cells and their transformed derivatives (pyBHK cells). When cells were dissociated with EDTA and the assay was made in a Ca2+ -containing medium, the aggregation of transformed cells was prevented by colchicine and vinblastine, whereas the aggregation of normal cells was unaffected. When a Ca2+ -free medium was used for aggregation, neither type of cell was influenced by these drugs. BHK and pyBHK cells, dissociated by trypsin in the presence of Ca2+ , can aggregate only in the Ca2+ -containing medium and the aggregation of both cell types was equally prevented by colchicine and vinblastine. Based on these results, it was concluded that colchicine and vinblastine inhibited the Ca2+ -dependent mechanism of cell adhesion, but not the Ca2+ -independent one which occurs in the Ca2+ -free aggregation medium.