EFFICIENCY OF OVERARM THROWING

The term "Mechanical Efficiency" Is commonly used In the discussion of Biomechanics. And a lot of studies as for mechanical efficiency have been made on the relationship betreen work performed and corresponding enery cost in such fundamental movements as walking (Margarla 1963, Cavagna and Kaneko 1977), running (Cavagna et al. 1966, DI Prampero 1974) and blcycilng (Garry and Whishart 1934, Whlpp and Wasserman 1969). However, little was reported concerning mechanical efficiency of overarm throwing movement patterns used in Baseball, Team Handball and Basketball, and to discuss the relationship between the mechanical efficiency and three different types of throwing movement patterns from the point of ball size and weight

Presetting of the Corticospinal Excitability in the Tibialis Anterior Muscle in Relation to Prediction of the Magnitude and Direction of Postural Perturbations

The prediction of upcoming perturbation modulates postural responses in the ankle muscles. The effects of this prediction on postural responses vary according to predictable factors. When the amplitude of perturbation can be predicted, the long-latency response is set at an appropriate size for the required response, whereas when the direction of perturbation can be predicted, there is no effect. The neural mechanisms underlying these phenomena are poorly understood. Here, we examined how the corticospinal excitability of the ankle muscles [i.e., the tibialis anterior (TA), the soleus (SOL), and the medial gastrocnemius (MG), with a focus on the TA], would be modulated in five experimental conditions: (1) No-perturbation; (2) Low (anterior translation with small amplitude); (3) High (anterior translation with large amplitude); (4) Posterior (posterior translation with large amplitude); and (5) Random (Low, High, and Posterior in randomized order). We measured the motor-evoked potentials (MEPs) induced by transcranial magnetic stimulation (TMS) at 50 ms before surface-translation in each condition. The electromyographic (EMG) responses evoked by surface-translations were also measured. The results showed that the TA-MEP amplitude was greater in the High condition (where the largest TA-EMG response was evoked among the five conditions) compared to that in the No-perturbation, Low, and Posterior conditions (High vs. No-perturbation, p < 0.001; High vs. Low, p = 0.001; High vs. Posterior, p = 0.001). In addition, the MEP amplitude in the Random condition was significantly greater than that in the No-perturbation and Low conditions (Random vs. No-perturbation, p = 0.002; Random vs. Low, p = 0.002). The EMG response in the TA evoked by perturbation was significantly smaller when a perturbation can be predicted (predictable vs. unpredictable, p < 0.001). In the SOL and MG muscles, no prominent modulations of the MEP amplitude or EMG response were observed, suggesting that the effects of prediction on corticospinal excitability differ between the dorsiflexor and plantar flexor muscles. These findings suggest that the corticospinal excitability in the TA is scaled in parallel with the prediction of the direction and magnitude of an upcoming perturbation in advance

BIOMECHANICAL CONSIDERATIONS OF CMJ AND SQJ ON THE SAFETY MAT

The purpose of this study was to detect whether differences exist concerning the kinematic parameters of jump (SQJ and CMJ) on two different surfaces (RS and SS). Nine healthy students performed two jumps on two surfaces. Two factor repeated measure (ANOVA) was used for statistical analysis (

BATTING AND BUTTON-PRESS REACTION TIME IN PRIMARY, JUNIOR HIGH AND HIGH SCHOOL BASEBALL PLAYERS

The focus of this study was how baseball players acquire rapid visuo-motor processing during developmental stages. We compared simple and Go/Nogo reaction times in a button-press task and a swing-a-bat task between different age groups of teenage baseball players. Though reaction time, swing time and total reaction time were shorter in the older group, baseball-specific visuo-motor skills could not be investigated by our experiment. These results indicate that the general neural foundations underlying baseball performance develop over the school years

Investigating the gaze control ability of VALORANT players using a Python based tool

The current study investigated the gaze movements of FPS gamers in actual game environments. We developed a low-cost analysis tool using Python to identify gaze movements in real-world gaming environments. In Experiment 1, 11 middle-skilled and ten high-skilled FPS gamers performed a task under the experimental condition. Gaze position, reaction time, and accuracy were calculated during the task. Reaction time exhibited a significant positive correlation with task accuracy, suggesting that speed and accuracy were associated with higher game performance. The middle-skilled gamers had a significantly wider horizontal gaze distribution than the high-skilled gamers, and gaze distribution and reaction time showed a negative correlation. These results suggested that high-skilled players utilize peripheral vision during gameplay. In Experiment 2, 15 middle-skilled and 12 high-skilled FPS gamers performed an actual FPS game match. The gaze distribution, kill/death/assist ratio (KDA), and percentage of gaze on game information were calculated. In experiment 2, gaze locations in less important areas were positively correlated with KDA. Thus, performance was determined by the important areas where the gaze was focused rather than by the coordination of gaze position alone. Therefore, a broader range of environments is necessary to comprehend the superior performance of FPS gamers.Comment: 8 Pages, 8 figures, submitted in IEEE Transactions on Game

Neural effects of muscle stretching on the spinal reflexes in multiple lower-limb muscles

While previous studies have shown that muscle stretching suppresses monosynaptic spinal reflex excitability in stretched muscles, its effects on non-stretched muscles is still largely unknown. The purpose of this study was to examine the effects of muscle stretching on monosynaptic spinal reflex in non-stretched muscles. Ten healthy male subjects participated in this study. Muscle stretching of the right triceps surae muscle was performed using a motor torque device for 1 minute. Three different dorsiflexion torques (at approximately 5, 10, and 15 Nm) were applied during muscle stretching. Spinal reflexes evoked by transcutaneous spinal cord stimulation were recorded in both the lower-limb muscles before, during, and at 0 and 5 min following muscle stretching. The amplitudes of the spinal reflexes in both the stretched and non-stretched muscles in the right (ipsilateral) leg were smaller during stretching compared to before, and at 0 and 5 min after stretching. Furthermore, the degree of reduction in the amplitude of the spinal reflexes in the right (ipsilateral) leg muscles increased significantly as the dorsiflexion torque (i.e., stretching of the right triceps surae muscles) increased. In contrast, reduction in the amplitude of the spinal reflexes with increasing dorsiflexion torque was not seen in the left (contralateral) leg muscles. Our results clearly indicate that muscle stretching has inhibitory effects on monosynaptic spinal reflexes, not only in stretched muscles, but also in non-stretched muscles of the ipsilateral leg

Corticospinal excitability is modulated as a function of postural perturbation predictability

Recent studies demonstrated that the corticospinal pathway is one of the key nodes for the feedback control of human standing and that the excitability is flexibly changed according to the current state of posture. However, it has been unclear whether this pathway is also involved in a predictive control of human standing. Here, we investigated whether the corticospinal excitability of the soleus (SOL) and tibialis anterior (TA) muscles during standing would be modulated anticipatorily when perturbation was impending. We measured the motor-evoked potential (MEP) induced by transcranial magnetic stimulation over the motor cortex at six stimulus intensities. Three experimental conditions were set depending on predictabilities about perturbation occurrence and onset: No perturbation, No Cue, and Cue conditions. In the Cue condition, an acoustic signal was given as timing information of perturbation. The slope of the stimulus–response relation curve revealed that the TA-MEP was enhanced when postural perturbation was expected compared to when the perturbation was not expected (No Perturbation vs. No Cue, 0.023 ± 0.004 vs. 0.042 ± 0.007; No Perturbation vs. Cue, 0.023 ± 0.004 vs. 0.050 ± 0.009; Bonferroni correction, p = 0.01, respectively). In addition, two-way analysis of variance (intensity × condition) revealed the main effect of condition (F(1,13) = 6.31, p = 0.03) but not intensity and interaction when the MEP amplitude of the Cue and No Cue conditions was normalized by that in No Perturbation, suggesting the enhancement more apparent when timing information was given. The SOL-MEP was not modulated even when perturbation was expected, but it slightly reduced due to the timing information. The results of an additional experiment confirmed that the acoustic cue by itself did not affect the TA- and SOL-MEPs. Our findings suggest that a prediction of a future state of standing balance modulates the corticospinal excitability in the TA, and that the additional timing information facilitates this modulation. The corticospinal pathway thus appears to be involved in mechanisms of the predictive control as well as feedback control of standing posture

Influence of amplitude regarding finger force on loudness discrimination acuity of self-generated sound

International audienc

FACTORS AFFECTING FREE THROWING

Every basketball player has an appetite to increase the free throw shooting performance. Sometimes the game depends upon their success shots. But it is difficult for basketball players to improve their own performance because, to do so, there are some factors such as good timing of muscle activity and mechanical efficiency. Especially relating to mechanical efficiency, it was investigated in various physical movements. As a result, previous study indicated that mechanical efficiency was an important index to "skill". However, it has not been reported about its improvement in conjunction with training. Therefore, the purpose of this study was to determine the mechanical efficiency of free throw shooting exercise in basketball, and assess the improvement of mechanical efficiency and performance through an eight week training program

BIOMECHANICAL CONSIDERATIONS OF TAKEUMA-WALKING IN WATER

"TAKEUMA" is one of Japanese classic style of playing. Usually it is played on land, but in water, one can easier ambulate with TAKEUMA in water, for buoyancy and resistance force. The purposes of this study were to clarify biomechanical features of TAKEUMA-walking in water and to compare the motion characteristics of skilled TAKEUMA players with those of unskilled. The TAKEUMA-walking motions were recorded both in a water tank and on land. It was revealed that the body inclination to the forward direction would be a key feature of the well-trained TAKEUMA-walking, and even in unskilled subjects the relatively greater forward-inclined posture was preserved in water. It is important to handle and hold a TAKEUMA by using upper limbs, especially forearms, when walking with TAKEUMA in water