Enhancing the successful jump-shot percentages in basketball is critical for winning a game. A selection of release parameters and variability can influence the success rate, but the actual selection of the release parameters and variabilities in those during jump shots and the influence of this selection on success rate have not been investigated and are not understood well. Thus, the purpose of this study was to investigate the influences of the selection of release angle, release speed and spin rate, and variability on the success rate of jump-shots in basketball. Ten male collegiate basketball players participated in the study and actual ball trajectories for the jump-shots from the free-throw (FT) and three-point (3P) lines were recorded by the three-dimensional motion analysis system. The experimental data was compared with the theoretical optimal release parameters. We found that the players with higher success rate in FT shots had a higher release position, a lower release velocity, and a larger margin for error for the release speed. On the other hand, for the 3P shots, the player with a larger margin for error for the combination of the release speed and angle had higher success rate. Variability in release parameters did not have significant correlation with the success rate. Thus, it can be said that selecting the release parameters that allow greater margin for error was important for increasing the success rate. Also, depending on the required release speed or the shooting distance, the strategies for the selection of the release parameters must be adjusted to increase the success rate in jump-shots.
This study aimed to examine the relationship between the trunk impairment level and the trunk kinematic characteristics during alpine sit-skiing from a classification perspective. Three Paralympic medalists in sitting classes (LW10-2, LW11, and LW12-2) participated in the present study. To simulate the racing conditions, giant slalom gates were set. To measure the kinematics of the skier and sit-ski during skiing, a motion capture method with inertial measurement units was used. The muscle activities of the trunk muscles were evaluated using electromyography. Chest lateral flexion, chest flexion, and hip flexion/extension angle during sit-skiing were reduced due to impairment. Additionally, the insufficient lateral flexion (angulation) caused a decrease in edging angle, and that the insufficient chest and hip flexion/extension caused a lower loading in the latter half of the turn through smaller vertical movement. Since edging angle and loading are key factors in ski control, the three joint motions could be measures of sport-specific activity limitation in sit-skiing classification. Between the LW10-2 and LW11 skiers, no distinct differences in trunk kinematics were found. Assuming the scaling factor of race time as a measure of skiing performance, one possible reason is that the difference in skiing performance the LW10-2 and LW11 skiers is considerably smaller relative to differences between the LW11 and LW12-2 skiers. There were no distinct differences among classes in the results of muscle activity, and therefore, this information appears to play a minimal role for classification.
The purpose of this study was to investigate the characteristics of running on selfdriven treadmill equipped with curve-shaped bed (TM) from kinematics and kinetics variables by comparing with those obtained on overground running (OG). Eight healthy male subjects run on TM and OG under constant speed condition of 3m/s. Thirty five reflective anatomical landmarkers were attached on the subject according to Plug-in-gait model. Kinematics and kinetics data were recorded during stance phase using VICON MX (200fps) motion capture system and Kistler force plate (1kHz). Running spatio-temporal parameters such as stride length /stride frequency, lower limb joint kinematics and ground reaction force were compared between TM and OG conditions. Significant high stride frequency on TM running was indicated compare with OG condition (P<0.05). Contact time were almost same between TM and OG, whereas in vertical ground reaction force, non-first impact force as well as lower average loading rate were indicated in TM compared to OG (P<0.05). Lower joint kinematics were significantly different between TM and OG running during first 20% stance phase of normalized stance time. Hip and knee flexion angular velocities were larger in OG than TM (P<0.05). These results suggest that TM running causes lowed intensity for lower limb joints during stance phase, which might be applicable for prevention of running injury.Jpn J Phys Fitness Sports Med, 64(3): 333-344 (2015)
The Tokyo 2020 Olympics and Paralympic Games were held in the hottest environment in the history of the games. Additionally, the worldwide coronavirus disease 2019 (COVID-19) pandemic necessitated daily polymerase chain reaction (PCR) testing during the games, wearing a mask became mandatory publicly, and it was an unheard and unique Olympic with no spectators. Heat acclimation, hydration, and body cooling are essential for safe and high-performance activities in hot environments. In 2015, the Japan Institute of Sports Sciences launched the “Heat Countermeasure Project” to conduct experiments and practical research on heat countermeasures and investigate issues related to heat countermeasures in each athletic event. The results obtained were proposed to various Japan national sports teams, and support for heat countermeasures for the Tokyo 2020 games was promoted in consultation with national federations. Furthermore, due to the COVID-19 pandemic, infectious disease countermeasures for the Tokyo 2020 Games during support were a must. Moreover, athletes, coaches, and team staff could not avoid implementing heat countermeasures while adopting measures against infectious diseases. This study aimed to clarify the issues faced with heat countermeasures and report on heat acclimation training and cooling support efforts, considering measures against infectious diseases.
Introduction:In the past, body segmental volume was measured from various methods as immersion method, mathematical model, photogrammetric, have been used for various research in biomechanics. As for the three dimensional anthropometry how there are a whole body volume and each segment volumes, possibility of estimation of various body segment parameter will be shown. Purpose of this study was estimated center of mass using three dimensional anthropometry. Methods: The subjects were 6 males (Age:22.3±1.1 years, body height: 172.5±5.9cm, body mass: 67.2±2.5kg) participated in this study. We used Body line scanner ( BLS: Hamamatsu Photonics KK) for 3D Whole body anthropometry. Subjects were measured a whole body volume using BLS. Scanning data obtained from BLS was distributed 14 parts of each segmental volumes using anatomical randmarkpoint, be calculated each segmental volumes. For the definition of each segment were used from C.E.Clauser,1969. Center of each segmental mass (SCOM) was calculated from each segmental volume. Segment mass (SM) was calculated using each segment density which from preceding study. Center of gravity (COG ABS ) and COG REL (center of gravity expressed as a percentage of the body height) was calculated from SCOM and SM of each segment. For the measurement of the COG ABS and COG REL , the reaction board method was employed. The reaction board consisted of a rigid board (180×91.5×2.5cm) mounted on a scale. COG ABS and COG REL were compared from each method that calculated from reaction board , BLS and predicted value from C.E.Clauser,1969 , and calculated %Difference. Results and Discussion: The whole body mass that we estimated using BLS compared with body weight, the difference was under 1.5%. %difference of COG ABS and COG REL (BLS and a measurement) were 2.9±0.9%, and the BLS showed lower than measurement (measured:COG ABS =97.2±3.6cm,COG REL =56.6±0.5%,BLS:COG ABS =94.4±3.0cm,COG REL =54.9±0.5%). In addition, the predicted value showed higher than a measurement (predicted value:COG ABS =100.1± 3.5cm,COG REL =58.3±0.6%). Conclusion: It was suggested that We can estimate COG which we estimated from segment mass and center of volume with an measured and a difference of 2.9% .
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