EFFECTS OF SEGMENTAL ROTATIONS ON VERTICAL AND HORIZONTAL ENERGIES DURING TAKE-OFF OF A LONG JUMP

This study aimed to reveal the effect of segmental rotation on the generation of vertical velocity and loss of horizontal velocity during take-off of a long jump. 3D motion capture system and force plates were used to capture the long jumps by nine male athletes with an approach running distance of approximately 20 m. Forward rotations of the shank and thigh of the stance leg increased vertical energy (Evert) and decreased horizontal energy (Ehori); however, elevation of the free leg side of the pelvis increased Evert (0.53 ± 0.16 J/kg), although pelvic elevation did not decrease Ehori (0.01 ± 0.02 J/kg). It was revealed that although shank and thigh movements involved the loss of horizontal velocity, elevation of the free leg side of the pelvis generated vertical velocity without the loss of horizontal velocity. This study provides evidence for a new technical approach for a long jump

UNCONTROLLED MANIFOLD ANALYSIS OF JOINT ANGLE VARIABILITY DURING TABLE TENNIS FOREHAND

The purpose of this study was to evaluate the variance structure of the trunk and racket arm joint angles in the table tennis topspin forehand in relation to the control of racket orientation using the uncontrolled manifold (UCM) approach. Seventeen (9 advanced and 8 intermediate) male collegiate table tennis players performed the strokes against backspin. The UCM analysis was conducted using 30 trial data per each participant. The degree of redundancy exploitation to stabilize the racket vertical and horizontal angles were not significantly different between the two performance levels, suggesting that the ability to exploit joint configuration redundancy may not contribute to achieving higher performance in sport hitting skill. The degree of redundancy exploitation is highest at ball impact and this result may reflect that the table tennis forehand is a fast interceptive task

EFFECT OF MECHANICAL PROPERTIES OF THE LOWER LIMB MUSCLES ON MUSCULAR EFFORT DURING TABLE TENNIS FOREHAND

The purpose of this study was to investigate the effect of the maximum isometric forces and the maximum shortening velocities of the lower limb muscles on the muscular effort during the table tennis forehand. Four male collegiate players performed table tennis forehand drives with maximum effort. We used OpenSim’s static optimization algorithm to estimate the activation patterns of lower limb muscles. The cost function was the sum of squared muscle activations for all lower limb muscles, which we will refer to as the muscular effort. The simulations were repeated with the maximum isometric forces or the maximum shortening velocities of each muscle group changed by ±10% of their original values. The results suggest that increasing the maximum isometric forces of the hip extensors and adductors may be most effective to reduce the muscular effort

VARIABILITY OF RELEASE PARAMETERS IN BASKETBALL FREE THROW

The aim of this study is to clarify what kind of variability of release parameters is associated with shot accuracy in basketball free-throw. Eight male right-handed basketball players in college team participated in this study. Participants made 50 shots from the free-throw line after warm-up. A 16-camera motion capture system was used to record the coordinates of the reflective markers attached on the participants’ bodies and the ball. The ball release parameters (i.e. release speed, angle and position) were calculated for the ball at the time of release. TNC-analysis that quantifies Tolerance, Noise, and Covariation cost of a performance (Cohen & Sternad, 2009; Sternad et al., 2011) and a correlation analysis were used to analyse the variability of release parameters. Our results showed that the value of C-cost is smaller for the participant whose shot probability of success was high. Our results suggest that learning various patterns of success in training may be efficient for improvement in free-throw

THE DIFFERENCES IN THREE-DIMENSIONAL KINETICS IN LOWER LIMB JOINTS OF SPRINTERS AND NOVICE RUNNERS DURING A START DASH

The purpose of this study was to clarify the differences in the three-dimensional joint moments of lower limbs between sprinters and novice runners. A total of 12 male sprinters and 11 healthy male college students participated in a start-dash experiment. At pushing the front starting block, in hip joint, extension moment of sprinters was significantly greater than that of novices. On the other hands, in ankle joint, not only the plantarflexion moments but also the inversion moment of sprinters was significantly greater than those of novices. Moreover, the peak value of the plantarflexion moment was positively correlated with that of the inversion moment. These results suggest that the greater ankle flexion-extension moment is achieved by coordinating with the greater inversion moments when attempting to increase acceleration ability

Kinetic analysis of fingers during fastball and curveball pitches

This study aims to reveal the function of fingers during fastball (FB) and curveball (CB) pitches of a male adult who had played university baseball pitcher by conducting kinetic analysis on throwing motion with a link-segment model including finger segment. There was no apparent difference in the timing of peak finger joint angle between FB and CB pitches. Peak finger adduction toque in CB pitch occurred just More ball release. In addition, there was an apparent difference more than 30 ms in the timing of peak finger flexion and abduction toque between FB and CB pitches. Previous comparisons of kinematic data for shoulder and elbow revealed similarities between FB and CB pitches. These results suggest that skilled pitcher may minimize visible distinguishing characteristics among pitches and generate different amounts of ball spin at release among pitches adjusting the timing of peak finger torque

Biomechanical analysis of the relation between movement time and joint moment development during a sit-to-stand task

<p>Abstract</p> <p>Background</p> <p>Slowness of movement is a factor that may cause a decrease of quality of daily life. Mobility in the elderly and people with movement impairments may be improved by increasing the quickness of fundamental locomotor tasks. Because it has not been revealed how much muscle strength is required to improve quickness, the purpose of this study was to reveal the relation between movement time and the required muscle strength in a sit to stand (STS) task. Previous research found that the sum of the peak hip and knee joint moments was relatively invariant throughout a range of movement patterns (Yoshioka et al., 2007, Biomedical Engineering Online 6:26). The sum of the peak hip and knee joint moment is an appropriate index to evaluate the muscle strength required for an STS task, since the effect of the movement pattern variation can be reduced, that is, the results can be evaluated purely from the viewpoint of the movement times. Therefore, the sum of the peak hip and knee joint moment was used as the index to indicate the required muscle strength.</p> <p>Methods</p> <p>Experimental kinematics data were collected from 11 subjects. The time at which the vertical position of the right shoulder fell outside three standard deviations of the vertical positions during the static initial posture was regarded as the start time. The time at which the vertical position fell within three standard deviations of the vertical positions during static upright standing posture was regarded as the finish time. Each movement time of the experimental movements was linearly lengthened and shortened through post-processing. Combining the experimental procedure and the post-processing, movements having various movement patterns and a wide range of movement times were obtained. The joint moment and the static and inertial components of the joint moment were calculated with an inverse dynamics method. The static component reflects the gravitational and/or external forces, while the inertial component reflects the acceleration of the body.</p> <p>Results</p> <p>The quantitative relation between the movement time and the sum of the peak hip and knee joint moments were obtained. As the STS movement time increased, the joint moments decreased exponentially and converged to the static component (1.51 ~ 1.54 N.m/kg). When the movement time was the longest (movement time: 7.0 seconds), the joint moments (1.57 N.m/kg) closely corresponded to the minimum of 1.53 N.m/kg as reported by Yoshioka et al..</p> <p>Conclusion</p> <p>The key findings of this study are as follows. (1) The minimum required joint moment for an STS task is essentially equivalent to the static component of the joint moment. (2) For fast and moderate speed movements (less than 2.5 seconds), joint moments increased exponentially as the movement speed increased. (3) For slow movements greater than 2.5 seconds, the joint moments were relatively constant. The results of this STS research has practical applications, especially in rehabilitations and exercise prescription where improved movement time is an intended target, since the required muscle strength can be quantitatively estimated.</p

THE CHALLENEGE OF NEW APPROACHES IN BIOMECHANICS

The target of our biomechanical research is to analyze the mechanics of motion, focusing especially on the behavior of the muscle-tendon complex during dynamic human movements. In our quest to better understand human motion, we have developed the several research methodologies. In the keynote lecture, I will discuss some of the techniques we have used and what we have learned from them. Specifically I will focus on the following: 1. Ultrasonography 2. Computer Simulation 3. Optical vs Inertial Sensor Analysis

DIFFERENT EFFECTS OF APPROACH LENGTH ON SAGITTAL AND FRONTAL JOINT KINETICS DURING A RUNNING SINGLE-LEG JUMP

The approach lengths in running single-leg jumps (RSLJs) vary depending on various sports. We examined the effects of approach length on joint kinetics in RSLJ. We analysed RSLJs for height from the approaches of 1, 3, 5, and 7 steps by 10 male jumpers. The approach length did not have a main effect on hip extension torque (from 3.18±0.46 to 3.41±0.65 Nm/kg), while the hip abduction torque increased with increase in approach length (from 1.84±0.38 to 2.62±0.66 Nm/kg). The lumbosacral lateral flexors behaved similarly to the hip abductors. Results suggest that the greater frontal torques must be exerted from longer approaches whereas the greater hip extensors are important for RSLJs from shorter approaches. The findings provide the information for athletes what torque exertion ability should be trained with a priority depending on their approach lengths