MECHANICAL PROPERTIES OF ACHILLES TENDON IN RELATION TO VARIOUS SPORT ACTIVITIES OF COLLEGIATE ATHLETES

The purpose of this study was to investigate whether mechanical properties of Achilles tendon adapt to the mechanics of diffrent sport activities. Subjects included thirty-five male collegiate track and field athletes (Sprinters, Long distance runners, Jumpers), swimmers, and non-athletes (Controls). The elongation of the Achilles tendon during isometric voluntary plantar flexion contraction was measured. Jumpers and swimmers displayed larger elongation, strain, tendon force and stress of the Achilles tendon when compared to long distance runners and controls. However, the stiffness and Young’s modulus of the Achilles tendon were not significantly different between groups. These results suggested that mechanical properties of the Achilles tendon were unchanged with load characteristics of each sport activity

NADase as a target molecule of in vivo suppression of the toxicity in the invasive M-1 group A Streptococcal isolates

<p>Abstract</p> <p>Background</p> <p>NAD-glycohydrolase (NADase) secreted by M-1 group A streptococcal (GAS) isolates are suspected as one of the virulence factors to cause severe invasive disease including streptococcal toxic shock-like syndrome (STSS). M-1 GAS strains were divided into three groups based on NADase activity: high activity, low activity and no activity in our previous report.</p> <p>Results</p> <p>The representative high activity isolates taken from STSS patients showed higher virulence compared with isolates from the low activity group, when used to infect mice. The knockout mutant of the <it>nga </it>gene, which encodes NADase also showed reduced virulence in a mouse infection study. The cloned <it>nga </it>gene was able to significantly complement the lost virulence. In addition, the solution containing purified recombinant IFS, which is an inhibitor of NADase, partially rescued mice infected with <it>S. pyogenes</it>.</p> <p>Conclusions</p> <p>These results indicate that NADase is important for the virulence of <it>S. pyogenes </it>in vivo and is the potential target to suppress the virulence.</p

GAZE AND STEP CONTROLS OF AN ELITE ATHLETE DURING APPROACHING DIFFERENT HURDLE HEIGHTS

This study investigated the gaze and step controls of one elite male hurdler when approaching hurdles at different heights. Across a 16 m runway, the participant performed three normal sprinting trials, and three hurdle running trials to clear a low, medium and high hurdle respectively. Gaze behaviour was captured using a mobile eye tracker that was mounted on the participant’s head and was filtered using a low-pass filter. In normal sprinting, the step length increased gradually from the first to eighth step. In the hurdle running trials, step length did not increase in the last step and fixations remained on the hurdle. The duration of fixations on the hurdle was lengthened by 21% and 44% in the middle and high hurdle trials, respectively, compared with the low hurdle trials. This pilot study provides foundational information on the interaction between gaze and hurdle running to clear hurdles of different heights that could potentially be optimized to improve performance in hurdling

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

FORWARD AND FALSE STEP TECHNIQUES USED FOR SPRINT START IN A SIDEWAYS DIRECTION: WHICH IS SUPERIOR?

The purpose of this study was to determine which technique is superior to in a standing sprint start in a sideways direction: the false step or forward step technique. Nine males performed 5 m sprints in a rightward direction starting with these two techniques. They took a first step in their right side with their right foot in the forward step trials, whereas they took a first step in their left side with their left foot in the false step trials. No significant differences were found between the two trial conditions in the sprint times for 1 m, 2 m, 3 m and 4 m. These results indicate that the start techniques made no difference in the performance in the sideways direction, although the superiority of the false step technique for the forward sprint start was reported previously. This finding suggests that the superiority of the sprint start techniques is dependent on the sprint direction

THE EFFECT OF HIP JOINT MUSCLE STRENGTH AND SIZE ON HIP JOINT ANGULAR VELOCITY DURING 110 M HURDLING MOTION

The purpose of this study was to investigate the effect of hip joint flexor/extensor strength andsize on hip joint angular velocity during 110 m hurdling motion. To achieve this goal, we determined hip joint angular velocity during hurdling motion with high speed camera. We also measured isokinetic hip joint torque with a dynamometer, and measured the muscle volume of the psoas major muscle and hamstrings of the lead leg side with MRI. There were significant correlations between isokinetic hip joint flexor torque at 0.52 and 1.05 rad/s and hip joint flexion angular velocity (p = 0.04 and p = 0.02, respectively). There were no statistically significant correlations between muscle volume andjoint angular velocity. These results suggested that hip joint flexor strength ispossibly an important factor to swing up the lead leg quickly during hurdling motion

MEASUREMENT OF FORCES EXERTED DURING SWEEPING IN CURLING

INTRODUCTION: Sweeping is performed to correct the speed or the trajectory of the stone thrown in the game of curling. Curlers are asked to sweep the ice in front of the sliding stone strongly. Therefore we attempted to develop a simple device for measuring the forces exerted on the brush during the sweeping. The present study compared the forces exerted on the brush with the ground reaction forces during the sweeping

THE RELATIONSHIP BETWEEN TRUNK KINEMATIC VARIABLES AND UNDERWATER UNDULATORY SWIMMING PERFORMANCE IN COMPETITIVE SWIMMERS

The purpose of this study was to examine the relationship between selected trunk kinematic variables and undulatory underwater swimming performance in competitive swimmers. Eight male and 2 female swimmers performed 15 m UUS with their maximum efforts. Three-dimensional coordinate of markers attached to bony configurations were corrected during Pearson’s product moment by using the underwater motion capture system. The range of motion and the corresponding angular velocity were computed for lower waist, upper waist and chest. The relationship between horizontal velocity of center of mass and each kinematic variable was then examined. No significant correlations were found between horizontal velocity and each range of motion. The horizontal velocity was significantly correlate with the angular velocity of lower waist and of chest, but not with the corresponding value of upper waist. The current results suggest that the swimmers produce the great horizontal velocity by increase in trunk angular velocities rather than by increase in trunk range of motion

COMPARISON OF GOLF SWING PATTERNS IN SKILLED FEMALE GOLFERS AMONG THREE DIFFERENT CLUBS

The purpose of this study was to compare golf swing patterns using three different clubs among skilled golfers. Five right-handed female professional golfers used their own three clubs (driver, 5-iron, and 9-iron) to hit standard golf balls in our laboratory. 3D coordinates of body and club landmarks during the swing motions were recorded using a 3D motion capture system with operating at 250 Hz frame rates. As the results, the acceleration of club head in each club during downswing reached a maximum around about 0.08 s before impact during similar swing time, and the height of club head at the maximum acceleration showed about 55% of ratio for the body height despite differences of clubs. Skilled golfers therefore might feel as the similar patterns of golf swing even if they are swinging with different length clubs