EFFECT OF LEG STIFFNESS DURING REBOUND JUMP ON SPRINT RUNNING KINEMATICS AND KINETICS

We investigated the relationship between stiffness in rebound jump (RJ) and kinematics and kinetics of the support- and swing-leg in sprint running (SP). We included 13 male track and field athletes performing maximal effort SP and RJ. During the support phase, kinematics, kinetic, and leg stiffness parameters were calculated using a force platform and data from a high-speed video camera that recorded movement in the sagittal plane. A significant correlation was observed between SP and RJ for stiffness (r = 0.683). In SP, stiffness was significantly correlated with contact time (r = -0.659), mean joint torque at the ankle (r = 0.703) and knee (r = -0.726) joints, CG (center of gravity) -toe distance (r = -0.818), and the swing-leg angle (r = -0.676) at touch down. Based on our results, kinematics and kinetics correlated with stiffness in SP are affected by RJ stiffness

Biofilm formation among methicillin-resistant Staphylococcus aureus isolates from patients with urinary tract infection.

Staphylococci have been confirmed to form biofilms on various biomaterials. The purpose of this study was to investigate biofilm formation among methicillin-resistant Staphylococcus aureus (MRSA) isolates from patients with urinary tract infection (UTI) and to assess the relationship between biofilm-forming capacities and virulence determinants/clinical background. Over a 12-year period from 1990 through 2001, a total of 109 MRSA isolates were collected from patients (one isolate per patient) with UTI at the urology ward of Okayama University Hospital. We used the in vitro microtiter plate assay to quantify biofilm formation. We then investigated the presence of several virulence determinants by polymerase chain reaction assay and found eight determinants (tst, sec, hla, hlb, fnbA, clfA, icaA, and agrII) to be predominant among these isolates. Enhanced biofilm formation was confirmed in hla-, hlb-, and fnbA-positive MRSA isolates, both individually and in combination. Upon review of the associated medical records, we concluded that the biofilm-forming capacities of MRSA isolates from catheter-related cases were significantly greater than those from catheter-unrelated cases. The percentage of hla-, hlb-, and fnbA-positive isolates was higher among MRSA isolates from catheter-related cases than those from catheter-unrelated cases. Our studies suggest that MRSA colonization and infection of the urinary tract may be promoted by hla, hlb, and fnbA gene products.</p

THE DIFFERENCES BETWEEN HORIZONTAL AND VERTICAL DIRECTION DURING A SINGLE-LEG REBOUND JUMP: OBTAINED USING THREE-DIMENSIONAL MOTION ANALYSIS

The purpose of this study was to clarify the differences between single-leg rebound jump for horizontal direction (HSJ) and vertical direction (VSJ) in terms of three-dimensional joint kinetics for the take-off leg focused on frontal plane movement. Eleven male track and field athletes were performed the HSJ and VSJ. Kinematics and kinetics data were recorded using Vicon T20 system (250 Hz) and force platforms (1000 Hz). In HSJ, as compared to VSJ, the joint kinetics characteristics are as follows: 1) the hip abduction torque and torque power around the adduction-abduction axis are larger; and 2) the trunk lateral flexion torque and torque power around the adduction-abduction axis are larger. Therefore, the hip adduction-abduction and trunk lateral flexion-extension movement plays an important role in a single-leg jump. Additionally, this is pronounced in HSJ as compared to VSJ

On types for unramified p-adic unitary groups

Folloing the methods of Bushnell-Kutzko for general linear groups, we construct simple types attached to certain skew simple strata for a symplectic group and an unramified unitary group over a non-archimedean local field.Comment: 38pages,no figure

THE DIFFERENCES BETWEEN DOUBLE AND SINGLE LEG TAKEOFF ON JOINT KINETICS DURING REBOUND-TYPE JUMP

The purpose of this study was to identify the differences between double and single leg takeoff on joint kinetics during a rebound-type jump. Twelve male track and field athletes performed repeated rebound-type jumps with double legs (DRJ) and a single leg (SRJ). Kinematics and kinetics data were recorded using a high-speed video camera (300 Hz) and force platforms (1000 Hz). The negative and the positive values of the joint torque power about the ankle joint were significantly lower in DRJ than in SRJ. However, the mean joint extension torque, and the negative value of the joint torque power about the hip joint was larger in SRJ than in DRJ. It is suggested that the joint kinetics characteristics, in SRJ as compared to DRJ, reveals a relatively large joint torque and torque power about the hip joint

THE COMPARISON TO THE CHARACTERISTICS OF THREE-DIMENSIONAL JOINT KINETICS BETWEEN SINGLE LEG AND DOUBLE LEG REBOUND JUMP

The purpose of this study was to clarify the differences between the SRJ and DRJ in terms of three-dimensional joint kinetics for the takeoff leg. Twenty male track and field athletes were performed repeated rebound jump with single leg (SRJ) and double leg (DRJ). Kinematics and kinetics data were recorded using Vicon T20 system (250 Hz) and force platforms (1000 Hz). When comparing a SRJ to a DRJ, the characteristics of the former are as follows: 1) the jump height by a single leg is significantly higher because of the larger hip joint work around the extension-flexion, especially on the abduction-adduction axes; 2) the hip extension and abduction torque is larger; and 3) in the SRJ, the hip abduction torque is larger than the hip extension torque. Therefore, the joint kinetics of the SRJ is characterized by the large hip abduction torque, in addition to the large hip extension torque

SPRINT STEP-TYPE SPECIFIC CHARACTERISTICS OF ANTHROPOMETRIC AND KINEMATIC VARIABLES IN SPRINTING ACCELERATION

The purpose of this study was to compare the anthropometric and the kinematic characteristics during the acceleration phase between stride frequency (SF)-type and stride length (SL)-type sprinters. Seventeen sprinters participated in this study. The maximal 60-m sprints and anthropometric measures were obtained from subjects. Two sprints were recorded by using high-speed cameras. Sprint velocity, SL, SF and their underlying kinematic variables were calculated. Cluster analysis was used to classify the subjects into the SF or SL -type groups (step-type) as indicated by the ratio of the SF and SL at maximum velocity. The SF-type group showed shorter lower limbs length, flight time, lower the height of center of mass at takeoff, smaller swing motion and faster forward rotation of the shank and foot segments than the SL-type group. This study showed the noticeable differences between SFtype and SL-type sprinters were not only in swing motion but also in push-off motion

サンショク ケイコウ ヒョウジホウ ニ ヨル ワニ ノ ハ ト ガッコツ ノ ハツイク ニ カンスル ケンキュウ

大阪大學齒學雜誌 14(2), 17-37, 1969-1