EFFECTS OF STRETCH-SHORTENING CYCLE DURING TRUNK-TWIST EXERCISE USING DIFFERENT LOADS

The purpose of this study was to investigate the effects of stretch-shortening cyde (SSC) movement during bunk-twist and whether the effects change on increasing the loads by using a special trunk-twist machine. Twenty-one male college students performed trunktwist exercise with 3 loads. Participants performed this exercise for each load by using SSC and not using SSC (CON). Kinematic and kinetic data were recorded using Vimn system (250 Hz) and force platform (1,000 Hz). The following effects of SSC for this exercise were observed: (1) peak bar angular velocity was not potentiated by SSC, but SSC contributed to the acceleration of bar angular velocity and (2)for heavy loads, SSC did not affect mean angular velocity of the bar, upper trunk and pelvic rotation. Moreover, peak joint torque power of trunk-twist significantly decreased with heavy loads

Copper-Catalyzed Regioselective C-H Amination of Phenol Derivatives with Assistance of Phenanthroline-Based Bidentate Auxiliary

A copper-catalyzed regioselective direct amination of phenol derivatives with diarylamines via phenanthroline-based bidentate auxiliary-directed C-H cleavage has been developed. This reaction proceeds smoothly with only a copper salt and air as a terminal oxidant to produce the corresponding o-aminophenols in good yields. Moreover, the directing group can be easily attached, detached, and recycled. Additionally, preliminary computational studies of the reaction with DFT have also been performed.Takamatsu K., Hayashi Y., Kawauchi S., et al. Copper-Catalyzed Regioselective C-H Amination of Phenol Derivatives with Assistance of Phenanthroline-Based Bidentate Auxiliary. ACS Catalysis. 9(6), 5336-5344 (2019), 7 June 2019; © 2019 American Chemical Society. https://doi.org/10.1021/acscatal.9b01145

Copper-Mediated Decarboxylative C–H Arylation of Phenol Derivatives with ortho-Nitrobenzoic Acids Using Phenanthroline-Based Bidentate Auxiliary

A copper-mediated decarboxylative C–H arylation of phenol derivatives with ortho-nitrobenzoic acid salts via phenanthroline-directed C–H cleavage has been developed. The N,N-bidentate phenanthroline auxiliary uniquely promotes the reaction only in the presence of a copper salt to produce the corresponding biaryls in acceptable yields. Moreover, the directing group can be easily introduced and removed. Additionally, preliminary computational mechanistic studies with DFT have also been performed.Takamatsu K., Hayashi Y., Kawauchi S., et al. Copper-Mediated Decarboxylative C–H Arylation of Phenol Derivatives with ortho-Nitrobenzoic Acids Using Phenanthroline-Based Bidentate Auxiliary. ChemistrySelect 4, 11833 (2019); https://doi.org/10.1002/slct.201902860

COMPARISON OF PULL AND CATCH PHASES DURING CLEAN EXERCISESE

The purpose of this study was to identify differences in kinetic characteristics between the performed the PC at 30%, 60%, and 90% of one repetition maximum. Kinetic data were collected from recorded data by using a Vicon motion system and force platforms. In the comparison between the pull and catch phases, the kinetic characteristics of the catch phase were as follows: 1) The peak ground reaction force did not significantly differ according to load. 2) Ankle and knee kinetics showed large values. 3) The force and power in the ankle and knee did not significantly differ between the light load (30%) and heavy load (90%). Therefore, the importance of using PC in training not only for the pull movement but also for the catch movement

THE EFFECT OF INCREASING JUMP STEPS ON THE TAKE-OFF LEG IN BOUNDING

The purpose of this study was to clarify the effect of increasing jump steps in bounding in terms of three-dimensional joint kinetics for the take-off leg. Eleven male track and field athletes performed horizontal bounding from the standing posture. Kinematic and kinetic data were recorded using a Vicon T20 system (250 Hz) and force platforms (1,000 Hz). As jump steps increased, the joint kinetics characteristics are as follows: 1) ankle plantar flexion torque and knee extension torque and power increased, but hip extension torque and power did not increase; and 2) hip external torque and power (negative and positive) increased, particularly hip abduction torque and power. Therefore, in bounding initiated from the standing posture, ankle and knee joint kinetics from the sagittal plane and 3dimensional hip joint kinetics increased, particularly on hip adduction-abduction axis

DEVELOPMENT OF MULTISTEP DROP JUMP TEST BY USING DIFFERENT DROP HEIGHTS

We used different drop heights to evaluate the drop jump (DJ) test in elite athletes. Male jumpers (n=10) performed the test at 0.3, 0.6, 0.9, and 1.2 m. Jumping motions in the sagittal plane and the ground reaction force were recorded using a high-speed camera and force platform, respectively. The amount of negative work by 3 lower extremity joints increased with increased drop height of the DJ test, mainly at the hip joint. There were different performance patterns on the DJ test and lower extremity power output with an increased drop height according to individual characteristics of elite jumpers, compared with the average pattern. Jump performance was correlated with the DJ index at DJ1.2 and the decreased rate of the index from DJ0.3 to DJ1.2. Thus, to evaluate elite jumpers’ performance, various height ranges including a higher drop height should be used

DEVELOPMENT OF A NEW ASSESSMENT METHOD FOR THE REBOUND JUMP TEST

We have proposed a new assessment method using joint kinetics and performance variables in the rebound jump (RJ) test. Twenty-seven male jumpers performed the RJ test. The Quick Motion Analysis System (jointly developed with DKH Inc.) was used to measure joint torque, power, and work of the three lower limb joints in real time, with high precision. High-performance jumpers had high performance values and showed a significantly large amount of joint work in the ankle and hip joints on the RJ test. Comparison of the work of the three lower limb joints confirmed a conflicting relationship between the hip and knee joints and that of the ankles, indicating that this new system is useful for evaluating joint kinetics of the three lower limb joints and may contribute greatly to the assessment of muscle strength and power

THE CHARACTERISTICS OF HITTING MOTION USING BATS HAVING DIFFERENT LENGTH AND MASS BUT EQUAL MOMENT OF INERTIA

The aim of this study was to investigate the characteristics of hitting motion when using training bats with altered length and mass. Four different long bats (LB) and four different weight bats (WB) that had the equal moment of inertia (MOI) were manufactured based on a normal bat (NB; 0.84 m, 0.90 kg). Eleven male collegiate baseball players performed tee batting with maximal effort. The hitting motion was analyzed using a VICON (250 Hz) to collect nine reflective markers fixed on the body and bat. Results indicated that the angular displacement of the trunk twist tended to be larger in LB with increasing MOI. And it was remarkable in subjects with smaller angular displacement of trunk twist in NB. Thus, compared to WB, LB may contribute to a larger angular displacement of trunk twist, particularly in players with smaller angular displacement of trunk twist in NB

Generator sources of 14Hz/12Hz sleep spindles during stage 2 sleep

The present study investigated the equivalent dipole sources of two types of human sleep spindles (14 and 12Hz) during stage 2 sleep. Dipole analysis of the 21 scalp EEGs (Fp1,Fp2,F3,F4,C3,C4,P3,P4,O1,O2,F7,F8,T3,T4,T5,T6,Fpz, Fz, Cz, Pz and Oz) was carried out on ten male subjects (20-26yr). This study showed that sleep spindle can be represented by single equivalent dipole. For both 14 and 12Hz sleep spindles, the equivalent dipole sources appeared in center of the brain. The orientation of the equivalent dipole of 14Hz sleep spindle was in the centro-parietal direction, while that of 12Hz sleep spindle was in the frontal direction. These results suggest that both types of sleep spindle activities are generated in the thalamus, and the thalamo-cortical pathway are different for the two types of sleep spindles