NECK AND TRUNK KINEMATICS AND ELECTROMYOGRAPHIC ACTIVITY DURING JUDO BACKWARD BREAKFALLS

The purpose of this study was to demonstrate the neck and trunk angle time curves as well as electromyographic (EMG) activities during a judo backward breakfall in both experienced and novice judokas. Six experienced and four novice judokas volunteered to participate in the study. Three-dimensional kinematic and EMG data were collected while participants performed five sets of backward breakfalls at their own speed. We demonstrated neck/trunk angle time curves and muscle activation profiles during judo breakfalls. The results showed that there were no significant differences in the variables between experienced and novice judokas, which suggests that even short-term judo practice improves backward breakfall skills and may help prevent injury

KINEMATICS OF FOOT-SHANK COMPLEX IN “KENDO” AND ITS RELATIONSHIP WITH FOOT ARCH HEIGHT

The purpose of this study was to demonstrate 1）the joint couple of foot-shank complex in the kendo motion and 2）the relationship between the kinematic values and the foot arch height. Seventeen experienced kendo athletes volunteered to participate in the study. We instructed the participants to perform three sets of kendo strike-thrust motion with the distance of 2.2m to the target. We obtained joint kinematic data of the foot eversion-inversion and shank rotation angles to the foot during the single support phase of the kendo motion. Our result demonstrated that the foot inversion and shank external rotation movements occur during the single stance phase in experienced kendo athletes in good health. In addition, the foot arch height –length ratio was significantly related to the total range of shank rotation to the foot

EFFECT OF FATIGUE ON ELECTOR SPINAE MUSCLES ON TRUNK POSTURAL KINEMATICS AND ELECTROMYOGRAPHYIC ACTIVITIS DURING REPETITIVE BACK SQUAT

The aim of the present study was to demonstrate the change of the trunk posture and electromyographic (EMG) activities of elector spinae muscle and lower extremity muscles during repetitive squat motion in two different conditions with or without the back muscle fatigue task. The results demonstrated that forward trunk inclination was significantly increased during the no-fatigue condition. In addition, the forward trunk inclination appeared to be greater in the pre-fatigue condition than the non-fatigue condition. In addition, the EMG activities in the erector spinae muscles were significantly increased in the non-fatigue condition, but not in the EMG activities in the pre-fatigue condition. Appropriate muscle strength must be necessary for squat exercise to maximize the training effects and to avoid lower back injuries

KINEMATICS OF JUDO BREAKFALL FOR OSOTO-GARI

The purpose of this study was to identify kinematic parameters of breakfall for osoto-gari that can be distinguished between the experienced and the novice judokas. Eight experienced and four novice judukas volunteered to participate in the study. The motion data of the breakfall for osoto-gari were collected with a three-dimensional motion analysis technique. Our result demonstrated that there are significant differences in the hip movement pattern between the experienced and the novice judokas (

COMPARISON OF KINETICS AND KINEMATICS IN SEOI-NAGE BETWEEN JUDO ATHLETES WITH DIFFERENT SKILL LEVELS

The purpose of the present study was to compare the biomechanics parameters of seoi-nage between a skilled group and an unskilled group. The motion data of the seoi-nage were collected on three male elite judo athletes and sixteen male student judo athletes using a three-dimensional motion analysis technique and groups based on skill level were compared. This study found that the anterior-posterior component of the centre of mass velocity of the tori and average anterior-posterior component of the hip velocity of the swing leg in the knee extension phase were significantly larger in the skilled group than those in the unskilled group. The information suggests that it may be more important for judo athletes to maintain the linear velocity towards an opponent than body position of the tori relative to the uke for better seoi-nage performance

COMPARISON OF SEOI-NAGE TECHNIQUE FOR JUDO ATHLETES OF DIFFERENT SKILL LEVELS

The purpose of the present study was to compare the biomechanics parameters of seoi-nage in judo between highly skilled judo athletes and skilled ones. The motion data of the seoi-nage were collected on three male elite judo athletes and sixteen male student judo athletes using a three-dimensional motion analysis technique. This study found that the anterior-posterior component of the ankle and hip peak velocity of the tori in turning phase were significantly larger in the highly skilled group than the skilled group. In addition, the peak velocities of the ankle and hip were significantly correlated to the peak angular momentum of the tori. The results suggested that it would be useful for judo coaches to pay a greater attention to linear velocity of the lower extremities to evaluate the seoi-nage skill than the knee extension

TRUNK BIOMECHANICS DURING BREAKFALL FOR OSOTO-GARI AND ITS ASSOCIATION WITH JUDO-RELATED HEAD INJURY RISK IN NOVICE JUDOKAS

The incidence of head injuries in novice judo practitioners is of increasing public concern in Japan. This study investigated the correlation between trunk biomechanics and judo-related head injury risk in novice judokas with the aim of developing effective injury prevention strategies. Thirty-one novice judokas were volunteered to participate the study. Three-dimensional motion analysis of the osoto-gari breakfall was performed. A multiple regression analysis was usedto test the correlation between trunk biomechanics and possible head injury risk. We found a significant correlation between the trunk COM velocity and the peak neck angular momentum (F= 13.29, df= 3, P\u3c 0.001, r= 0.77). The result suggests that controlling the trunk COM angular velocity may play an important role in judo-related head injury prevention for novice judokas

KINEMATIC COMPARISON OF THE SEOI-NAGE TECHNIQUE BETWEEN ELITE AND COLLEGE JUDO ATHLETES

The purposes of the present study were to compare the biomechanics parameters of seoi-nage between elite and college judo athletes and to produce the standard motion models of elite and college judo athletes. The motion data of the seoi-nage were collected on three male elite judo athletes and nine male student judo athletes using a three-dimensional motion analysis technique and compared. The results demonstrated that the elite judo athletes flexed the knee of the pivot leg and showed less shoulder rotation angle during the latter half of seoi-nage than the college judo athletes. The present study also revealed that the standard motion model seemed to be valid to represent the characteristics of groups’ motions

BIOMECHANICS OF JUDO BREAKFALL FOR OSOTO-GARI IN ADOLSECENT JUDOKAS

Regardless of relatively higher head injury occurrence, few studies have investigated the biomechanics of a judo breakfall technique in adolescent judokas. The aim of the present study was to demonstrate biomechanical characteristics of the breakfall technique performed by experienced adolescent judokas during the “osoto-gari” throw by comparing it with those performed by experienced adult and novice adult judokas. Motion data from the breakfall technique were collected with a three-dimensional motion analysis method. No significant differences were observed in the hip and neck movement patterns between the novice and the adolescent judokas (p > 0.05), but not between the experienced adult and adolescent judokas. This suggests that regardless of experience, the breakfall skill level of the adolescent judokas is not similar to that of adult experienced judokas

CONTRIBUTION OF MAXIMAL STRENGTH TO PEAK POWER AND RATE OF POWER DEVELOPMENT IN BENCH PRESS MOVEMENT USING FREE WEIGHTS

The purpose of the study was to demonstrate the relationships between peak power output, rate of power development (RPD) and maximal strength in the bench press movement with free weights. Eighteen healthy male subjects volunteered to participate in the study (mean age 21.1±1.4year, standing height 169.9±6.5cm, body mass (BM) 75.6±16.8kg). All subjects had moderate to extensive resistance training experience ranging from 1 to 5 years. The bench press movement was performed with a weight of 50% of one repetition maximum (1RM). Acceleration data were obtained with a uniaxial micromachined accelerometer attached to the centre of a barbell shaft. Based on the acceleration data, peak power output (W), time to peak power (TPP, s) and RPD (W/s) were computed. Significant correlations were found between peak power per body mass vs. 1RM/BM (r = 0.650, ) and RPD/BM vs. 1RM/BM (r = 0.557,. However, RPD/BM and TPP were not significantly different between the high-strength group and the low-strength group. The current findings indicate that increasing maximal strength may play a great role in the peak power improvement, but not on the RPD using free weights. Authors recommend mixed training strategy using a heavy weight and a light to medium weight to effectively improve the bench press performance