Direct contact and very rapid valgus distortion characterise the injury mechanism of anterior cruciate ligament ruptures in judo.

PURPOSE: To analyse anterior cruciate ligament (ACL) rupture (ACLR) injury mechanisms in competitive judo using systematic video analysis, focusing on contact situations and biomechanics. METHODS: Seventeen videos of judo competitions wherein athletes developed ACLRs were included and retrospectively evaluated by five analysts. In all videos, the moment of initial contact and the index frame were defined. The judo techniques leading to the injury; the occurrence of direct contact, indirect contact or noncontact mechanisms; the time interval between the initial contact and index frame; the positions of the hip, knee and foot in relation to the initial contact and index frame; and the balance status during the initial contact and index frame were recorded. RESULTS: Eleven (65%) of ACLRs in judo involved direct contact. The mean time interval between initial contact and index frame was 15 ± 22 ms. Thirteen (77%) athletes were not balanced at initial contact. In the index frame, the hip was abducted in all cases and in combination with internal rotation in 12 (71%) cases. From initial contact to index frame, hip flexion increased in all cases; at index frame, the knee joint was internally rotated relative to the trunk in 12 (71%) cases, and the knee flexion angles increased from the initial contact. In the index frame, the foot was externally rotated relative to the knee in 12 (71%) cases, and severe valgus development of the knee with valgus collapse was observed in 14 (82%) cases. CONCLUSIONS: A direct attack on the knee was the most common injury mechanism observed. Valgus distortion appears to be the most important component of the mechanism of injury. With this knowledge, 'modified defence reactions' for specific judo techniques can be developed to reduce the injury risk. LEVEL OF EVIDENCE: Level IV.

Lateral preference in complex combat situations: Prevalence and relationship with general measures of hand and foot preference.

Laterality is considered relevant to performance in combat sports with particular emphasis being placed on fighters' handedness and combat stance. Such approach, however, may fall too short to understand the role of laterality in sports where fighters are allowed to use their hands and feet standing and on the ground. Here, we referred to grappling sports (i) to estimate lateral preferences in selected combat situations and (ii) to test for an association between those preferences and common measures of hand and foot preference. Based on the responses of 135 experienced grapplers who participated in an online questionnaire lateral preference, at the group-level, was revealed in 12 out of 18 combat situations. At an item-level, common measures of lateral preference and grappling-specific lateral preference were related in three out of 36 conditions (footedness only, not handedness). Across items, scores in a grappling-specific laterality index were positively related with foot but not with hand preference scores. Implications for the assessment of lateral preference in combat sports and the use of item-specific terminology in this context are discussed. On a broader scale, we also elaborate on potential consequences of our findings with regard to evolutionary explanations of the maintenance of left-handedness in humans.

Variability Analysis in Judo Para Athletes With Visual Impairments: Match-Outcome Performance in the Tokyo 2020 Paralympic Games With Evidence From the New Classification System.

Match-related performance analysis in judo Para athletes with visual impairments is important to coaches and staff to identify technical-tactical profiles of their athletes and opponents but also to identify whether there are similar characteristics in each visual class. Thus, this study explores the match-related performance in judo Para athletes and verifies the relationship between performance using the old and new classification systems. The match-derived variables were analyzed using different statistical methods considering a total of 182 matches from the Tokyo 2020 Paralympic Games. The results indicated that performance was affected by sex and degree of impairment. The new classification system seems suitable for grouping Para judo athletes, as it differentiates performance between the two proposed classes (J1 and J2), since athletes from each group compete separately. Furthermore, different variability index measures were correlated with competitive performance, demonstrating a specific performance profile for each sport class in judo.

Brain structural correlates of psychopathic traits in elite female combat-sports athletes.

Psychopathy is characterized by glibness and superficial charm, as well as a lack of empathy, guilt and remorse, and is often accompanied by antisocial behaviour. The cerebral bases of this syndrome have been mostly studied in violent subjects or those with a criminal history. However, the antisocial component of psychopathy is not central to its conceptualization, and in fact, psychopathic traits are present in well-adjusted, non-criminal individuals within the general population. Interestingly, certain psychopathy characteristics appear to be particularly pronounced in some groups or professions. Importantly, as these so-called adaptive or successful psychopaths do not show antisocial tendencies or have significant psychiatric comorbidities, they may represent an ideal population to study this trait. Here, we investigated such a group, specifically elite female judo athletes, and compared them with matched non-athletes. Participants completed psychopathy, anger, perspective-taking and empathic concern questionnaires and underwent structural magnetic resonance imaging (MRI). Grey matter volume (GMV) was computed using voxel-based morphometry from the T1-weighted images. Athletes scored significantly higher in primary psychopathy and anger and lower in empathy and perspective taking. They also exhibited smaller GMV in the right temporal pole, left occipital cortex and left amygdala/hippocampus. GMV values for the latter cluster significantly correlated with primary psychopathy scores across both groups. These results confirm and extend previous findings to a little-studied population and provide support for the conceptualization of psychopathy as a dimensional personality trait which not only is not necessarily associated with antisocial behaviour but may potentially have adaptive value.

How wide should you view to fight? Establishing the size of the visual field necessary for grip fighting in judo.

Peripheral vision is often considered vital in (combat) sports, yet most experimental paradigms (e.g., eye tracking) ignore peripheral information or struggle to make inferences about the role of peripheral vision in an in-situ performance environment. This study aimed to determine where visual information is located in the peripheral field during an in-situ combat sports task. Eight advanced judokas competed in grip-fighting exchanges while wearing a mobile eye-tracker to locate gaze direction. Three-dimensional position data of the head and hands were tracked using a VICON motion capture system. Gaze analysis through automatic feature detection showed that participants predominantly fixated on their opponent's chest. Kinematic data were used to calculate the angles between the opponent's hands and the gaze-anchor point on the chest of the opponent. Results revealed a nonlinear relationship between visual field (VF) size and visibility of the hands, with athletes needing a VF of at least 30-40 degrees radius to simultaneously monitor both hands of the opponent most of the time. These findings hold implications for the regulation of Paralympic judo for athletes with vision impairment, suggesting that a less severe degree of impairment should be required to qualify than the current criterion of 20 degrees radius.

Cervical Artery Dissections and Ischemic Strokes Associated with Vascular Neck Compression Techniques (Sportive Chokes).

BACKGROUND: Strangulation as a fight-finishing maneuver in combat sports, termed "choking" in that context, occurs worldwide millions of times yearly. This activity can be trained safely, but devastating injuries can occur. OBJECTIVE: Our aim was to present a case series of cervical artery dissections and ischemic strokes associated with sportive choking. Sharing these cases is meant to draw awareness, to assist emergency physicians in caring for these athletes, and to provide a platform for further research. METHODS: Institutional Review Board approval was obtained. Participants consented for medical information transfer and anonymous academic reproduction. The minimum medical record information necessary for inclusion was a report of diagnosis-confirming advanced imaging. Participants were contacted for primary information in addition to what the medical records could provide and to confirm some information in the record (e.g., pertinent medical history, demographic characteristics, choking event description, medical care, and commentary on their current health). Medical records and additional first-hand information were reviewed and participants were included if they had a diagnosed dissection or stroke likely associated with a sportive choke. RESULTS: Ten cases met all criteria for inclusion. There were 5 cases of carotid artery dissection, 3 cases of vertebral artery dissection, and 2 cases of ischemic stroke without dissection. Nine of 10 participants survived and 3 of 10 have returned to submission grappling training. CONCLUSIONS: Cervical artery dissections and ischemic strokes can occur in association with sportive choking. Emergency physicians must be aware of the widespread nature of this activity and must be vigilant in approaching management of patients with symptoms consistent with these injuries.

Does ipsilateral and bilateral knee strength status predict lower extremity injuries of elite judokas; a prospective cohort study.

The association of pre-participation knee muscle strength status with lower limb injury occurrence was investigated. Knee extensors and flexors muscle strength status including the traditional hamstrings/quadriceps (H/Q), Q/Q, H/H, and the non-dominant H/Q: dominant H/Q, HQ:HQ, ratios were recorded before the 10 month judo activity. Fifteen lower limb sport injuries were recorded for 53 judokas during the follow-up questionnaires. Significant accuracy of dominant H/Q ratio 60º/s (AUC 0.702, 95% CI 0.520 to .883, p = 0.023), as well as HQ:HQ ratios 300º/s (AUC .318, 95% CI 0.138 to 0.497, p = 0.040), and 60 º/s (AUC 0.311, 95% CI 0.130 to 0.491, p = .033) were revealed discriminating between injured and uninjured judokas. The optimum cut-off of dominant H/Q ratio associated with belonging to uninjured judokas group was 43.2% (sensitivity, 0.974; specificity, 0.533). Isokinetic knee muscle dynamometry is useful for predicting the likelihood of lower limb injuries in professional judokas during competitive activity.

Pre-participation testing of ipsilateral and bilateral knee extensors and flexors strength ratios can contribute to an injury prevention program for judokas.Ipsilateral and bilateral strength ratios should be monitored at lower and higher angular isokinetic velocities.

Martial arts training is related to implicit intermanual transfer of visuomotor adaptation.

Recent work identified an explicit and implicit transfer of sensorimotor adaptation with one limb to the other, untrained limb. Here, we pursue the idea that different individual factors contribute differently to the amount of explicit and implicit intermanual transfer. In particular, we tested a group of judo athletes who show enhanced right-hemispheric involvement in motor control and a group of equally trained athletes. After adaptation to a 60° visual rotation, we estimated awareness of the perturbation and transfer to the untrained, non-dominant left hand in two experiments. We measured the total amount of intermanual transfer (explicit plus implicit) by telling the participants to repeat what was learned during adaptation, and the amount of implicit transfer by instructing the participants to refrain from using what was learned and to perform movements as during baseline instead. We found no difference between the total intermanual transfer of judokas and running experts, with mean absolute transfer values of 42.4° and 47.0°. Implicit intermanual transfer was very limited, but larger in judokas than in general sports athletes, with mean values of 5.2° and 1.6°. A multiple linear regression analysis further revealed that total intermanual transfer, which mainly represents the explicit transfer, is related to awareness of the perturbation, while implicit intermanual transfer can be predicted by judo training, amount of total training, speed of adaptation, and handedness scores. The findings suggest that neuronal mechanisms such as hemispheric interactions and functional specialization underlying intermanual transfer of motor learning may be applied according to individual predisposition.

A 10-week judo-based exercise programme improves physical functions such as balance, strength and falling techniques in working age adults.

BACKGROUND: Falls and fall-related injuries are major threats not only for older adults but also for younger age groups such as working-age adults. It has been shown that it is possible to reduce the risk of falls and fall-related injuries, to some extent. However, interventions aiming at reducing both the risk of falls and mitigating fall-related injuries through teaching safe falling techniques are still sparsely investigated. The aim with this study was to investigate the effect of a 10-week workplace-based judo inspired exercise programme (Judo4Balance). The measures in the study include physical functions, fall-related self-efficacy and safe falling techniques. METHODS: A total of 142 working-age adults participated in this non-randomised controlled study. The participants were allocated to the Judo4Balance group (n = 79), or to a waiting list control group (n = 63). The mean age was 47 years (18-68). The recruitment period was from May 2018 to October 2019. A total of 128 participants were included in the analysis. Logistic Regression models were used to analyse the outcomes: physical function, balance and fall-related self-efficacy as well as falling techniques (backwards and forwards). RESULTS: At the 10-week follow-up, the results displayed significant differences between the two groups in all measurements, except for the fall-related self-efficacy with OR = 1.8. Techniques for falling forwards and backwards displayed the highest OR = 124.1 and OR = 98.9. Physical function and balance showed OR = 3.3 and OR = 6.4. CONCLUSIONS: This exercise programme under study displayed significant differences in strength, balance and safe falling techniques between the groups. It is suggested that these functions, which were studied here, can effectively be trained in working-age adults by using the Judo4Balace exercise programme. Thus, it may be beneficial to further investigate and include training in proper falling techniques when designing fall prevention exercise programmes. Furthermore, it may be a novel way of addressing fall-related injuries, which are of utmost importance to prevent in near future. TRIAL REGISTRATION: NCT04294342 . Registered 4 March 2020 - The Impact of Specifically Adapted Judo-based Training Program on Risk Factors for Falls Among Adults - Full Text View - ClinicalTrials.gov.

Injury incidence, severity and profile in Olympic combat sports: a comparative analysis of 7712 athlete exposures from three consecutive Olympic Games.

OBJECTIVES: To describe and compare the epidemiology of competition injuries in unarmed combat sports (ie, boxing, judo, taekwondo and wrestling) in three consecutive Olympic Games. METHODS: Prospective cohort study using injury data from the IOC injury surveillance system and exposure data from official tournament records at three consecutive Olympic Games (ie, Beijing 2008, London 2012 and Rio de Janeiro 2016). Competition injury incidence rates per 1000 min of exposure (IIRME) were calculated with 95% CIs using standard formulae for Poisson rates. RESULTS: The overall IIRME was 7.8 (95% CI 7.0 to 8.7). The IIRME in judo (9.6 (95% CI 7.8 to 11.7)), boxing (9.2 (95% CI 7.6 to 10.9)) and taekwondo (7.7 (95% CI 5.6 to 10.5)) were significantly higher than in wrestling (4.8 (95% CI 3.6 to 6.2)). The proportion of injuries resulting in >7 days absence from competition or training was higher in wrestling (39.6%), judo (35.9%) and taekwondo (32.5%) than in boxing (21.0%). There was no difference in injury risk by sex, weight category or tournament round, but athletes that lost had significantly higher IIRME compared with their winning opponents (rate ratio 3.59 (95% CI 2.68 to 4.79)). CONCLUSION: Olympic combat sport athletes sustained, on average, one injury every 2.1 hours of competition. The risk of injury was significantly higher in boxing, judo and taekwondo than in wrestling. About 30% of injuries sustained during competition resulted in >7 days absence from competition or training. There is a need for identifying modifiable risk factors for injury in Olympic combat sports, which in turn can be targeted by injury prevention initiatives to reduce the burden of injury among combat sport athletes.

Effect of vision impairment on match-related performance and technical variation in attacking moves in Paralympic judo.

In Paralympic judo for athletes with vision impairment (VI judo) all eligible athletes (i.e. B1, B2 and B3 classes) compete against each other in the same competition. Evidence suggests that athletes with more impairment may be disadvantaged, but that more sensitive measures of performance are necessary to understand the impact of impairment on performance. The aim of this study was to investigate the relationship between Para sport class and technical variation, time-motion variables, and performance in Paralympic judo. All 175 judo matches from the Rio 2016 Paralympic Games were analysed across 129 competitors (82 male and 47 female). The main results indicated that athletes who demonstrated less technical variation also experienced less competitive success, with the functionally blind athletes (class B1) demonstrating less technical variation than partially sighted (class B2 and B3) athletes (p < 0.05). There was no difference in the time-motion variables between sport classes (p > 0.05). We conclude that measures of technical variation are sensitive to differences in impairment and are suitable for studies that investigate the impairment-performance relationship in VI judo. Results further confirm that some athletes with impairment are disadvantaged under the current rules of VI judo.

May the best-sighted win? The relationship between visual function and performance in Para judo.

This study aimed to establish the optimal cut-off point(s) between classes in a new, evidence-based classification system for VI judo. We collected results from international VI judo competitions held between 2012 and 2018. Data on visual acuity (VA) and visual field (VF) measured during classification were obtained. Performance was determined by calculating a win ratio for each athlete. VA was significantly associated with judo performance (r = -.33, p <.001), VF was not (r =.30, p =.15). Decision tree analysis suggested to split the data into two groups with a VA cut-off of 2.5 logMAR units. Stability assessment using bootstrap sampling suggested a split into two groups, but showed considerable variability in the cut-off point between 2.0 and 3.5 logMAR. We conclude that to minimise the impact of impairment on the outcome of competition, VI judo should be split into two sport classes to separate partially sighted from functionally blind athletes. To establish an exact cut-off point and to decide if other measures of visual function need to be included, we argue for continued research efforts together with careful evaluation of research results from a multidisciplinary perspective.

Statistical Extraction Method for Revealing Key Factors from Posture before Initiating Successful Throwing Technique in Judo.

Many methods such as biomechanics and coaching have been proposed to help people learn a certain movement. There have been proposals for methods to discover characteristics of movement based on information obtained from videos and sensors. Especially in sports, it is expected that these methods can provide hints to improve movement skills. However, conventional methods focus on individual movements, and do not consider cases where external factors influence the movement, such as combat sports. In this paper, we propose a novel method called the Extraction for Successful Movement method (XSM method). Applying the method, this paper focuses on throwing techniques in judo to discover key factors that induce successful throwing from the postures right before initiating the throwing techniques. We define candidate factors by observing the video scenes where the throwing techniques are successfully performed. The method demonstrates the significance of the key factors according to the predominance of factors by χ2 test and residual analysis. Applying the XSM method to the dataset obtained from the videos of the Judo World Championships, we demonstrate the validity of the method with discussing the key factors related to the successful throwing techniques.

Weight Loss Strategies in Male Competitors of Combat Sport Disciplines.

Background and objective: The use of suboptimal weight loss strategies in order to reach specific weight ranges as observed in combat sport disciplines can give rise to severe health problems. However, particular aspects regarding management of weight category comparing three sport disciplines remain to be investigated. Therefore, the aim of the present study was to obtain information regarding the weight loss strategies that competitors performed before a tournament. Materials and Methods: This article describes the most common dietary-nutritional strategies used by 140 national university male competitors of judo (n = 52), karate (n = 40) and taekwondo (n = 48) in order to achieve a specific weight, according to the rapid weight loss questionnaire (RWLQ) and the EAT-27 questionnaire. Results: Around 50% of participants were not involved in a weight loss process. Among the remaining participants, we considered three periods for weight reduction: less than 1 week (35% in judo, 8% in karate and 19% in taekwondo), less than 1 month (17% in judo, 15% in karate and 26% in taekwondo) and more than 1 month (0% in judo, 5% in karate and 21% in taekwondo). Severe fasting, focused on food/water restriction, was the most commonly used strategy, being more frequent in judo players. Light weight judo practitioners generally lost 2-5 kg before the contest. One third of participants avoided carbohydrate consumption when performing food restriction. Finally, individuals that reduced weight in the last week seemed to develop an unhealthy psychological relationship with food. Conclusion: All these aspects could be particularly relevant, providing information regarding how competitors manage basic nutritional concepts that guide dieting strategies. This information is relevant to prepare future educational interventions in the area of nutrition for competitors, coaches and technical staff.

The prevalence of orofacial injuries in judo: A cross-sectional study.

BACKGROUND/AIMS: Judo is a popular martial art with a high risk of injury. Notwithstanding this risk, mouthguards were not allowed until June 2018. The aim of this study was to measure the prevalence of traumatic injuries in judo with a particular focus on dental and lip injuries. A further aim was to assess the influences of increased overjet and wearing fixed orthodontic appliances. MATERIAL AND METHODS: Judokas (n = 382) from two judo clubs in Bern, Switzerland, were interviewed with a standardized questionnaire. RESULTS: About two thirds had suffered at least one traumatic injury with a high number of limb injuries (n = 1054), followed by face injuries (n = 855) and spine, torso, occiput or neck injuries (n = 84). Among the face injuries, 562 lip injuries were recorded. A significantly higher number of lip injuries were found for judokas who wore fixed orthodontic appliances compared to judokas who never wore such appliances. Forty-seven dental trauma incidents during judo were recorded. During both judo and leisure time, 161 dental trauma incidents were recorded. Individuals with lip incompetence and increased overjet showed the highest number of dental injuries ( x ¯ = 0.815; SD = 0.622), which differed in statistically significant ways from the number of dental injuries in individuals with lip incompetence and normal or reduced overjet ( x ¯ = 0.278; SD = 0.461). For individuals with no lip incompetence, no difference between the sub-group with an increased overjet and the sub-group with a normal or reduced overjet could be found. Nobody in the study population was wearing a mouthguard, and the acceptance of mouthguards was low (9.7%). CONCLUSION: It is important to increase the awareness of the recent authorization of mouthguards and to promote their acceptance among judokas. The combination of increased overjet and lip incompetence was more relevant for the dental trauma risk than an increased overjet alone.

Lifetime use of complementary and alternative medicine therapies among community-dwelling older people in Japan.

[Purpose] Three complementary and alternative medicine (CAM) therapies: "Judo therapy", "acupuncture and moxibustion", and "Japanese traditional massage and finger pressure" have been partially covered by the national health insurance in Japan. The lifetime prevalence of the use of these CAM therapies is not well known. The aim of the present study was to report the prevalence of the lifetime use of these CAM therapies. [Participants and Methods] We conducted a mailed self-administered questionnaire survey among community-dwelling older people in Japan in 2015. They were asked whether they had undergone any treatments with the 3 CAM therapies. The answers obtained were classified into 3 categories: current, ever, or never. We defined lifetime prevalence as the proportion of individuals who are currently using or have ever used any of these 3 therapies in the population. [Results] Overall, we approached 1051 individuals and 983 agreed to participate. Lifetime prevalence of Judo therapy, acupuncture and moxibustion, and Japanese traditional massage and finger pressure use was 28.0%, 17.8% and 15.8%, respectively, among males, and 44.5%, 18.4%, and 27.3%, respectively, among females. [Conclusion] These results showed that not only Western medicine but also CAM therapies are common among older people in Japan.

Cauliflower ear among Finnish high-level male wrestlers and judokas is prevalent and symptomatic deformity.

Our research aimed to study the prevalence, concerns, and treatment practices related to cauliflower ear among Finnish wrestlers and judokas. In total, 32 Finnish wrestlers and 31 judokas completed a questionnaire at training sessions or at a competition. All participants were adults competing at the national or international levels. We also took lateral digital photographs of participants' ears. A senior author graded the overall appearance of the auricles on a scale from 0 to 5 (0 = normal auricle, 5 = extreme cauliflower ear). Cauliflower ear was more prevalent among male athletes (84%, 46/55) than female athletes (0%, 0/8, P < .001). Almost all (96%) had sought treatment for an auricular hematoma. The most prevalent treatment modality was needle aspiration (96%). Most (76%) had received treatment from individuals not representing the healthcare profession. Only one athlete reported receiving successful treatment. No complications from treatment were reported. Almost all participants (96%) reported some symptom from the cauliflower ear, typically pain. None regretted their cauliflower ear(s), and 41% of athletes with cauliflower ear considered it desirable. Cauliflower ear is a common and symptomatic deformity among high-level Finnish wrestlers and judokas. Despite the symptoms, it is accepted and sometimes even desired among the athletes.

An expert's mind in action: Assessing attentional focus, workload and performance in a dynamic, naturalistic environment.

The aims of this study were to (1) to explore attentional strategies in expert judo players and (2) investigate how attentional focus affects performance effectiveness and perceptions of workload in expert judo players during real competitions. Fourteen expert male judo players participated in the study. A simulated recall method was used following participants' competition to explore contents of attention qualitatively. The data analysis process for the qualitative portion of the study was an iterative process between inductive and deductive analyses. Quantitative analyses of performance outcomes and workload were then associated with the qualitative findings. Qualitative results revealed that the focus of attention was dynamic and complex, with technical aspects of the movements as the highest identified focus. Quantitative analyses revealed that reporting a lower quantity of attentional cues and higher percentage of focus on opponent resulted in higher performance effectiveness and less perceptions of workload. This study indicates that cognitive control and automaticity may work in a synergistic manner for successful skill execution in expert performance.

Both Unopposed and Opposed Judo Tasks are Suitable for Analyzing Changes in Lateral Preference.

Judo coaches aim to develop left-handed techniques in right-handed judoka due to a potential frequency-dependent strategic advantage during competition. Thus, easily completed tasks are needed to track the progression of the lateral preference index (percentage as right-handed actions). Thirty naïve volunteers performed two tasks, an unopposed repetition-based dynamic task (yakusoku geiko) and an opposed-bouts task (randori), before and after eight-week training protocols differing in the executing side. Training protocols consisted of a control group (without any instruction regarding the practice side), a bilateral group (practicing with both dominant and nondominant sides), and a nondominant group (practicing exclusively on the nondominant side). ANOVA-type tests were used for analyzing the suitability of the unopposed repetition-based dynamic task for detecting changes in the lateral preference index and for analyzing the concordance between tasks. Additionally, concordance was tested with Spearman's rank correlations and Bland-Altman plots. Lower lateral preference indices (i.e., reductions of executions as right-hander) were observed after training in the nondominant group and in comparison with the control group and bilateral group on the posttest (p < 0.05). ANOVA-test for concordance analysis revealed no differences between tasks (p > 0.05) with significant correlations (p < .05) and low bias during the pretest (ρ = 0.563; bias: 4.29, 95% LoA: -36.32-27.74%) and the posttest (ρ = 0.718, bias: 0.69, 95% LoA: -39.37-40.77%). In conclusion, an unopposed repetition-based dynamic task detected reductions in lateral preference index after an eight-week nondominant training period. These results agreed with those observed with the opposed-bouts task. This indicates the eligibility of yakusoku geiko for coaching delivery due to general suitability of the unopposed repetition-based dynamic task to track the maintenance or progression of left-handedness in judo trainees.

Judo Practice in Early Age Promotes High Level of Bone Mass Acquisition of Growing Boys' Skeleton.

The current study aimed to exhibit effects of judo training for at least 2 yr on bone mass parameters in growing boys. Our population was composed of one hundred and thirty boys in tanner stage 1 and aged 10.52 ± 0.86 yr. Eleven judo players were therefore, excluded from the study because they do not have participate regularly to the judo training sessions during the last 2 yr. The resting sample was divided into two groups: 50 judo players (JU group) and 69 controls (C group). Bone mineral density (BMD), bone mineral content (BMC), and bone area (BA) were evaluated by using dual-photon X-ray absorptiometry on weight-bearing sites: the whole body, lumbar spine (L2-L4), legs, femoral necks and hips and on the non-weight bearing sites: arms and radiuses. Our findings displayed that judo participation was markedly associated with greater values of bone mass parameters in young judo players than control group. Accordingly, the BMD and BA results exhibited significant differences in the whole body, legs, dominant total hip, arms and both whole radiuses in addition to the dominant femoral neck, the non-dominant total hip and except the non-dominant whole radius for the BMC parameter. Additionally, data of the subject within t test has shown significant differences of bone mass parameters only in the non weight-bearing sites in the judo players without any obvious variation in the controls. Differences of BMD observed on the dominant arm and whole radius in addition to the increased BMC values showed in the dominant whole radius compared with their contra-lateral sites in judo players without any marked variation of BA parameters in all sites in both groups. In growing boys, judo practice was obviously associated with osteogenic effects in specific sites.