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.

Rapid Weight Gain Following Weight Cutting in Male and Female Professional Mixed Martial Artists.

Rapid weight loss or "weight cutting" is a common but potentially harmful practice used in mixed martial arts competition. Following the official weigh-in, competitors refeed and rehydrate themselves in a process known as rapid weight gain (RWG) to realize a potential competitive advantage. While data from surveys and small series have indicated the majority of mixed martial arts athletes engage in rapid weight loss, there is a lack of officially collected data from sanctioning organizations describing its prevalence. The present investigation represents a summary of the data collected between December 2015 and January 2018 by the California State Athletic Commission. In total, 512 professional mixed martial artists (455 males and 57 females) were included. Of these, 503 (98%) athletes gained body mass between weigh-in and their bouts. Total RWG between weigh-in and competition was 5.5 ± 2.5 kg, corresponding to an 8.1% ± 3.6% body mass increase. Total RWG was 5.6 ± 2.5 kg (8.1% ± 3.6%) for males and 4.5 ± 2.3 kg (8.0% ± 3.8%) for females. More than one quarter of men and one third of women gained >10% body mass between weigh-in and competition. Athletes from leading international promotions gained more absolute, but not relative, body mass than those from regional promotions. Our findings indicate RWG is nearly ubiquitous in professional , with a similar prevalence in male and female athletes. Trends based on promotion suggest a larger magnitude of RWG in presumably more experienced and/or successful mixed martial artists from leading international promotions.

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.

The Relationship Between Fighting Style, Cognition, and Regional Brain Volume in Professional Combatants: A Preliminary Examination Using Brief Neurocognitive Measures.

OBJECTIVE: Repetitive head impacts (RHIs) in combat sports are associated with cognitive decline and brain volume reduction. While fighting style differences between boxers, mixed martial artists (MMAs), and martial artists (MAs) have resulted in a broader spectrum of injury, the effects of RHIs on MAs relative to other fighters have not yet been explored. This study aimed to determine a differential effect of fighting style on cognition and brain. SETTING: A large outpatient medical center specializing in neurological care. PARTICIPANTS, DESIGN, AND MAIN MEASURES: In total, 40 MAs, 188 boxers, and 279 MMAs were compared on baseline measures of subcortical regional brain volumes, after controlling for total brain volumes, and cognitive performance. RESULTS: Significant differences between MAs, MMAs, and boxers were observed in subcortical brain structure volumes and cognitive measures. MMAs and MAs consistently had larger volumes and higher scores than boxers. Fighting style significantly moderated the relationship between the number of professional fights and the volumes of various subcortical brain structures and performance on a measure of processing speed at baseline. CONCLUSIONS: Differences in RHIs across fighting styles may be of clinical significance. Exploring changes over time within the MA, boxer, and MMA cohorts may provide insight into longer-term discrepancies in subcortical regional brain volumes and cognitive functioning across fighting styles.

Development of a Mobile Phone App for Measuring Striking Response Time in Combat Sports: Cross-Sectional Validation Study.

BACKGROUND: TReaction is a mobile app developed to determine strike response time at low cost and with easy application in combat sports. However, the validity and accuracy of the response time obtained by the TReaction app has not yet been evaluated. OBJECTIVE: This study aimed to test the validity and reliability of the TReaction app in measuring motor response time in combat sports. METHODS: A total of two athletes performed 59 strikes to assess the response time upon visual stimulus using the TReaction app simultaneously with a high-speed camera. Accuracy of the measure was verified using a computer simulator programmed to discharge visual stimuli and obtain the response time. Pearson correlation, Student t test for dependent samples, and the Bland-Altman analysis were performed. Accuracy was verified using the intraclass correlation coefficient. Effect size (g) and the typical error of measurement (TEM) were calculated. The significance level was set at P<.05. RESULTS: No significant difference (P=.56) was found between both systems. The methods presented a very strong correlation (r=0.993). The magnitude of differences was trivial (g<0.25), and TEM was 1.4%. These findings indicate a high accuracy between the computer screen and the mobile app measures to determine the beginning of the task and the response time. CONCLUSIONS: Our findings suggest that the TReaction app is a valid tool to evaluate the response time in combat sports athletes.

Peripheral Vision in Martial Arts Experts: The Cost-Dependent Anchoring of Gaze.

Research on martial arts has suggested that gaze anchoring is functional for optimizing the use of peripheral visual information. The current study predicted that the height of gaze anchoring on the opponent's body would depend on the potential attacking locations that need to be monitored. To test this prediction, the authors compared high-level athletes in kung fu (Qwan Ki Do), who attack with their arms and legs, with Tae Kwon Do fighters, who attack mostly with their legs. As predicted, the results show that Qwan Ki Do athletes anchor their gaze higher than Tae Kwon Do athletes do before and even during the first attack. In addition, gaze anchoring seems to depend on 3 factors: the particulars of the evolving situation, crucial cues, and specific visual costs (especially suppressed information pickup during saccades). These 3 factors should be considered in future studies on gaze behavior in sports to find the most functional, that is, cost-benefit-optimized, gaze pattern.

Diferencias motoras en atletas cadetes de taekwondo según nivel competitivo / Motor Differences in Cadet Taekwondo Athletes According to Competition Level

El objetivo de este estudio es observar las diferencias entre atletas cadetes de Taekwondo de diferentes niveles competitivos en términos antropométricos, de potencia muscular, flexibilidad y velocidad de reacción. Veinte atletas varones fueron analizados, divididos en dos grupos: medallistas nacionales y no medallistas nacionales. Para cada atleta se tomaron datos antropométricos, de velocidad de reacción, potencia muscular y rango de movimiento articular de la articulación coxofemoral. Los atletas medallistas mostraron valores significativamente menores en altura, envergadura, tiempo de reacción óculo-podal, y tiempo de reacción óculo-manual con mano no dominante; y valores mayores para longitud de piernas, flexión pasiva de cadera, y abducción de cadera tanto activa como pasiva. Las leves diferencias observadas entre grupos en potencia muscular, grasa corporal y flexión activa de cadera no concuerdan con estudios previos. Conocer está información podría ser de interés para los entrenadores para llevar a cabo programas de detección de talentos

The aim of this study was to determine the differences between Taekwondo cadet athletes belonging to different competition levels in terms of anthropometry, legs power, flexibility and reaction time. Twenty male athletes were analysed, divided in two groups: national medallist and non-national medallist. Data of every athlete's anthropometric measurements, reaction speed ability, leg power and hip ROM (range of movement) were taken. Medallist athletes showed significantly lower values for height, arm span, foot reaction time (dominant and non-dominant) and non-dominant hand reaction time; and higher values for leg length, passive hip flexion, active hip abduction and passive hip abduction in ROM tests. Slight differences observed between medallists and non-medallists in leg power (CMJ), body fat (Σ skinfolds) and active hip flexion do not agree with previous studies. Knowing this information could be interesting for coaches in order to carry out talent detection programs

Injury rates in martial arts athletes and predictive risk factors for lower limb injuries.

BACKGROUND: Previous studies attempted to identify possible risk factors for acute and overuse injuries in several sports disciplines such as running, gymnastics or team sports. Given the lack of scientific works focused on risk factors for lower limb injuries in martial arts, the present study was aimed to investigate foot anatomy, anthropometric measures, and other background information as possible risk factors of injury in barefoot athletes practicing judo, karate, kung fu, Thai boxing, or aikido. In addition, the injury rates were evaluated in relation with the different martial art styles. METHODS: One group of 130 martial artists was retrospectively evaluated. Data of three morphological variables of the foot were collected: navicular height (NH), navicular drop (ND), and the rear foot (RF). In addition, each participant filled an interview questionnaire providing the following information: age, sex, body weight, height, Body Mass Index, hours of training per week, the kind of injury occurred to the lower limbs in the preceding year. RESULTS: Of 130 subjects, 70 (53.8%) did not sustain injuries, 35 (27.0%) suffered an acute injury and the remaining 25 (19.2%) reported an overuse injury. No significant differences were observed in the injury rates in relation to style and kind of martial art. Age, training volume and BMI were found as significant predictors of injury, while NH, ND, and RF were not able to predict acute or overuse injury at lower limbs. CONCLUSIONS: The injury rates were similar in karate, judo, kung fu, aikido, and Thai boxing. The foot morphology variables were not related with the presence or absence of acute and overuse injuries. Conversely, older and heavier martial artists, performing more hours of barefoot training, are at higher risk of acute and overuse injury. Athletic trainers should strongly take into account the present information in order to develop more accurate and specific injury prevention programs for martial artists.

Weight Loss Strategies in Combat Sports and Concerning Habits in Mixed Martial Arts.

CONTEXT: Combat sports are typically divided into weight classes, and body-mass manipulation to reach a weight class is commonplace. Previous research suggests that weight loss practices in mixed martial arts (MMA) may be more extreme than in other combat sports. PURPOSE: To investigate the magnitude of weight loss and the prevalence of weight loss strategies in different combat sports. METHODS: Competitors (N = 637) from Brazilian jiu-jitsu, boxing, judo, MMA, Muay Thai/kickboxing, taekwondo, and wrestling completed an online questionnaire seeking information regarding their weight loss practices. RESULTS: Body-mass manipulation was commonly undertaken by all combat-sport athletes, with a particularly high incidence of gradual dieting, increased exercise, and fluid restriction. Skipping meals was higher in taekwondo and wrestling (84%) compared with the other combat sports (∼58%), whereas training in heated rooms and forced oral fluid loss (spitting) was higher in wrestling (83% and 47%, respectively) compared with other combat sports (∼45% and ∼19%, respectively). MMA athletes reported the highest usage of sauna (76%) and water loading (67%) while also reporting the second-highest use of training in rubber/plastic suits (63%). CONCLUSIONS: Body-mass manipulation was present in all combat sports, with the prevalence and magnitude of acute weight loss greater in MMA. The incidence of and practices reported will help support staff be fully aware of the variety of methods these athletes and coaches may use to achieve weight loss. Additionally, the results could aid regulatory bodies in the further development of policies on weight cutting.

The effects of different doses of caffeine on performance, rating of perceived exertion and pain perception in teenagers female karate athletes

ABSTRACT The present study set to examine the effects of different doses of caffeine on performance, rating of perceived exertion (RPE), and pain perception in female teenager athletes of karate. Ten female karate athletes (16.8±1.23 years; height 1.59±0.28 m; body-mass 57.73±8.33 kg; BMI 22.71±3.05 kg/m2) participated in the study. A double-blind, randomized, and crossover counterbalanced design was used. In three sessions (with an interval of seven days'), ten female karate athletes ingested low dose (2 mg/kg), moderate dose (5 mg/kg) caffeine, and placebo. Sixty minutes after consumption, they performed the tests as below: one repetition maximum and 60% of one repetition maximum in the leg press, explosive power test, and anaerobic RAST test. After the tests, the participants' RPE (6-20 scale) and pain perception (0-10 scale) were recorded using various categorical scales. The results showed that caffeine ingestion at moderate dose significantly reduced RPE and pain perception values compared with the placebo during muscular endurance test (P=0.0001 and P=0.039, respectively). The findings suggest that caffeine dose of 5 mg/kg body mass appears to improve RPE and pain perception in female teenager athletes of karate. The dose of 2 mg/kg body mass does not confer any additional improvement in performance.

Fitness and Anthropometric Profiles of International vs. National Judo Medalists in Half-Heavyweight Category.

The aim of the study was to determine the anthropometric and fitness profiles of European half-heavyweight judokas by success in competition. For this purpose, we compared 5 international medalists (elite) with 5 national medalists (subelite). All male judokas won at least 1 medal in the half-heavyweight category during the previous 2 years. The testing in this cross-sectional study was performed during 4 days. All subjects underwent anthropometric assessment with body mass, height, skinfold, and limb circumference measures, and the body fat percentage was estimated by manual bioimpedance. The physical fitness evaluation consisted in peak torques for thigh and shoulder muscles, handgrip strength, high and long jumps, medicine ball throw, pull-ups, deadlift, bench press, deep squat, V[Combining Dot Above]O2max, Max Power, and Tokui Waza tests. The statistical analysis by the Student's t test showed significant differences for forearm and upper-arm circumferences, peak torques, pull-ups, bench press, deadlift, deep squat, V[Combining Dot Above]O2max, Max Power, and Tokui Waza tests. Our results showed that elite judokas have a superior fitness profile than subelite athletes from the half-heavyweight category. Moreover, elite judokas seem to have a higher arm muscle mass than subelite athletes but a similar body fat percentage. This study could be of interest for judo coaches with athletes competing in the half-heavyweight category, as some tests that discriminate by judo success for this specific weight category are described. Few studies analyze anthropometric and fitness profiles in half-heavyweight male judokas, so additionally our results can be used as a reference for coaches, athletes, and scientists.

Optimal load for the peak power and maximal strength of the upper body in Brazilian Jiu-Jitsu athletes.

We determined the optimal load for the peak power output (PPO) during the bench press throw (BPT) in Brazilian Jiu-Jitsu (BJJ) athletes and compared the PPO and maximal strength between advanced (AD) and nonadvanced (NA) athletes. Twenty-eight BJJ athletes (24.8 ± 5.7 years) performed the BPT at loads of 30, 40, 50, and 60% of their 1 repetition maximum (RM) in a randomized order (5-minute rest between BPTs). The PPO was determined by measuring the barbell displacement by an accelerometer (Myotest). The absolute (F = 7.25; p < 0.001; effect size [ES] = 0.21) and relative intensities were different (F = 7.11; p < 0.001; ES = 0.21) between the AD and NA. There was also a group and intensity interaction effect (F = 2.79; p = 0.046; ES = 0.10), but the differences were centered around the AD group, which achieved higher values using 40% (p = 0.001) and 50% of the 1RM (p < 0.001) than the PPO with 60% of 1RM. The AD athletes presented with higher 1RM than NA (p ≤ 0.05; ES = 1.0), but there was no difference (p > 0.05) in the PPO (30-60% 1RM). A polynomial adjustment indicated that the optimal load was ∼42% of 1RM for all groups and subgroups (R from 0.82 to 0.99). Our results suggest that there can be (1RM) differences between AD and NA BJJ athletes; however, there is no difference in the muscle power between the AD and NA groups. Additionally, ∼42% of 1RM seems to be the optimal load for developing maximal power using the BPT for the BJJ athletes.

Evaluación de la atención en deportistas de artes marciales. Expertos vs. novatos / Measuring attention in martial art athletes. Experts versus novices / Avaliação da atenção em desportistas de artes marciais: especialistas vs. iniciantes

El objetivo del estudio fue determinar las diferencias en el desempeño de una tarea de atención en relación con la pericia en artes marciales. Participaron 12 deportistas de artes marciales expertos y 13 novatos. Se les aplicó el Test of Variables of Attention (Greenberg, 1996) y se analizaron los datos de la prueba para cada variable, condición y segmentos en los que se divide, con un método estadístico no-paramétrico de permutaciones. Las comparaciones intergrupos indicaron una tendencia a que el puntaje global de Trastorno por Déficit de Atención e Hiperactividad (TDAH) de la prueba fuera mejor en los expertos que en los novatos. Se hizo un análisis intragrupo para conocer el comportamiento de cada grupo a lo largo de la prueba; los resultados indicaron que los deportistas expertos muestran mayor consistencia en el número de aciertos y tiempos de reacción a lo largo de la prueba, lo que se traduce como un mejor desempeño cuando se compara con la forma en que los deportistas novatos responden a la tarea. Los resultados sugieren que el entrenamiento físico y mental de las disciplinas de artes marciales podría producir una mejora en las capacidades de atención de los deportistas

The aim of this study is to determine differences in the performance of an attention-related task involving martial arts skills. 12 expert martial arts athletes and 13 novices took part, performing the Test of Variables of Attention (Leark, Greenberg, Kindschi, Dupuy and Hughes, 2007). Using a non-parametric statistical permutation method, the test data for each variable, condition and segment of the test was analysed. Comparisons of the groups showed a trend toward a higher global Attention Deficit Hyperactivity Disorder (ADHD) score by the expert athletes as compared with the novices. In order to find out each group’s performance during the test, a statistical intra-group analysis was performed. Generally, the results revealed more consistent accuracy and response times by the experts than by the novice athletes. The results suggest that physical and mental training in the martial arts may increase the attention skills of sportsmen and women

O objectivo do estudo foi determinar as diferenças no desempenho de uma tarefa atencional tendo em conta a perícia em artes marciais. Participaram no estudo 12 desportistas especialistas em artes marciais e 13 iniciantes. Foi aplicado aos participantes o Test of Variables of Attention (Greenberg, 1996) e analisaram-se os dados do teste para cada variável, condição e segmentos em que se dividem, através de um método estatístico nãoparamétrico de permutações. As comparações intergrupos indicaram uma tendência para que a pontuação global de Transtorno do Défice de Atenção e Hiperactividade (TDAH) fosse maior nos especialistas do que nos iniciantes. Foi realizada uma análise intragrupo para conhecer o comportamento de cada grupo ao longo da prova; os resultados indicaram que os desportistas especialistas revelaram maior consistência no número de acertos e tempos de reacção ao longo da prova, o que se traduz num melhor desempenho quando comparados com a forma como os desportistas iniciantes respondem à tarefa. Os resultados sugerem que o treino físico e mental das disciplinas de artes marciais poderia produzir uma melhoria nas capacidades atencionais dos desportistas

Epidemiology of injuries in elite taekwondo athletes: two Olympic periods cross-sectional retrospective study.

OBJECTIVE: Taekwondo injuries differ according to the characteristics of the athletes and the competition. This analytical cross-sectional retrospective cohort study aimed to describe reported taekwondo injuries and to determine the prevalence, characteristics and possible risk factors for injuries sustained by athletes of the Spanish national team. In addition, we compared each identified risk factor-age, weight category, annual quarter, injury timing and competition difficulty level-with its relation to injury location and type. SETTINGS: Injury occurrences in taekwondo athletes of the Spanish national team during two Olympic periods at the High Performance Centre in Barcelona were analysed. PARTICIPANTS: 48 taekwondo athletes (22 male, 26 female; age range 15-31 years) were studied; 1678 injury episodes occurred. Inclusion criteria were: (1) having trained with the national taekwondo group for a minimum of one sports season; (2) being a member of the Spanish national team. RESULTS: Independently of sex or Olympic period, the anatomical sites with most injury episodes were knee (21.3%), foot (17.0%), ankle (12.2%), thigh (11.4%) and lower leg (8.8%). Contusions (29.3%) and cartilage (17.6%) and joint (15.7%) injuries were the prevalent types of injury. Chronological age, weight category and annual quarter can be considered risk factors for sustaining injuries in male and female elite taekwondists according to their location and type (p≤0.001). CONCLUSIONS: This study provides epidemiological information that will help to inform future injury surveillance studies and the development of prevention strategies and recommendations to reduce the number of injuries in taekwondo competition.

Fase do treinamento esportivo não afeta a variabilidade da frequência cardíaca em atletas de jiu-jitsu / Phase of sports training does affect the heart rate variability in a athletes of jiu-jitsu

O objetivo desse estudo foi avaliar a modulação autonômicacardíaca de atletas de jiu-jitsu, comparando-os com sedentáriose avaliando as alterações dessa modulação ao longo dasdiferentes fases de treinamento. Foram avaliados sete atletas esete indivíduos sedentários do sexo masculino (23 ± 4 e 24 ± 3anos, respectivamente). A frequência cardíaca (FC) e o sinalrespiratório foram coletados por 10 minutos na posição deitadaem três fases do treinamento dos atletas (preparatória, competitivae transitória) e num único momento nos sedentários.A modulação autonômica cardíaca foi avaliada pela análiseespectral da variabilidade da FC (VFC) utilizando-se o modeloautorregressivo. A comparação entre os grupos foi feitapelos testes t não pareado ou Mann-Whitney. A comparaçãoentre as fases de treinamento no grupo de atletas foi realizadapela ANOVA de um fator para amostras repetidas (p < 0,05).Os grupos apresentaram características físicas e funcionaissemelhantes, mas a força máxima foi significantemente maiornos atletas. Todos os índices de VFC foram semelhantes entreos atletas e os sedentários. Além disso, esses índices não sealteraram significantemente entre as fases preparatória, competitivae transitória do treinamento dos atletas. Em conclusão, osatletas de jiu-jitsu apresentam modulação autonômica cardíacasemelhante à de sedentários, e essa modulação não se alteranas diferentes fases de periodização do treinamento.

The aim of this study was to evaluate cardiac autonomic modulationin jiu-jitsu athletes, comparing with sedentary individuals,and evaluating changes that may happen throughout the differentphases of training. Seven athletes and seven sedentary males (23± 4 e 24 ± 3 years, respectively) were evaluated. Heart rate (HR)and respiratory signal were collected for 10 min in the supineposition in the three phases of training (preparatory, competitiveand transient) in the athletes and at one moment in the sedentarysubjects. Cardiac autonomic modulation was evaluated by thespectral analysis of HR variability (HRV) using the autoregressivemodel. Comparisons between groups were performed byunpaired t-test or Mann-Whitney test. Comparisons among thetraining phases were performed by one-way ANOVA for repeatedmeasures (p < 0.05). Athletes and sedentary subjects presentedsimilar physical and cardiovascular characteristics, althoughmaximal strength was significantly higher in the athletes. All ofthe HRV indexes were similar between athletes and sedentarysubjects. In addition, HRV indexes did not change among thepreparatory, competitive and transition phases of training. Inconclusion, jiu-jitsu athletes have cardiac autonomic modulationsimilar to sedentary subjects and this modulation is not changedthroughout the different periodization phases of training.

Home advantage in judo: a study of the world ranking list.

In 2009, the International Judo Federation established a ranking system (RS) to classify athletes and to distribute the competitor quotas of the Olympic Games. However, the RS does not consider the home advantage. This issue has not been studied in judo, and its implications for the RS have not been determined. The objective was to verify the home advantage in judo in terms of winning a medal or the number of matches won. Therefore, 25 competitions that computed points for the RS in 2009 were analysed. Logistic regression analysis and the Poisson generalised linear model were used for the analyses, which included the relative quality of the athletes. The sample was composed only of athletes who had competed both at home and away. The odds ratio for winning medals was higher for athletes who competed at home for both males and females. The association between the number of matches won and competing at home was significant only for the male athletes. The home advantage was observed in the competitions that used the judo RS. Thus, it is likely that athletes from countries that host competitions using the RS have an advantage in terms of obtaining their Olympic classification.

Development, validity and reliability of a questionnaire designed to evaluate rapid weight loss patterns in judo players.

The aim of this study was to develop a questionnaire to evaluate rapid weight loss patterns of competitive judo players and to assess its validity and reliability. We evaluated the reliability (n=94), content validity (evaluation by 10 experts), discriminant validity (differences in scores between athletes with body weight below and above their weight class; n=100) and convergent validity (correlation with Restraint Scale; n=60). No item was considered unclear or ambiguous by more than 20% of the experts. The intraclass Coefficient Correlation was above 0.90 for all questions whose answers were parametric (P<0.001; n=94) and no significant differences were found between test and retest scores (n=94--Wilcoxon's signed rank test). Cronbach's alpha was 0.98 for scores obtained between test and retest. Non-numerical questions showed proportions of agreement >80%; Spearman's Correlation between the Restraint Scale and the Rapid Weight Loss Questionnaire was 0.62 (P<0.001; n=60). Athletes below their weight class (n=50) had a significantly lower score compared with athletes above the weight class (n=50; P<0.001--Mann-Whitney U test). In conclusion, the questionnaire showed good validity and reliability and could be used accurately to assess weight loss patterns of judo players.

Characteristics of martial art injuries in a defined Canadian population: a descriptive epidemiological study.

BACKGROUND: The martial arts have emerged as common activities in the Canadian population, yet few studies have investigated the occurrence of associated injuries on a population basis. METHODS: We performed such an investigation and suggest potential opportunities for prevention. The data source was 14 years (1993 to 2006) of records from the Kingston sites of the Canadian Hospital Injury Reporting and Prevention Program (CHIRPP). RESULTS: 920 cases were identified. Incidence rates were initially estimated using census data as denominators. We then imputed annual injury rates per 10000 using a range of published estimates of martial arts participation available from a national survey. Rates of injury in males and females were 2300 and 1033 per 10000 (0.3% participation) and 575 and 258 per 10000 (1.2% participation). Injuries were most frequently reported in karate (33%) and taekwondo (14%). The most common mechanisms of injury were falls, throws and jumps (33%). Fractures (20%) were the most frequently reported type of injury and the lower limb was the most common site of injury (41%). CONCLUSIONS: Results provide a foundation for potential interventions with a focus on falls, the use of weapons, participation in tournaments, as well as head and neck trauma.

Force, reaction time, and precision of Kung Fu strikes.

The goal was to compare values of force, precision, and reaction time of several martial arts punches and palm strikes performed by advanced and intermediate Kung Fu practitioners, both men and women. 13 Kung Fu practitioners, 10 men and three women, participated. Only the men, three advanced and seven intermediate, were considered for comparisons between levels. Reaction time values were obtained using two high speed cameras that recorded each strike at 2500 Hz. Force of impact was measured by a load cell. For comparisons of groups, force data were normalized by participant's body mass and height. Precision of the strikes was determined by a high speed pressure sensor. The results show that palm strikes were stronger than punches. Women in the study presented, on average, lower values of reaction time and force but higher values of precision than men. Advanced participants presented higher forces than intermediate participants. Significant negative correlations between the values of force and precision and the values of force and reaction time were also found.

Injuries in martial arts: a comparison of five styles.

OBJECTIVE: To compare five martial arts with respect to injury outcomes. METHODS: A one year retrospective cohort was studied using an injury survey. Data on 263 martial arts participants (Shotokan karate, n = 114; aikido, n = 47; tae kwon do, n = 49; kung fu, n = 39; tai chi, n = 14) were analysed. Predictor variables included age, sex, training frequency (3 h/week), experience (<3 years v >or=3 years), and martial art style. Outcome measures were injuries requiring time off from training, major injuries (>or=7 days off), multiple injuries (>or=3), body region, and type of injury. Logistic regression was used to determine odds ratios (OR) and confidence intervals (CI). Fisher's exact test was used for comparisons between styles, with a Bonferroni correction for multiple comparisons. RESULTS: The rate of injuries, expressed as percentage of participants sustaining an injury that required time off training a year, varied according to style: 59% tae kwon do, 51% aikido, 38% kung fu, 30% karate, and 14% tai chi. There was a threefold increased risk of injury and multiple injury in tae kwon do than karate (p<0.001). Subjects >or=18 years of age were at greater risk of injury than younger ones (p<0.05; OR 3.95; CI 1.48 to 9.52). Martial artists with at least three years experience were twice as likely to sustain injury than less experienced students (p<0.005; OR 2.46; CI 1.51 to 4.02). Training >3 h/week was also a significant predictor of injury (p<0.05; OR 1.85; CI 1.13 to 3.05). Compared with karate, the risks of head/neck injury, upper extremity injury, and soft tissue injury were all higher in aikido (p<0.005), and the risks of head/neck, groin, and upper and lower extremity injuries were higher in tae kwon do (p<0.001). No sex differences were found for any of the outcomes studied. CONCLUSIONS: There is a higher rate of injury in tae kwon do than Shotokan karate. Different martial arts have significantly different types and distribution of injuries. Martial arts appear to be safe for young athletes, particularly those at beginner or intermediate levels.