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.

Safety recommendations in Shotokan karate.

OBJECTIVE: To study risk factors for injury in karate and to establish safety recommendations. DESIGN: Cross-sectional survey of karate injuries. SETTING: Shotokan karate clubs in Boston, Massachusetts, Dallas, Texas, and Winnipeg, Manitoba, Canada. PARTICIPANTS: All athletes training at each club received surveys. A total of 114 surveys were analyzed (74% response rate). MAIN OUTCOME MEASURES: Presence of injuries (requiring any time off from practice), major injuries (requiring at least 7 days off), and multiple injuries (3 or more injuries). RESULTS: No statistically significant differences were found with respect to sex. For all outcomes, karateka younger than 18 years of age had fewer injuries. The number of karateka with injuries and with multiple injuries increased with belt rank until brown belt, then reached a plateau. Brown and black belts had a greater frequency of major injuries than the lower ranks. Training more than 3 hours per week correlated with an increase in injuries, major injuries, and multiple injuries. CONCLUSION: Shotokan karate appears to be a safe sport, especially for those younger than 18 years of age. Risk of injury increases significantly when younger karateka of any rank or older karateka of lower ranks train more than 3 hours per week; therefore, to reduce the risk of injury to less than 50%, weekly training should be limited to a maximum of 3 hours in these groups.

Karate injuries in children and adolescents.

OBJECTIVES: To identify risk factors for injury and to establish safety guidelines for children in Uechi-Ryu karate. DESIGN: A 1-year retrospective survey of injuries. SETTING: A private karate school (Uechi-Ryu style) in Plymouth, MA. PATIENTS: A total of 68 athletes (age 6-16 years; mean age 10 years) who participated in karate during the 1995-1996 season. INTERVENTIONS: None. MAIN OUTCOME MEASURES: The presence or absence of injury, with grading of injuries as major, moderate or minor. The types of injuries and body region involved were also analyzed. RESULTS: Twenty eight percent of athletes sustained at least one injury. All injuries were minor, with no time off from training required. The injuries consisted primarily of bruises (11 of 19). Other injuries included mild sprains or strains (5 of 19) and having their 'wind knocked out' (3 of 19). Most injuries were localized to the extremities. Logistic regression analysis identified risk factors for injury. Risk of injury increased with number of years of training (odds ratio 2.95; 95% confidence interval 1.81-4.82; P<0.0001), number of hours per week (odds ratio 2.12; CI 1.15-4.21; P = 0.016) and rank, specifically brown belt versus lower belts (odds ratio 6.56; CI 2.02-21.26; P = 0.006). CONCLUSIONS: Karate is a relatively safe sport for children and adolescents when properly taught. Risk of injury increases with experience; therefore, greater supervision is required of higher ranks. Injury increases with weekly training; however, 3 h a week or less appears to be associated with a low risk of significant injury in this age group.

Effects of prior exercise on eccentric exercise-induced neutrophilia and enzyme release.

PURPOSE: The purpose of this study was to determine the effects of prior exercise on changes in circulating neutrophils, neutrophil activation, and myocellular enzymes following a standardized bout of eccentric exercise. METHODS: Twenty-four male volunteers were randomized into three groups (N = 8). Group C performed 10 sets of 10 eccentric contractions of the quadriceps muscles with both legs (100% of the concentric IRM). Group D and Group F exercised for 2 h at 56%VO2max on a cycle ergometer followed by a similar bout of eccentric contractions. Group F also received 7.5 mL x kg(-1) of a carbohydrate-electrolyte beverage every 30 min during the submaximal exercise, whereas group D received no fluid. RESULTS: Body weight remained unchanged in groups C and F and decreased in group D by 1.56 +/- 0.34 kg. Ultrastructural Z-Band damage increased three-fold following exercise and remained elevated 3 d after exercise but was not different among groups. Circulating neutrophils were elevated more in group D compared with those in group C immediately after the exercise or rest period, and this difference persisted 3 h after the eccentric exercise. Serum lactoferrin concentrations increased 3.3-fold after exercise in all groups (P < 0.01). Creatine kinase levels (CK) rose in all subjects, with subjects in Group F and D having a significantly greater rise in CK after exercise compared with those in group C. CONCLUSIONS: These data indicate that submaximal exercise followed by a bout of eccentric exercise results in similar amounts of myofibrillar injury with a larger neutrophil response and CK release.

Exercise stimulates the mitogen-activated protein kinase pathway in human skeletal muscle.

Physical exercise can cause marked alterations in the structure and function of human skeletal muscle. However, little is known about the specific signaling molecules and pathways that enable exercise to modulate cellular processes in skeletal muscle. The mitogen-activated protein kinase (MAPK) cascade is a major signaling system by which cells transduce extracellular signals into intracellular responses. We tested the hypothesis that a single bout of exercise activates the MAPK signaling pathway. Needle biopsies of vastus lateralis muscle were taken from nine subjects at rest and after 60 min of cycle ergometer exercise. In all subjects, exercise increased MAPK phosphorylation, and the activity of its downstream substrate, the p90 ribosomal S6 kinase 2. Furthermore, exercise increased the activities of the upstream regulators of MAPK, MAP kinase kinase, and Raf-1. When two additional subjects were studied using a one-legged exercise protocol, MAPK phosphorylation and p90 ribosomal S6 kinase 2, MAP kinase kinase 1, and Raf-1 activities were increased only in the exercising leg. These studies demonstrate that exercise activates the MAPK cascade in human skeletal muscle and that this stimulation is primarily a local, tissue-specific phenomenon, rather than a systemic response to exercise. These findings suggest that the MAPK pathway may modulate cellular processes that occur in skeletal muscle in response to exercise.