Willy Pieter

Physical and Physiological Profiles of Taekwondo Athletes

Taekwondo has evolved into a modern-day Olympic combat sport. The physical and physiological demands of modern-day taekwondo competition require athletes to be competent in several aspects of fitness. This review critically explores the physical and physiological characteristics of taekwondo athletes and presents implications for training and research. International taekwondo athletes possess low levels of body fat and a somatotype that characterises a blend of moderate musculoskeletal tissue and relative body linearity. While there is some variation in the maximum oxygen uptake of taekwondo athletes, moderate to high levels of cardio-respiratory fitness are necessary to support the metabolic demands of fighting and to facilitate recovery between consecutive matches. Taekwondo athletes demonstrate high peak anaerobic power characteristics of the lower limbs and this attribute appears to be conducive to achieving success in international competition. The ability to generate and sustain power output using both concentric and ‘stretch-shortening cycle’ muscle actions of the lower limbs may be important to support the technical and tactical actions in combat. Taekwondo competitors also display moderate to high maximum dynamic strength characteristics of the lower and upper extremities, and moderate endurance properties of the trunk and hip flexor musculature. The dynamic nature of the technical and tactical actions in the sport demand high flexibility of the lower limbs. More extensive research is required into the physical and physiological characteristics of taekwondo athletes to extend existing knowledge and to permit specialised conditioning for different populations within the sport.

Effects of Olympic-style taekwondo kicks on an instrumented head-form and resultant injury measures

Objective The objective of this study was to assess the effect of taekwondo kicks and peak foot velocity (FVEL) on resultant head linear acceleration (RLA), head injury criterion (HIC15) and head velocity (HVEL). Methods Each subject (n=12) randomly performed five repetitions of the turning kick (TK), clench axe kick (CA), front leg axe kick, jump back kick (JB) and jump spinning hook kick (JH) at the average standing head height for competitors in their weight division. A Hybrid II Crash Test Dummy head was fitted with a protective taekwondo helmet and instrumented with a triaxial accelerometer and fixed to a height-adjustable frame. Resultant head linear acceleration, HVEL, FVEL data were captured and processed using Qualysis Track Manager. Results The TK (130.11±51.67u2005g) produced a higher RLA than the CA (54.95±20.08u2005g, p<0.001, d=1.84) and a higher HIC15 than the JH (672.74±540.89 vs 300.19±144.35, p<0.001, ES=0.97). There was no difference in HVEL of the TK (4.73±1.67u2005m/s) and that of the JB (4.43±0.78u2005m/s; p=0.977, ES<0.01). Conclusions The TK is of concern because it is the most common technique and cause of concussion in taekwondo. Future studies should aim to understand rotational accelerations of the head.

ENERGY ABSORBED BY ELECTRONIC BODY PROTECTORS FROM KICKS IN A TAEKWONDO COMPETITION

Objective: Although some scientific information on electronic body protectors in taekwondo is available, no research has been done to assess the impact of kicks in a competitive situation. The purpose of this study, then, was to assess the energy absorbed by these protectors from kicks performed in an actual taekwondo competition. Methods: Subjects consisted of junior (14-17 years) and senior (≥18 years) male taekwondo-in, who participated in an open tournament. Data on the energy imparted by valid kicks in Joules (J) were collected from a public visual electronic monitor. Results: Energy was higher for the seniors: 264.31 ± 56.63 J versus 224.38 ± 48.23 J for the juniors (eta 2 = 0.121). The seniors scored lower in percent impact but the effect was trivial: 123.46 ± 24.77% versus 136.70 ± 26.33% (eta 2 = 0.087). Conclusions: The difference between senior and junior taekwondo-in in absolute energy generated was small, while the difference in relative energy impact was trivial in favour of the junior taekwondo athletes.

Safety performance evaluation of taekwondo headgear

Background With over 20u2005years of taekwondo concussion research highlighting the high incidence of injury, previous studies recommend an investigation of headgear impact attenuation performance. Objective To examine impact attenuation differences between the anterior, posterior and sides of selected taekwondo headgear brands. Design Between-groups. Setting Biomechanics laboratory. Methods Five different commercially available taekwondo headgear were selected for impact testing. A 50th percentile Hybrid II Dummy Crash Test head and neck was fitted with the selected helmet and was bolted to a 25u2005kg steel torso-like structure. Each headgear model was impacted eight times to the anterior, posterior and sides by a 6.75u2005kg bowling ball at three heights to produce 52.25, 85 and 144u2005J strikes. Main outcome measurements Resultant head linear acceleration. Results Two-way (Helmet×Location) mixed analysis of variance with repeated measures on the second factor was performed to determine the differences between headgear by location of impact. There was a two-way (Helmet×Location) interaction for acceleration (η2=0.368). Conclusions Taekwondo headgear manufacturers and sport governing bodies must consider improving the design of especially anterior helmet properties.

Mediating factors in martial arts and combat sports: an analysis of the type of martial art, characteristics, and social background of young participants

To date, most studies regarding the social-psychological effects of martial arts and combat sports (MA&CS) on young people focus on measuring effects without considering mediating factors. The aim of the present study was to analyze three mediating factors that might be influential when examining outcomes of MA&CS for youth (i.e., the type of MA&CS, participants characteristics, and social background). Young MA&CS participants (N = 477, M age = 14.0 yr., SD = 2.13) practicing judo, aikido, kick-/Thai boxing or karate, as well as their parents (N = 307), were assessed in terms of their goal orientations, aggressiveness, psychosocial behavior, and social background. It was concluded that differences exist in the characteristics and social background of participants depending on the type of MA&CS being practiced. The fact that differences in these mediating factors can be identified indicates that in future research these and possible other mediating factors should be considered when trying to determine social-psychological outcomes of MA&CS.

BIOMECHANICS OF HEAD INJURY IN OLYMPIC TAEKWONDO AND BOXING

Objective The purpose was to examine differences between taekwondo kicks and boxing punches in resultant linear head acceleration (RLA), head injury criterion (HIC15), peak head velocity, and peak foot and fist velocities. Data from two existing publications on boxing punches and taekwondo kicks were compared. Methods For taekwondo head impacts a Hybrid II Crash Dummy (Hybrid II) head was instrumented with a tri-axial accelerometer mounted inside the Hybrid II head. The Hybrid II was fixed to a height-adjustable frame and fitted with a protective taekwondo helmet. For boxing testing, a Hybrid III Crash Dummy head was instrumented with an array of tri-axial accelerometers mounted at the head centre of gravity. Results Differences in RLA between the roundhouse kick (130.11±51.67 g) and hook punch (71.23±32.19 g, d = 1.39) and in HIC15 (clench axe kick: 162.63±104.10; uppercut: 24.10±12.54, d = 2.29) were observed. Conclusions Taekwondo kicks demonstrated significantly larger magnitudes than boxing punches for both RLA and HIC.

IMPACT ATTENUATION OF PROTECTIVE BOXING AND TAEKWONDO HEADGEAR

Background To date, only one study reported the impact attenuation of protective taekwondo headgear. Although Olympic boxing has discontinued the use of headgear, similarities in designs are thought to provide a framework for improvements of taekwondo headgear. Objective To determine differences in impact attenuation of taekwondo and boxing headgear. Design Between groups. Setting Impact biomechanics laboratory. Participants World Taekwondo Federation (WTF) and Amateur International Boxing Association (AIBA) approved protective headgear. Risk factor assessment A standardized (ASTM F-2397) martial arts headgear striker was used to impart impacts to a 50th Percentile Male Hybrid III Dummy head and neck complex. All impacts were imparted with a terminal striking velocity of 5.0u2005m/s (min - max=4.75 −5.15m/s). 2 AIBA-approved headgear (Adidas and Green Hills) and 2 WTF-approved headgear were selected for testing. Each headgear model was fitted to the Hybrid III and impacted a total of 5 times to the left side (temporal) of the headgear along an ASTM-specified impact region. As per ASTM standards low velocity impacts must yield head RLAs below 50g. Main outcome measurements Resultant linear acceleration (RLA). Results 1-way ANOVA showed significant differences between the headgear brands (eta2=0.928). The most protection was provided by the taekwondo Adidas headgear (60.5±4.3g) followed by the boxing Adidas (75.4±9.9g), boxing Greenhill (109.4±10.11g), and taekwondo Nike headgear (129.5±8.2g). The greatest difference in RLA was observed between the two taekwondo models (d=−9.54, 95% CI=−13.91 – −5.18), whereas the smallest clinically meaningful difference was observed between the two Adidas models (d=−1.94, 95% CI=−3.20 – −0.29). Conclusions Each of the headgear brands performed differently under the testing conditions. All models need to be redesigned to mitigate low velocity impacts. Future testing must include impacts at high impact velocities.

Diminished impact attenuation properties of taekwondo and boxing headgear

Background Only one study reported the impact attenuation of taekwondo headgear. Although Olympic boxing has discontinued the use of head protectors, similarities in designs are suggested to provide a framework for improving taekwondo helmets as a previous report determined poor testing results. Objective To assess attenuation of taekwondo and boxing headgear. Design Between-groups. Setting: Impact biomechanics laboratory. Participants Helmets approved by the World Taekwondo Federation and those by the International Boxing Association. Risk Factor assessement A standardized (ASTM F-2397) martial arts headgear striker was used to impart impacts to a 50th Percentile Male Hybrid III Dummy (Hybrid III) head and neck complex. All impacts were imparted with a terminal striking velocity of 5.0u2005m/s (max-min=5.15–4.75u2005m/s). Each headgear model (boxing: Adidas and Green Hills; taekwondo: Adidas and Nike) were fitted to the Hybrid III and impacted a total of 60 times to the left side of the headgear. Main outcome measurements Resultant linear acceleration (RLA). Results There was a significant difference in RLA between helmets (eta2=0.963, 95% CI: 0.881–0.987). Pairwise comparisons showed differences between the taekwondo Nike (129.48±8.18g) and boxing Green Hills helmets (109.48±10.11g) (d=2.19, 95% CI: –4.98–11.05). The boxing Adidas helmet (75.42±9.99g) recorded a higher RLA than its taekwondo counterpart (d=2.09, 95% CI: −6.67–5.82). Conclusions Both boxing and taekwondo helmets have a limited lifespan.

THE EFFECT OF PROTECTIVE TAEKWONDO FOOTPADS ON ATTENUATING IMPACTS OF AN INSTRUMENTED HEAD-FORM

Background A recent regulation in boxing, of removing headgear, proposes the question as to whether a similar rule should be adopted in taekwondo. Objective To assess the effect of protective taekwondo footpads on attenuating impacts of an instrumented head-form. It is hypothesised that footpads with greater thickness would mitigate impacts better than thinner ones. Design Between groups. Setting Impact biomechanics laboratory. Participants World Taekwondo Federation approved protective footpads. Risk factor assessment A standardized (ASTM F-2397) martial arts headgear striker was used to impart impacts to a 50th Percentile Male Hybrid III head and neck complex. All impacts were imparted with a terminal striking velocity of 5.0u2005m/s (min-max: 4.75–5.15u2005m/s). Six different striking conditions were employed (no footpad (control), KDS, Adidas, Mooto, Mooto MTX, old style footpad [i.e., thick]). Each footpad condition was tested for a total of 3 impacts. The level of significance was set to an effect size of 0.2. Main outcome measurements Resultant linear acceleration (RLA). Results Significant differences were found between all footpads (eta2=0.86). The most effective impact attenuation was provided by the old style footpad (102g), followed by the Adidas (124g), KDS (140g), Mooto (140g), MTX (149g), and non-footpad condition (211g). The greatest difference in RLA was observed between the thick footpad and the non-padded condition (102u2005g v 211u2005g, d=2.08, 95% CI=-0.19–3.51). Conclusions The footpads when compared with the control condition did decrease the RLA but not to an ASTM standard of 50g. These results do not support the removal of protective taekwondo headgear. Future studies may investigate the use of better designed footpads if a similar regulation were to be adopted.