Rotational and linear head accelerations from taekwondo kicks and punches.

The purpose was to compare rotational and linear head accelerations as a result of taekwondo kicks and punches. Taekwondo athletes executed five repetitions of the turning kick, spinning hook kick, hook punch, straight punch, and jab punch to a Hybrid III Crash Test Dummy head-neck complex. A tri-axial accelerometer and an angular rate sensor were mounted inside the Hybrid III head to measure resultant linear (RLA) and rotational accelerations. The Hybrid III was fixed to a height-adjustable frame and fitted with protective taekwondo headgear. Dummy head height was positioned to each participant's standing height. Acceleration data were processed in accordance with SAE J211-1.There was no significant multivariate difference in RLA but the effect was not clear. Univariate follow-up analysis showed a significant difference in RLA but the effect was also not clear. There was no difference in rotational acceleration. The highest RLA and rotational acceleration were produced, in order, by the turning kick, hook kick, hook punch, straight punch, and jab. These data are clinically important as they provide a better understanding of the biomechanical injury measures and support for improved headgear testing methodology.

Biomechanical head impact characteristics during sparring practice sessions in high school taekwondo athletes.

OBJECTIVE The purpose of this study was to monitor head impact magnitude and characteristics, such as impact location and frequency, at high school taekwondo sparring sessions. METHODS Eight male high school taekwondo athletes participated in this study. The head impact characteristics were recorded by X-Patch, a wireless accelerometer and gyroscope, during 6 taekwondo sparring sessions. The outcome measures were the peak linear acceleration ( g = 9.81 msec2), peak rotational acceleration, rotational velocity, and Head Injury Criterion. RESULTS A total of 689 impacts occurred over 6 sessions involving the 8 athletes. There was an average of 24 impacts per 100 minutes, and there were significant differences in the frequency of impacts among both the sessions and individual athletes. In order of frequency, the most commonly hit locations were the side (38.2%), back (35.7%), and front (23.8%) of the head. CONCLUSIONS The data indicate that there is a relatively high number of head impacts experienced by taekwondo athletes during sparring practice. According to the rotational acceleration predicting impact severity published in previous research, 17.1% of the impacts were deemed to be a moderate and 15.5% were deemed to be severe.

Impact attenuation of protective boxing and taekwondo headgear.

This study aimed to compare the impact attenuation performance of boxing and taekwondo headgear in terms of peak linear and rotational acceleration. To measure the impact attenuation of headgear, a standardized (American Society for Testing and Materials (ASTM) F-2397) martial arts headgear striker was used to impart impacts to a 50th Percentile Male Hybrid III Crash Test Dummy head and neck complex. Two boxing (Adidas and Greenhill) and two taekwondo (Adidas and Nike) headgear, approved by the Association Internationale de Boxe Amateur and the World Taekwondo Federation (WTF), were selected. Each of the selected headgear was fitted to the Hybrid III head and subsequently subjected to five impacts at the front and side with a maximum impact interim time of 60 seconds by the rotating striker at 8 ± 0.3 m/s. Linear and rotational acceleration were recorded at 10,000 Hz. There were significant interactions of the impact location and brand on the rotational acceleration, F(3,40) = 6.7, p < .05. There were significant main effects of both impact location F(1,40) = 9.07, p < .05 and headgear brand F(3,40) = 9.9, p < .05 on the linear acceleration. Pairwise comparisons show significant differences between the front and side for both linear and rotational acceleration. The headgear tested failed the ASTM high impact test requirement to reduce the linear acceleration to below a threshold of 150 g. Further development of headgear to reduce impact linear and rotational acceleration magnitudes should be called for by the relevant sport governing bodies and initiated by headgear manufactures.

Safety performance evaluation of taekwondo headgear.

BACKGROUND: With over 20 years 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 25 kg steel torso-like structure. Each headgear model was impacted eight times to the anterior, posterior and sides by a 6.75 kg bowling ball at three heights to produce 52.25, 85 and 144 J 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 (η(2)=0.368). CONCLUSIONS: Taekwondo headgear manufacturers and sport governing bodies must consider improving the design of especially anterior helmet properties.

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 ± 51.67 g) produced a higher RLA than the CA (54.95 ± 20.08 g, 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 ± 1.67 m/s) and that of the JB (4.43 ± 0.78 m/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.