Eric D. Zemper1 and Willy Pieter2

 

CEREBRAL CONCUSSIONS IN TAEKWONDO ATHLETES

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REFERENCE: Zemper, E.D., and Pieter, W., "Cerebral Concussion Rates in Taekwondo Athletes," Head and Neck Injuries in Sports, ASTM STP 1229, Earl F. Hoerner, Ed., American Society for Testing and Materials, Philadelphia, 1994.

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1President and Director of Research, Exercise Research Associates of Oregon, P.O. Box 10123, Eugene, OR 97440.

2Research Associate, Exercise Research Associates of Oregon, P.O. Box 10123, Eugene, OR 97440.


ABSTRACT: Injury and exposure data were collected at eight major U.S. taekwondo tournaments between 1988 and 1990, involving 5,682 competitors and a total of 5,566 bouts. There were 802 recorded injuries, 292 (36%) severe enough to cause time-loss of one day or more from further participation. Injuries were equally divided between the head and lower extremities, each accounting for about 40% of the injuries, with the remainder to upper extremities and the body. Cerebral concussions were among the most serious injuries observed, with 58 recorded or approximately 1 for every 100 participants. The total cerebral concussion rate was 5.2/1,000 athlete-exposures or 1.1/1,000 minutes of exposure. These rates of concussions for taekwondo are 3.1 times higher than seen in college football games based on number of exposures, and 7.9 times as high based on time of exposure.

KEYWORDS: cerebral concussion, taekwondo, martial arts, injury rates, epidemiology

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The Korean martial art form of taekwondo was a demonstration sport in the 1988 and 1992 Olympic Games, and it is a candidate to become a medal sport in the future. Despite the increasing popularity and increasing numbers of participants worldwide, little sport science research on taekwondo is currently available. The present study is derived from the injury surveillance phase of an ongoing multi-disciplinary research project on taekwondo athletes initiated by one of the authors (Dr. Willy Pieter), and supported by the U.S. Olympic Committee and the U.S Taekwondo Union. Data reported here were collected at eight major competitions held in the U.S., including the 1988 U.S. Olympic Team Trials, the 1989 and 1990 U.S. Senior National Championships, the 1989 and 1990 U.S. Senior Team Trials, the 1989 and 1990 U.S. Junior National Championships and the 1989 World Junior Championships. These eight tournaments involved a total of 5,682 competitors, including 4,318 males and 1,364 females. There were 4,139 Junior competitors aged 6-17 years old (3,274 males and 865 females) and 1,543 Senior competitors aged 18 years and older (1,044 males and 499 females).

This sport involves kicks and punches to the body and kicks to the head (punches to the head are not allowed). Competitors are categorized into eight weight divisions. Protective equipment includes a chest and rib protector; padding on the forearms, lower legs and dorsal side of the feet; and a light helmet constructed of foam rubber material approximately 1/2 in. thick. Points are scored by well-placed blows to the head and a designated area of the chest and rib protector.

Summaries of results for the general injury patterns found during this study have been reported elsewhere [1-3]. This paper will focus on the occurrence of cerebral concussions during taekwondo competition.

 

METHODS

Injury data were collected with simple check-off forms that describe the athlete and nature, site, circumstances and severity of the injury. These forms are a variation of forms used by the Athletic Injury Monitoring System, a national sports injury data collection system designed and operated by one of the authors (Dr. Eric Zemper). The forms were completed by the authors or by the medical staff covering the competition at the time of treatment for every injury for which treatment was sought by the competitors. All forms were screened on-site by the lead author to ensure completeness and consistency of the completed forms. The classification of cerebral concussion used in this study is that of Nelson et al. [4]. Exposures for calculating injury rates were gathered from records of bouts actually fought. Injury rates are reported as injuries per 1,000 athlete-exposures or per 1,000 minutes of exposure. In this instance, an athlete-exposure is one athlete taking part in one taekwondo bout where he or she is exposed to the possibility of being injured. Since each bout involves two competitors, there are two athlete-exposures per bout. The basic formula for calculating injury rates is: (# of recorded injuries divided by the total number of athlete-exposures) x 1,000 = # injuries per 1,000 athlete-exposures. In the case of injury rates per 1,000 minutes, the total number of athlete-exposures is replaced by the total number of minutes of exposure as the denominator in the equation.

 

RESULTS

In the eight competitions covered during this study the 5,682 participants were involved in 5,566 bouts for a total of 11,132 athlete-exposures (A-E). Accounting for instances where bouts were terminated early because of injury, there were a total of 52,575 min (876.25 h) of exposure. Table 1 summarizes the calculated injury rates for all reported injuries, by gender and level of competition.

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TABLE 1--Total injury rates in taekwondo competition.

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Rate/1,000 A-E

Rate/1,000 min

 

Male

Female

Total

Male

Female

Total

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Juniors

58.2

56.6

57.8

16.1

14.8

15.8

Seniors

93.2

120.7

102.7

13.7

16.1

14.6

TOTALS

67.8

84.9

72.0

15.1

15.6

15.3

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Two types of injury rates are shown in Table 1, rate per 1,000 athlete-exposure and rate per 1,000 min of exposure. Injury rates based on the number of exposures to the possibility of being injured and on the amount of time exposed are much more precise and provide a more accurate picture of injury patterns than the rates per 100 participants most often seen in the literature on sports injuries. There were a total of 802 injuries recorded. For those more familiar with rates per 100 participants, for purposes of comparison, this is equivalent to 14.1 injuries per 100 competitors (13.2/100 competitors for males, 17.1/100 competitors for females, 10.6/100 competitors for Juniors and 23.5/100 competitors for Seniors). The majority of these injuries (64%) were not serious enough to cause termination of participation in the competition. Table 2 summarizes the injury rates for time-loss injuries. Thirty-six percent (292) of the recorded injuries were severe enough to cause time-loss of one day or more from further participation. Twenty-five percent of the injuries to Senior competitors were time-loss injuries, while 45% of the injuries to Juniors involved time-loss. The difference may be explained by physicians being more conservative in recommending a period of non-participation following an injury for children and adolescents than they would be for adult competitors. The total time-loss injury rates of 26.2/1,000 athlete-exposures or 5.6/1,000 min of exposure are equivalent to one time-loss injury in every 10 bouts. These rates are essentially the same for males and females.

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TABLE 2--Time-loss injury rates in taekwondo competition.

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Rate/1,000 A-E

Rate/1,000 min

 

Male

Female

Total

Male

Female

Total

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Juniors

25.7

29.2

26.4

7.1

7.6

7.2

Seniors

27.7

22.2

25.8

4.1

3.0

3.7

TOTALS

26.3

26.1

26.2

5.9

4.8

5.6

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Table 3 shows the distribution of injuries by area of the body. As can be seen, injuries were fairly equally divided between the head and lower extremities, each accounting for about 40% of the injuries, with the remainder occurring in the upper extremities and the body. As might be expected given the nature of this sport, the predominant type of injury was contusions (45%), most of which were not severe enough to cause any time-loss.

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TABLE 3--Distribution of taekwondo injuries by body area.

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# of Time-Loss Injuries

Percent

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Head & Neck

106

36.3

Upper Extremities

35

12.0

Torso

37

12.7

Lower Extremities

114

39.0

TOTALS

292

100.0

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The most common of the more serious injuries observed during the eight tournaments covered in this study were cerebral concussions (Table 4). With 58 such injuries recorded, there was approximately one concussion for every 100 participants. Table 4 presents the cerebral concussion rates by level of competition and gender. They ranged in severity from very mild, involving post-bout headache following a direct blow to the head (Nelson Grade 0), to severe concussions (Nelson Grade 4) involving extended loss of consciousness, retrograde amnesia and, in one case, seizures. There were 11 Grade 0 cerebral concussions recorded, 36 mild concussions of Nelson Grade 1 or 2, 8 moderate or Nelson Grade 3, and 3 severe or Nelson Grade 4. All of the Grade 3 and Grade 4 concussions occurred in males. The total rates for cerebral concussions were 5.2 per 1,000 athlete-exposures or 1.1/1,000 min. of exposure. Males have a somewhat higher rate of concussion than females, while Juniors and Seniors have about the same rate based on athlete-exposures, but Juniors have a higher rate based on minutes of exposure. _________________________________________________________________

TABLE 4--Cerebral concussion rates in taekwondo competition.

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Rate/1,000 A-E

Rate/1,000 min

 

Male

Female

Total

Male

Female

Total

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Juniors

5.4

4.6

5.3

1.5

1.2

1.4

Seniors

6.1

3.3

5.1

0.9

0.4

0.7

TOTALS

5.6

4.0

5.2

1.3

0.7

1.1

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It should be noted in these tables for total injuries, time-loss injuries and concussions that Juniors generally have approximately the same or lower injury rates when calculated based on numbers of athlete-exposures (bouts), but the Juniors have higher rates when based on the number of minutes of exposure. This is due to longer rounds and more rounds per bout for Seniors, resulting in four minutes per bout for Juniors and nine minutes per bout for Seniors. Although the risk of injury per bout is greater for Seniors, the risk of injury per minute of competitive exposure is actually greater for the Juniors.

 

DISCUSSION

A comparison of injury rates in competition for taekwondo and in various intercollegiate sports shows that taekwondo has among the highest time-loss injury rates, exceeded only by football and wrestling [5]. However, when looking specifically at cerebral concussion rates, the situation becomes of more concern. The total concussion rate for collegiate football games is 1.7/1,000 athlete-exposures or 0.14/1,000 min of exposure [6]. College football generally has been considered to have one of the highest concussion rates in American sports, yet the concussion rate for taekwondo competition is 3.1 times higher based on number of athlete-exposures, and 7.9 times that seen in college football games when based on minutes of exposure. This becomes of major concern when considering the cumulative effects of concussion.

It has been shown that memory function and information processing capacity are measurably reduced for up to 30 days after a closed head injury, even those that do not involve loss of consciousness [7,8]. The degree of reduction in function not only is greater in those who have had a previous concussion, but the measurable cognitive deficits also last longer before returning to normal. These closed head injuries (defined as no skull fracture, no intracranial hematoma, no localized neurological signs) have three distinct and measurable effects on memory. First, there is reduction in information processing ability, related to tasks requiring complex processing or tasks with time constraints. Second, there are problems storing material in long-term memory and, third, there is a deficit in retrieval ability once material is stored. This has obvious implications for the classroom performance of school age competitors who sustain even mild head injuries during participation in any sport.

It has been noted that Senior taekwondo athletes can generate velocities of 13-16 m/s during the roundhouse kick, a circular kick most frequently used in competition [9]. The Junior girls who participated in the First Junior Taekwondo World Championships recorded a mean velocity of 12 m/s (range: 9-14.5 m/s) for the roundhouse kick, and the boys 14.7 m/s (range: 12-19.6 m/s). It was estimated that a punch velocity of 8 m/s would result in a peak acceleration of the head of about 200 g, assuming there is no deflection during the punch [10]. Head accelerations of 80 g are hypothesized to cause concussion in adults [11]. It is readily apparent that the velocities generated by even the Junior taekwondo athletes during kicking are more than sufficient to result in cerebral concussion in adults.

Based on the results presented here plus other observations made during this multi-disciplinary study, project staff are working with the U.S. Taekwondo Union Sports Medicine Committee to develop a series of recommendations aimed at reducing risk of cerebral concussion in this sport. These include measures such as requiring the use of mouthguards (currently, use is only recommended, and additional data from this project show that the more severe the concussion the less likely the competitor was wearing a mouthguard); requiring the use in competition of mats to help reduce the possibility of concussion if the head hits the floor during a fall (which was observed on several occasions where competition took place on concrete floors covered only by a thin layer of carpet); and improvements in protective equipment (particularly the helmet). Additional potential rule modifications include adopting a mandatory suspension from participation for a specified period for individuals suffering a knock-out, similar to the rules used in amateur boxing; or disqualification of a competitor who causes a knock-out of an opponent, which would return the emphasis to skill and technique rather than "going for the kill," particularly when behind on points. The two primary areas where this sport may be able to utilize assistance from standard-setting bodies will be in the development of minimum standards for competition mats, and in establishing helmet standards in cooperation with manufacturers to encourage development of headgear with better protective capability.

 

ACKNOWLEDGEMENTS

This study was funded by the U.S. Olympic Committee and supported by the U.S. Taekwondo Union. Thanks also are extended to Samuel Pejo, M.D., Marianette Bailey, R.N., and Charles Bailey for their help in data collection, and to the several attending physicians at the various tournaments for their cooperation.

 

REFERENCES

[1] Zemper, E.D., and Pieter, W., "Injury Rates in Junior and Senior National Taekwondo Competition," in: Proceedings of the First IOC World Congress on Sport Sciences, USOC, Colorado Springs, 1989, pp 219-220.

[2] Zemper, E.D., and Pieter, W., "Injury Rates at the 1988 U.S. Olympic Team Trials for Taekwondo," British Journal of Sports Medicine, Vol. 23, No. 3, 1989, pp 161-164.

[3] Pieter, W., and Zemper, E.D., "The Oregon Taekwondo Project - Part II: Preliminary Injury Research Results," Taekwondo USA, Fall 1990.

[4] Nelson, W.E., Jane, J.A., and Gieck, J.H., " Minor Head Injury in Sports: A New System of Classification and Management," The Physician and Sportsmedicine, Vol. 12, No. 3, 1984, pp 103-107.

[5] McKeag, D., Hough, D., and Zemper, E., Primary Care Sports Medicine, Brown and Benchmark, Dubuque IA, 1993, pp 68-69.

[6] Zemper, E.D., Unpublished data.

[7] Gronwall, D., and Wrightson, P., "Cumulative Effect of Concussion," Lancet, Vol. II(7943), 1975, pp 995-997.

[8] Gronwall, D., and Wrightson, P., " Memory and Information Processing Capacity after Closed Head Injury," Journal of Neurological Surgery and Psychology, Vol. 44, No. 10, 1981, pp 889-895.

[9] Pieter, F., and Pieter, W., "Speed and Force of Selected Taekwondo Techniques," (In Press).

[10] Whiting, W.C., Gregor, K.J., and Finerman, G.A., "Kinematic Analysis of Human Upper Extremity Movements in Boxing," American Journal of Sports Medicine, Vol. 16, No. 2, 1986, pp 130-136.

[11] Smith, P.K., and Hamill, J., "The Effect of Punching Glove Type and Skill Level on Momentum Transfer," Journal of Human Movement Science, Vol. 12, No. 3, 1986, pp 153-161.