Taekwondo USA Fall 1989
USTU-FUNDED SPORTS SCIENCE RESEARCH IN TAEKWONDO
Part I: Overview of the Oregon Taekwondo Project
ERIC D. ZEMPER, Ph.D.
Most of you probably are aware that hardly any scientific research in taekwondo has been done in the West. Some research has been conducted in Korea, but only a few of us have access to or are able to read the results of these studies. If taekwondo is to grow as an Olympic sport, it will need to have its own body of scientific research, just like any other Olympic sport, to help improve the performance of its elite athletes.
In 1987, Willy Pieter, as a new member of the USTU Sports Medicine Committee, started a taekwondo research project that is being funded by the USTU/USOC. The project covers a variety of scientific disciplines and has been conducted through the International Institute for Sport and Human Performance at the University of Oregon in Eugene. Much of the testing, however, takes place at the Olympic Training Center in Colorado Springs with the help of Dr. Jay T. Kearney (Head, Sports Science Division and Sports Physiology Department), Dr. Shane Murphy (Head, Sports Psychology) and Dr. Sarah Smith (Head, Sports Biomechanics) and their respective staffs. Additional data are collected at various national and international tournaments.
This project includes the following research areas:
1. Sports Physiology (including Kinanthropometry);
2. Sports Psychology;
3. Sports Biomechanics;
4. Nutrition; and
5. Epidemiology of Taekwondo Injuries.
Major investigators on the project are Dennis Taaffe (for sports physiology and sports psychology); Eric Zemper, Ph.D. (for epidemiology of taekwondo injuries); and Debra Holloway, B.S. (for nutrition). Project Director is Willy Pieter.
The remainder of this article will give a brief overview of the various components of this research project, which is believed to be the most extensive taekwondo research being conducted in the USA or anywhere else. Articles in future issues of USA Taekwondo will describe in more detail some of the results of this research, and their implications for coaches and athletes.
Some of the measurements taken in this study are used to assess the athlete's body build. Body build is thought to be related to peak performance in sport. For instance, a 7-foot individual most likely is not going to be very successful in gymnastics, while a 6-foot muscular 250-pound person probably will not be an elite marathon runner, but may be more successful in wrestling or judo. Knowing the characteristic body build of an elite athlete in a particular sport will theoretically make it possible to select those individuals who, with the "right" body build, will become champions. Of course, many more factors play a role in making a champion, but body build definitely is one of them. Some of you may know that in Eastern Europe and China potential champions are being selected at an early age (for some sports as early as 5 or 6 years of age) based on their body build.
It is clear why a taekwondo athlete does not want to carry a lot of fat weight. Everybody knows that excess fat generally will inhibit sport performance. The calculation of an athlete's percentage of body fat using skinfold measurements, as is being done in this study, is an estimate of percent body fat. Depending on the sites chosen for the skinfold measurements, the skinfold caliper used and the person doing the measurements, the calculated percent body fat may vary. Other sources of variance are the formula used to calculate percent body fat, racial differences and the climate the athlete is living in. An average measurement error is 3 to 4%. In other words, if the taekwondo athlete's percent body fat has been calculated to be 10%, it actually may be somewhere between 6 and 14%.
Finally, it also should be remembered that everybody has a percentage of so-called essential body fat. This percentage is necessary to stay alive. For women, essential body fat is estimated to be 4% (plus 5% sex-specific fat) and for men it usually is given as 2 - 4%. In other words, 9% of body fat for women is considered to be the minimal level of fat for healthy adult females, whereas 2 - 4% would be the minimal level for men. However, body fat values of 3% or less for men are regarded as underestimates of their percentage body fat. From some of the skinfold measurements and other body measurements that are being taken in this project, the percent body fat of taekwondo athletes is being calculated.
Another physiological factor that is important in taekwondo performance is rather obvious: endurance. Two types of endurance are of importance to the taekwondo athlete: aerobic(with oxygen) and anaerobic (without oxygen) endurance. Aerobic endurance refers to the energy system needed to do work in physical activities while using oxygen over a longer period of time, such as running a 1OK. Anaerobic endurance refers to the energy system needed to do work in physical activities over a shorter period of time (less than 1 minute) without the help of oxygen, such as sprinting a 100m dash. Aerobic endurance is important to taekwondo athletes, because it affects how well they are able to continue performing during the length of a bout and throughout several bouts in a tournament. Anaerobic endurance is important, because it is involved in short bursts of activity, such as in a series of rapid attacks or counterattacks. In this study, aerobic endurance is measured while running for several minutes on a treadmill or cycling on a stationary bike. Anaerobic endurance is measured while pedaling at maximum speed for 30 seconds on a stationary bike.
Limited research is available to compare the aerobic endurance of US taekwondo athletes to elite athletes in other combative sports. This is especially true for females, where there is a void in the research literature on physical and physiological characteristics. Essentially no data are currently available in the research literature on the aerobic endurance of female martial arts athletes and on the anaerobic endurance of both male and female martial arts athletes.
Yet another physiological factor that is important in taekwondo performance is muscle strength. Although most elite athletes in other sports in this country and elsewhere are using strength training to gain a competitive edge, this form of training is still rather unknown in taekwondo. The muscle strength tested in this component of the project involves the same muscle groups used in kicking.
The relative strength or peak torque of the quadriceps and hamstrings during knee extension and flexion is measured on the Cybex machine at four different speeds. The higher speeds of the isokinetic machine with which the strength testing is done in this project more closely resemble actual kicking speeds. The results of the tests we completed on elite taekwondo athletes in 1987 showed that muscle strength during leg extension and flexion, as measured by the Cybex isokinetic machine, was positively related to kicking velocity and force.
In addition to its importance for improved kicking speed, increased muscle strength also will aid in the prevention of injuries. The slower speeds used in the strength evaluation should give an indication of the strength ratio between agonists (muscles which cause the movement to occur) and antagonists (muscles which tend to stop the movement), which is relevant to the potential development of injuries, especially of the hamstrings group. Research on collegiate and professional football players, elite soccer players in the US and other countries, and elite athletes in other sports has shown that increased muscle strength of the hamstrings appeared to prevent the occurrence of injuries to this muscle group. It is well known that the hamstrings are very susceptible to injuries.
Research done on elite taekwondo athletes in Europe, who were competing at the national and international levels, has shown that the hamstrings were injured most during the roundhouse and axe kicks. Without going into any details, the nature of those kicks makes the hamstrings especially vulnerable to injuries if they are too weak. The relative strength of these hamstrings is expressed in the so-called hamstrings to quadriceps ratio, or H/Q ratio. The higher this ratio, the stronger your hamstrings are, and the less likely it is that you will get a hamstrings injury. A suggested value for the H/Q ratio is 60 to 70%; i.e. depending on the speed, the hamstrings should be 60 to 70% as strong as the quadriceps. This ratio will increase with increasing speed, and it also depends on the specific sport. Based on previous research, suggested H/Q values for taekwondo athletes are 70 to 80% at 120º/sec and 90+% at 300º/sec.
Velocity and Force.
This part the taekwondo research project consists of assessing the speed and force with which elite taekwondo athletes kick and punch. Unfortunately, technologically speaking, it is not easy (and even painful at times!) to measure force, as those of you who have already been tested may have noticed. With the equipment available, however, it still is possible to get the general picture of the athlete's speed and force. Why it is important to know the speed and force with which one kicks is obvious, given the nature of this sport. It also is clear why the taekwondo athlete should be able to kick with both the right and left side, regardless of limb dominance. After all, taekwondo competitors could get into a situation during a match where they have to kick with their non-dominant leg. Would it not make sense, then, to know the status of that leg in terms of its speed and force? If there is a deficiency of some sort, the taekwondo athlete or coach can design special exercises to remedy this situation.
In this project, the velocity and force on impact of selected kicks and the reverse punch are measured with a dual-light beam system and a water-filled heavy bag with a built-in force sensor unit. These measurements are relevant to injury prevention and fighting strategy in taekwondo. Being able to bring the non-dominant limb up to par with the dominant limb as much as possible, in terms of speed and force, opens up a whole array of strategic possibilities that can be used during taekwondo fighting. With respect to injuries, the more the taekwondo athlete can alternate kicking with both legs, the less likely the preferred leg will get bruised, for instance.
In this part of the project the men's and women's final matches in each weight division of several team trials and national tournaments are being videotaped in order to get an impression of the specific strategies used by elite male and female taekwondo athletes. Also, it will be possible to study the most frequently used kicks in a competitive setting and the time to complete a kick from the starting position to the moment of impact, In a study of selected matches during the Taekwondo World Championships in 1985, it was found that two of the strategies used were clinching and going out of bounds. Those who eventually won their matches went out of bounds first on an average of 1.1 times per match as opposed to 3.1 times per match for those who eventually lost their matches. It also was found that the winners would initiate attacks rather than counterattack, while the most frequently used kick was the roundhouse kick (ap tollyo ch'agi).
The measurements taken for this part of the project will make it possible to determine which leg is used more often, how attacks are set up, which kicks are used primarily to attack and which ones to counterattack, and so on. More information in this regard should give the coaches a tool in hand to more adequately modify their training programs according to the specific strategies and techniques of successful taekwondo competitors.
Since we are all human beings, we not only function with and through our bodies, but also with and through our minds. For some time now it has been recognized that elite athletes can compete adequately at the national and international levels only if they also train their minds. The Eastern Europeans know this all too well! You may have read in the newspapers or elsewhere that the East Germans and Russians, for instance, are ahead of the US in terms of gold medals won at Olympic Games or world championships of various sports. Eastern European literature shows that a large part of their training is devoted to the psychological training of their elite athletes. Elite athletes of other sports at the OTC in Colorado Springs are working with the available sports psychology facilities and some teams, such as the skiers, gymnasts and figure skaters, have added a sports psychologist to their coaching staff.
In order to assess the mental aspect of elite taekwondo athletes, a number of sport psychological tests are being utilized in this project. As with all sorts of tests, however, they only reflect the situation at one particular moment. In other words, the taekwondo athlete's psychological state at this moment may be entirely different from the time when the tests were taken. It is therefore imperative to retest athletes to get more accurate measurements. In the case of some physiological tests, this may be cumbersome. On the other hand, with most of the psychological tests, this is a lot easier. To assess your anxiety level, for instance, will only take a couple of minutes. In this respect, then, it is more convenient to work with a sport psychologist before and even during competition.
Some of the psychological measurements included in this project are anxiety and mood profiles. To assess the mood profile of the elite taekwondo athlete, the Profile Of Mood States (POMS) is used. The POMS is a scale that measures how the taekwondo athlete is feeling at the time the test is taken. For the elite taekwondo athletes tested in 1987 and 1988, the measures refer to how they were feeling the week before completing the survey. Some of the subscales of the POMS that are used to arrive at the mood profile of the elite taekwondo athlete include depression, vigor, and fatigue.
The depression subscale measures feelings of sadness, guilt and loneliness. Any T-score over 60 indicates a high level of depression and should be a cause for concern. There are many reasons why people get depressed, including the loss of loved ones, personal setbacks and feelings of inadequacy. Continued depression can often be relieved by personal counseling or medication. A (sports) psychologist can be contacted for help in this area.
The subscale of vigor measures feelings of great energy and activity. Athletes generally score higher on this scale than the general population. If an active athlete has a vigor T-score below 50, this may be a warning sign that the athlete feels burnt-out. In such a case, it would probably be a good idea for the athlete to discuss the situation with someone; e.g., the coach or a sports psychologist.
The subscale of fatigue measures a mood weariness, inertia and low energy. For athletes, a high score may be obtained on this scale during periods of intensive or heavy training. This is usually not a problem. However, if fatigue levels are high just prior to important competitions, such as the world championships, this can be a real problem, since intense competition usually requires a great deal of energy. Fatigue levels should be monitored carefully during a training season, as they are good indicators of possible staleness.
It has been found that elite athletes and active people tend to score below the general population mean on the subscales of tension and fatigue, while they score above this mean on vigor. A disturbance in this profile is associated with overtraining, staleness, or being burnt-out, which eventually will result in a decrease in performance. An effective way to prevent this is a reduction in the training load or complete rest.
Research we completed with the 1987 US men's and women's national taekwondo teams revealed, among other things, that two weeks before the 1987 Taekwondo World Championships, the athletes were more depressed and fatigued than their recreational control counterparts. The fact that they were more fatigued is not unexpected after the intensive workouts that they were going through in preparation for the World Championships and in view of their upcoming competition.
Some of you may know that, so far, we have collected injury data during the 1988 Olympic Trials in Colorado Springs and in Raleigh, NC, and during the 1989 US National Taekwondo Championship in Columbus, OH. You should be aware of the importance of knowing more about the types and mechanisms of injuries in your sport, so it is not necessary to explain the relevance of collecting these data. What needs to be stressed, however, is that we only collect reported injuries. From the literature it is known that some 50 - 60% of martial arts injuries incurred at tournaments and during training sessions are not reported. However, at tournaments we generally are able to record all of the most serious injuries, such as fractures and concussions, although we may not see and record all of the more minor injuries, such as bruises, sprains or muscle strains.
The occurrence of injuries is expressed as a rate of injuries per 100 athlete-exposures (A-E). An A-E refers to one athlete participating in a match where he or she is exposed to the possibility of getting injured. In this way, a reasonably accurate account will be possible of the injury rate in taekwondo tournaments, and comparisons can then be made with the occurrence of injuries in other sports. Detailed analysis of the data being collected should also provide clues to ways of preventing or reducing the severity of injuries through changes in equipment, techniques, or possibly changes in rules.
Although nutrition as such will not make a champion, a well balanced diet and knowing when to eat what, and in what quantities, will aid the athlete's preparation to perform up to his or her potential. As in any other weight categorized sport, taekwondo athletes sometimes subject themselves to rather stringent diets in order to lose weight, so that they can compete in a lower weight division. Unfortunately, these practices can be hazardous to the athlete's health and inhibit rather than help taekwondo performance, because much of the weight loss is brought about by loss of muscle mass and dehydration, which can adversely affect the critical electrolyte balance of the body.
Since no information is available at present about the dietary habits of elite taekwondo athletes, this part of the study initially will be concerned with collecting nutritional data from the competitors for the 1989 US Team Trials Finals.
The information from this component of the project will make it possible to give the elite athletes specific advice about their diets. Recommendations also will be made about the athlete's pre-competition meal, what best to eat while the competition is under way, and after it is over.
It is expected that the national coaches will be able to incorporate the information gained from this project into their respective conditioning and training programs, which also may lead to possible adjustments in these programs. It also is expected that selection of potential candidates may become possible through determination of biomechanical, biological and behavioral factors contributing to peak performance in taekwondo, and that training then may be directed to developing this potential.
One should realize, however, that it takes time for results of scientific research to be implemented at the level of the coach or the athlete. This is especially true for taekwondo, because no previous research exists that we can build upon. Of necessity, then, baseline information has to be gathered first before more specific questions of coaches and athletes can be answered. The importance of the present project will therefore become more apparent after a few more years of research. The results will then be more stable and the recommendations based on the research can be made with more confidence.