A critical appreciation of the sport performance determinants of kickboxing from a scientific perspective underpinning its interdisciplinary demands.
Kickboxing is a martial art and sport of attack and defence which originated from a blend of full-contact Karate and Taekwondo mixed with Western Boxing that “uses mathematics of the human body to punch and kick the power system by striking at muscles and nerves” (Reid H et al, 1983, Page 12). Therefore, a combination of Karate and Taekwondo journals, exercise physiology and nutrition text books, and strength and conditioning manuals will be used as sources. The science behind kickboxing consists of a relationship between physiological, psychological, nutritional, biomechanical, technical and medical factors that have significant affects on kickboxing performance.
2.0 Biomechanical determinants and muscular activity breakdown
A fundamental biomechanical attribute of kickboxing is the hooking punch (Figure A) consisting of three phases; drawback, swing and follow through. The performance of the hooking punch relies heavily on flexibility in the shoulders and trunk. By increasing flexibility in these areas, the angular rotation of the swinging punch could be improved by maximising the storage of ‘elastic potential energy’ in both the brachioradialis and tricep muscle that “jump into action the instant it is released” (Palm N, 1997, On-line). This would as a result increase both the momentum and velocity of the fist ensuring maximum impact. Prior to release of the fist, the athlete should press down into the ground with their lead foot so an equal and opposite force helps lift and move the athlete and overcomes the body’s natural reluctance to move (Hamilton N et al, 2002). Good quality leg muscle is essential for this explosive action. As the punch is executed, the elbow follows your fist in a curled position with the biceps and triceps equally contracting and relaxing through their stages of motion. Angular momentum is generated which is a product of the weight of the body and the fist moving in an arc, times the speed of the swing. Furthermore, the closer the arm and fist are to the body, the easier it is to swing. However, more speed is obtained if the fist and arm is swung further away from the body. The ideal position will vary from individual to individual and how far away the opponent is from striking distance. The extensor muscles of the forearm: the extensor pollicis longus, extensor pollicis brevis, abductor pollicis longus and the flexor pollicis longus also contract to pull the wrist back so that it is straight (but not completely locked) and ensures the fist does not buckle on impact. The fist and arm should be tense at point of impact with the front of the first two knuckles (metacarpals) making contact with the opponent or target (See Figure B). Tension is required at the contact stage to counteract any ‘off centre’ punches to the opponents body which creates torque, a measure of how much a force acting on an object causes that object to rotate. Tension during the drawback and swing is counterproductive as it tightens the body slowing down technique.
During the angular motion of the punch, power is also added from the waist. When the shoulder and elbow are drawn back and then pushed forward, the trunk is rotated with ipsilateral contractions of the spinotransversal muscles and contra lateral contractions of the transversospinal muscles, again releasing ‘elastic potential energy’. The ipsilateral obliquus intermus muscle and the contralateral obliquus externus muscle of the abdominal muscle group also contract but to a lesser extent (Palm N, 1997). Additionally, by performing the punch through sequential coordination, generating force from proximal to distal (large muscle groups such as those in the legs and trunk) to distal (small muscle groups such as those in the arms, wrist and hands) the subsequent segments are accelerated at the appropriate time to create the highest possible speed, and maximum force is applied to the final segment (Hamilton N et al, 2002).
Figure A: Lateral view and stages of the lead hooking punch.
Figure B: First two knuckles (metacarpals).
3.0 Physiological functioning
The determination of physiological variables such as heart rate, oxygen consumption, blood lactate and anaerobic threshold through instrumental exercise testing, and relevance to these variables to endurance performance is a major requirement to kick-boxers. Lin and Kuo (2000) (as cited in Lin et al, 2004) found competition in Taekwondo with 3x3 minute rounds with 1 minute break in every fight to increase heart rates up to 165 time/min with some reaching 192 time/min. This implies kickboxing is a high-intensity exercise, which has great impact on circulation and respiratory systems. Melhim (2001) et al (as cited in Lin et al, 2004), found that martial arts exercise could improve cardio respiratory function, improve practitioners’ attack and defense skills, thus enhancing overall performance. In contrast, it was also suggested that male and female contestants with VO2 max of 65ml/kg/min respectively had a better chance to win in competition as they could exercise for longer without fatigue.
In a competitive professional match, kick-boxers must fight a total of 20 minutes. The fight is structured for 10x2 minute rounds with a minute rest interval between each round. An athlete must have an anaerobic threshold level and aerobic power level to meet the demand of this span (Guidetti et al, 2002) (as cited by Lin et al, 2004). Adenosine Triphosphate or ATP, the body’s core “energy currency” as it “powers all forms of biological work” (McArdle W et al, 2001, Page 132) is generated by the anaerobic system to produce fast and powerful punching and kicking combinations, whereas the aerobic system is used to sustain both slower movements such as moving around the ring and progress through the total number of rounds.
The change in blood lactate also has a close relationship with kickboxing intensity and performance. Heller et al (1998) (as cited by Lin et al, 2004) reported that in male and female international martial arts competitions, peak blood lactate after 143 seconds could reach the highest, 11.4 mmol/l which indicates lower blood lactate acid improves intensive training to the player between training and competition period. Furthermore, it was pointed out by Hetzler et al (1989) (as cited by Lin et al, 2004) that martial art athletes with blood lactate ranging from 1.51 to 3.23 mol/100ml, and blood ph value decreasing from 7.39 to 7.34 mg/al, should have the characteristics of very good physical ability, high speed and great strength.
Additionally, the high velocity and explosive nature of martial art movement beneficially teaches the nervous system. Increases in performance are based on neural changes that help individual muscles achieve greater performance capability. By shortening the time of motor unit recruitment, especially fast twitch fibers, and increasing the tolerance of the motor neurons to increased innervations frequencies (Hakkinen, 1986; Hakkinen and Komi, 1983) (as cited by Lin et al, 2004) this is achieved. The initial speed of action and aggressive accelerated movement is a clear determinant of the final outcome of performance, which is why it is important for the coach and player to improve the starting power. Bompa (1999) (as cited by Lin et al, 2004) indicated that the fundamental physiological characteristic necessary for successful performance is the athlete’s ability to recruit the highest possible number of fast twitch fibers to start the motion explosively.
4.0 Nutritional determinants
Professional fighters cut weight and then re-hydrate, trying to put most of their weight back on between weigh-in and competition. This may seem an attractive prospect as the fighter tries to make their weight, however in order to facilitate optimal physiological functioning, the body's water and electrolyte content should remain relatively constant. It has been reported that during prolonged exercise in hot environments, water losses of up to 3 litres per hour, with 90 percent of this total loss occurs through sweating (Coles D, 2005) (as cited by Kesting S, 2005). Dehydration has been shown to remove waste fluids, and reduce blood and plasma volume, decreasing the amount of blood pumped out by the heart, making the heart work harder in an attempt to maintain an adequate oxygenated blood supply to the working muscles (Wilmore and Costill, 1999). Therefore, “high power muscle action in events like boxing and judo is reduced” (Armstrong, 1992, p29).
After completing the weigh-in procedure, fighters rapidly replace lost body fluids in order to return to a normal state of hydration. However, the fighter is unlikely to eat and drink sufficiently because of the negative effects of fighting on a full stomach. Yankanich et al (1998) and Clarkson (1998) stated that the time between the weigh-in and first contest is usually insufficient for fluid and electrolyte balance to be fully re-established in muscles, or for the re-hydration and replenishment of muscle and liver glycogen, thus performance will not be at its optimal level.
Sufficient dietary intake is essential for successful martial arts performance. Carbohydrates high in fiber, vitamins and minerals are the primary source of energy for the body. They act as reserves for vigorous physical activity and are the reason why it has been suggested to refuel with fluid replacement drinks before and between matches (McArdle et al, 2001). During International competition over a week or more, it is important that athletes have recovery meals high in glycemic index to sufficiently re-fuel the depleted carbohydrates and re-synthesize muscle glycogen in time for the following day. When carbohydrate storage is low, protein derived from dietary sources of from muscle breakdown, can be used and is used to some extent as an energy source. Protein is the key to both maintaining energy levels and optimising recovery. The International Olympic Committee suggests protein intakes of about 1.2 – 1.4 grams per kilogram of body weight per day for high endurance athletes. To promote good health and increase exercise performance, lipid intakes should not exceed 30% of the diets energy content, with at least 70% of this from unsaturated fatty acids. With sufficient fat, during strenuous exercise, it is easier to maintain carbohydrate and protein intake to furnish sufficient energy to maintain body weight and muscle mass. (McArdle W et al, 1999).
5.0 Psychological determinants
Psychological interventions such as intrinsic and extrinsic rewards, self-talk, visualization, personality factors and optimal experiences are key methods in enhancing kickboxing performance. The McClelland Atkinson model (1950; 1970’s) states that intrinsic motivation is the same as the motive to achieve success. In other words, people who are intrinsically motivated strive to be competent and self-determining and participate for the love of sport. They enjoy competing at tournaments, like action and excitement and are willing to learn skills to the best of their ability enhancing athletic performance. Conversely, extrinsic motivation implies that performance is controlled by external factors such as medals and trophies, and these forces increase participation and success (Cox H 1998).
Cox H (1998) suggest that self-talk maintains attentional focus and arousal during competition. To accomplish self-talk, the athlete reviews previous events and uses imagery of events in order to have access to their internal processes. Written logs and observations by sport psychologists are used to analyze the self-talk identified. Once the self-talk has been identified, the athlete can analyze it for irrational content by asking a series of questions: “Are they helpful to the athlete? Do they help the athlete reach goals? Do they reduce emotional conflict?.” If the answer to these questions is “no,” the athlete needs to work on modifying the irrational self-talk by firmly and deliberately stopping a thought, changing negative thoughts to more realistic or positive thoughts, countering negative self-statements; and reframing the irrational thoughts to increase performance.
According to Weinberg and Seabourne (1998), through the use of diaphragmatic or focussed breathing, muscle relaxation and body awareness, meditation, and internal experience of movement, optimal performance increases. They conclude that relaxation and imagery together are more effective for martial artists than either alone, martial artists practicing relaxation and imagery ten minutes a day performed better than those who do it immediately before competition, individualized techniques even when taught in a group format are better than standardized group techniques, and individualized cognitive techniques improve performance.
Final performance is also affected by initial training, personality factors: physical, personal, social, identity, and satisfaction in a specific sport. This supports the findings of Duthie et al (1978) who showed that students of martial arts were more self-confident with ‘channels of aggression’ than those without training, and supports the conclusion that "it could be assumed that one or two months of karate training is sufficient to improve the typical student's level of general self-esteem" (Richman & Rehberg, 1986). However, Stephan Kestings’ (2005) research into what makes Rickson Gracie, a “400 pound mind-reading anaconda” and cage fighting veteran, suggests performance is not just about how much or how hard you train or physical personality traits such as strength, speed, toughness, and flexibility, but about how you perceive the environment and how you personally learn from your experience: “ what separates him from his peers in the end, the quality that has led to the very point of the pyramid, is a matter of perception, not so much of what he sees – he does not have exceptional vision – but of how he sees it and how he absorbs it” (Kesting S, 2005, On-line).
Although kickboxing is a specialized area, there is a sufficient research base to conclude that the various sporting determinants discussed can assist martial artists with achieving peak performance in competition. The most important skills to teach in order to enhance performance in kickboxing include, skills training with regular intensity in the martial arts as well as improving the skills to be competitive, suitable dietary for a healthy and fit body; the fitter the athlete, the better their performance will be, and psychological interventions such as visual search strategies and self talk to promote self efficacy and arousal.
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Written by Luke James 2004