International Physical Medicine & Rehabilitation Journal The kicking process in tae kwon do: a biomechanical analysis; running title: biomechanical analysis of taekwondo Submit Manuscript | http://medcraveonline.com Introduction There are various forms of martial arts practiced throughout the world, each with its own philosophy and style. 1–3 Tae Kwon Do (TKD) is a popular Korean martial art and the most commonly practiced one in the United States. About 2 million people participate in martial arts throughout the United States. 4 When practiced as a light contact sport, TKD is considered relatively safe. 5–7 The increasing interest in TKD is reflected in its recent incorporation into the Olympic Games. 8,9 There are a variety of kicks taught within the sport, which are thought to have different applications and powers. The differences in the biomechanics of the individual kick styles may be accompanied by different injury risks. 10,11 Few studies have rigorously addressed these differences. While some studies have described the types of injuries that take place in TKD, 12,13 the question of how these injuries occur has not been addressed. Most TKD kicking techniques embody high speed and power, and thus present an increased potential for injury. 14 The forces that are generated depend on the kick and how the kick is executed. Some kicks involve stepping towards the target, following a kick. Other kicks involve leaving the ground. Some involve rotation of the pelvis, others involve spinning motions. The kinetics of these separate motions remains unclear. In a study done by Serina et al. 15 the potential incidence of thoracic injury as a result of various TKD kicks was analyzed. A series of four basic kicks were studied including the roundhouse, turning roundhouse, back and sidekicks. The velocity and energy produced by each kick was calculated. They found that the roundhouse and turning- round house kicks are the fastest and they argued that therefore these kicks have the greatest potential for causing soft tissue injury. They also suggested that the back and side kick may predispose a TKD opponent to the highest likelihood of injury given the level of chest compression caused by these kicks. Robertson et al. 16 used a biomechanical model to describe the occurrence of peak power during a front kick. They found that the peak power during a front kick was greater for the open stance than for the closed stance position. They also found that the hip extensors and flexors were the prime movers of both the hip and knee. These studies have however lacked a thorough analysis of the motor strategies employed to deliver a powerful blow. This is important information for TKD proponents who teach this martial art as a means of self defense. In addition, as TKD is becoming an increasingly popular sport, understanding the biomechanics of the various kicks may be used to improve competitiveness and safety within the sport. This may have clinical relevance for the sports medicine physician in that patients may be educated on both how they can improve their strategy and safety during the kicking process. In this study, TKD black belts were recruited to investigate the effectiveness of three types of kicks: the front kick, side kick and round kick completed using two different techniques to deliver the blow. In the first technique, the kicking leg started as the back leg and returned to its original position after the kick was completed. In the second technique, the same back leg was used to kick and then, after completion of the kick, stepped down in the direction of the target. Data was derived using a motion analysis camera-based system and Volume 1 Issue 1 - 2017 David T Burke, 1 Samir al-Adawi, 2 Daniel P Burke, 3 Paolo Bonato, 4 Casey M Leong 5 1 Department of Physical Medicine & Rehabilitation, Harvard Medical School, Spauldin Rehabilitation Hospital, USA 2 Department of Rehabilitation Medicine, Emory University School of Medicine, USA 3 Department of Behavioral Sciences, Sultan Qaboos University, Muscat, Oman 4 The Harvard-MIT Division of Health Sciences and Technology, University of Cambridge, England 5 Georgia College and State University, USA Correspondence: David t Burke, Department of Rehabilitation Medicine & Rehabilitation, Emory University School of Medicine, 1441 Clifton Road Ne, Tel 404-712-5507, Fax 404-712-5895, Email dburke2@emory.edu Received: March 20, 2017 | Published: March 28, 2017 Abstract Objectives: There is a dearth of studies examining the kicks used in Tae Kwon Do (TKD). This study sought to compare the biomechanics of various TKD kicking techniques. Methods: A motion analysis video-camera based system was used to study the biomechanics of three different types of kicks performed by five Black Belt level athletes. The velocity of the kicking foot, the velocity of the pelvis, and the lower body linear momentum were estimated to compare the kicking techniques. Results: Similar patterns of ankle, knee, and hip movement were found for different kicks. The greatest peak foot velocity was observed for the front kick. The peak linear momentum of the lower body was highest for the side kick. Subjects who were able to simultaneously reach peak pelvis velocity and peak lower body linear momentum displayed the best performance. Techniques performed with a step forward after the kicks delivered a more powerful blow than techniques performed by returning to the initial position. Conclusion: This study shows that the fastest kick is the front kick and the most powerful kick is the side kick. The effectiveness of the technique is associated with the coordination of movement of the pelvis and lower body. Keywords: martial arts, biomechanics, tae kwon do, sports injuries Int Phys Med Rehab J. 2017;1(1):8‒13 8 © 2017 Burke et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and build upon your work non-commercially. Research Article Open Access