Kinematic Traits of an Elite Paralympic Karateka: a Case Study

The Journal of Sports Medicine and Physical Fitness EDIZIONI MINERVA MEDICA

Kinematic traits of an elite Paralympic karateka: a case study

Journal: The Journal of Sports Medicine and Physical Fitness Paper code: J Sports Med Phys Fitness-10141 Submission date: July 1, 2019 Article type: Case Report

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EDIZIONI MINERVA MEDICA

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1 Milan, November 22nd, 2019 2 3 Dr. Alberto Oliaro 4 Editor 5 6 The Journal of Sports Medicine and Physical Fitness 7

8 9 Dear Dr. Oliaro, 10 11 12 Please find enclosed the revised version of the manuscript J Sports Med Phys Fitness-10141 13 14 entitled “Kinematic traits of an elite Paralympic karateka: a case study.” 15 16 17 We thoroughly considered all the comments of the Reviewers, and we revised the current 18 19 version of the manuscript. In the following, we provide a description of the changes introduced, 20 which are also highlighted in the manuscript. 21 22 23 24 We would like to thank you and the Reviewers for the time and expertise devoted to 25 improving the quality of our manuscript. I trust that this revised version will be suitable for 26 27 publication in The Journal of Sports Medicine and Physical Fitness. 28

29 30 Best regards, 31 32 33 Chiarella Sforza 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55

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1 2 3 # Reviewer 1 4 R1.1 Major corrections (main criticisms) 5 6 Here are several major concerns: (1) The participant performed a traditional Shotokan 7 8 karate – KATA which is a standardized sequence of karate movements. The some 9 parameters from CoM and knee were analyzed. Those parameters are critical factors to 10 11 KATA? It needs solid evidence-based support. 12 13 We would like to thank the Reviewer for his/her precious suggestions. 14 We thoroughly reconsidered the main passages of the Discussion and Introduction, as 15 16 marked in the text. As suggested, we added in the Introduction a paragraph containing 17 information about the critical factors for Kata performance, that on a biomechanical 18 19 perspective include also those mentioned by the Reviewer. These data are supported by 20 21 previously published studies. 22

23 24 R1.2 (2) Those parameters were analyzed from which karate movement of KATA? which 25 26 movement phase? 27 We agree that the data extraction flow was not clear and we thank the Reviewer for the 28 29 chance to clarify this point. We now added details about the computation of kinematic 30 31 data in the Procedures section. Moreover, we added in the Discussion some features 32 regarding relevant outcomes for knee kinematics in particular step of the sequence. 33 34 35 36 R1.3 (3) Kumite and Kata are two types of karate. The scoring requirements and critical 37 factors are very different between Kumite and Kata. However, some literatures on 38 39 Kumite also cited in the discussion. 40 41 The point raised by the Reviewer is correct. However, the studies we included 42 addressed both kata and kumite athletes (references #2 and #5) in order to highlight 43 44 the relevance of dynamic postural control during the execution karate techniques. In 45 such papers, the importance of the achievement of a adequate technique (also in terms 46 47 of biomechanical parameters) is addressed, and its role in the obtainment of a high-level 48 49 performance is discussed. 50

51 52 # Reviewer 2 53 54 Major corrections (main criticisms) 55

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1 R2.1 The usage of expressions as “reduced” or “decreased” (see detailed comments) are 2 3 inappropriate and should be replaced throughout. However, I feel some speculations on 4 practical consequences or specific recommendations would enhance the value for the 5 6 reader. All the areas where the manuscript needs further improvement have been 7 8 pointed in the specific comments. 9 We would like to thank the Reviewer for his/her precious suggestions. We thoroughly 10 11 checked the manuscript and clarified all the potentially misleading expressions. 12 13 As prompted by this suggestion, we also added some practical outcomes and 14 recommendations that could provide useful insights for the reader. 15 16 17 R2.2 Minor corrections (page, paragraph, line where the author must make the 18 19 corrections) 20 21 Page 2, Line 7: replace “study is” with “study was” 22 Fixed as suggested by the Reviewer. 23 24 25 26 R2.3 Page 2, Line 16: Please delete “traditional”. 27 This word was deleted as suggested by the Reviewer. 28 29 30 31 R2.4 Page 2, Line 16: Please delete “Shotokan” (doubling). 32 Thank you for noticing the typo. We deleted the doubling. 33 34 35 36 R2.5 Page 2, Line 20: replace “more” with “longer” 37 Corrected as suggested by the Reviewer. 38 39 40 41 R2.5 Page 2, Line 22: replace “decreased” with “lower” 42 Corrected as suggested by the Reviewer. 43 44 45 R2.6 Page 2, Line 27: replace “reduced” with “lower” 46 47 Corrected as suggested by the Reviewer. 48 49 50 R2.7 Page 3, Line 9: change “incoming” into “upcoming” 51 52 Changed as suggested by the Reviewer. 53 54 55

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1 R2.8 Page 3, Line 12: change “involving a sequence” into “involving sequences” 2 3 Changed as suggested by the Reviewer. 4 5 6 R2.9 Page 3, Lines 28-30: This is also true for the non-paralympic games, I guess. 7 8 The point raised by the Reviewer is correct. We focused only on the Paralympic Program 9 to highlight the lack of international recognition for top level competitions of para- 10 11 karate. However, if the Reviewer believes that adding a reference to able-bodied 12 13 competitions should clarify the context for the reader, we are open to add more details. 14 15 16 R2.10 Page 3, Line 53: change “Participants” into “Participant” 17 We made the change as suggested by the Reviewer. 18 19 20 21 R2.11 Page 4, Lines 14-16: What does “5/6” or “3/4” mean in this context? 22 The Paralympic karateka trained 5 to 6 times per week before and 3 to 4 times per week 23 24 after the operations. We agreed that there was a lack of clarity. We clarified this 25 26 sentence by replacing “/” with “to”. 27 28 29 R2.12 Page 4, Line 29: Which kata was performed? 30 31 As stated, the kata was the same of the previous study (reference #14) taken as a 32 comparison with able-bodied athletes. We intentionally didn’t report the entire 33 34 sequence of movements to avoid redundancy. However, if the Reviewer believes that 35 36 adding the description of the whole sequence of movement should be useful for the 37 reader, we are available to add the details of kata performed. 38 39 40 41 R2.13 Page 4, Line 37: What does “advancement” means? “in front”? “forwards”? 42 We acknowledge that passage was not as clear as we intended. We added “forward” 43 44 before “advancement” to clarify the direction of the movement. 45

46 47 R2.14 Page 5, Line 43: replace “reduced” with “lower” 48 49 Replaced as suggested by the Reviewer. 50

51 52 R2.15 Page 6, Line 29: replace “decreased” with “was lower” 53 54 Replaced as suggested by the Reviewer. 55

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1 2 3 R2.16 Page 7, Line 13: What does “decreasing” mean in this context? 4 Thanks for the question. We replaced “decreasing” with a more consistent expression to 5 6 highlight physical impairments negative effects. 7 8 9 R2.17 Page 9, Lines 19-21: Please correct citation #5. 10 11 Thanks for noticing the error. We corrected the citation adding the missing details. 12 13 14 R2.18 Figures 1 and 2: The resolution of the figures should be improved. Why did you 15 16 report the median instead of the mean with 95% confidence intervals? 17 We now exported the figures at higher resolution. 18 19 Thanks for noticing the typo. We replaced “median” with “mean”. 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55

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1 Kinematic traits of an elite Paralympic karateka: a case study 2 3 4 Authors: Filippo BERTOZZI1#, Matteo ZAGO1,2#, Daniela CIPRANDI1, Christel GALVANI3, 5 6 Chiarella SFORZA1,4* 7

8 9 Authors affiliations: 1Department of Biomedical Sciences for Health, Università degli Studi di 10 2 11 Milano, Milan, Italy; Department of Electronics, Information and Bioengineering (DEIB), 12 Politecnico di Milano, Milan, Italy; 3Department of Psychology, Università Cattolica del Sacro 13 14 Cuore, Milan, Italy; 4Institute of Molecular Bioimaging and Physiology, National Research 15 16 Council, Segrate, Italy 17 #Dr Bertozzi and Dr Zago equally contributed to this study 18

19 20 *Corresponding author: 21 22 Prof. Chiarella Sforza, MD 23 24 Dipartimento di Scienze Biomediche per la Salute, Università degli Studi di Milano 25 Via Mangiagalli 31, 20133, Milan, Italy 26 27 [email protected] 28

29 30 Abstract word count: 215 31 32 Text-only word count: 1920 33 Number of figures and tables: 2 figures; 1 table 34 35 Number of references: 26 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55

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1 ABSTRACT 2 3 Karate is a martial art that include striking, kicking and punching techniques, demanding and 4 requires high levels of functional abilities skills. Karate counts millions of practitioners 5 6 worldwide and it is also spreading in Paralympic competitions, requiring: there is a need for 7 accurate categories definition for disabled athletes. The aim of the present current study is was 8 9 to present kinematic data of an elite Paralympic karateka, in comparison with able-bodied 10 11 athletes, to promote a better classification within the discipline, based on objective evaluations 12 of physical impairments. A male black belt Paralympic karateka (age: 36 years; body weight: 13 14 75.5 kg; height: 173 cm) with lower limbs impairments was evaluated. He performed a 15 16 standardized sequence of movements (kata) from traditional Shotokan karate Shotokan. Joints 17 and center-of-mass kinematics were collected with an optoelectronic motion capture system 18 19 and compared with those obtained in two groups of able-bodied (Masters and Practitioners) 20 athletes from a previous study. The sequence performed by the karateka lasted more longer 21 22 than in both able-bodied groups. Center of mass velocity and acceleration decreased lowered 23 24 in comparison with Masters. Knees range of movement and peak angular velocity were similar 25 to Practitioners but lower than Masters. We concluded that The physical impairments 26 27 negatively affected the function of lower limbs in the Paralympic athlete, as fundamental skills 28 in karate elite performance (dynamic balance control and joint angular velocity) were reduced 29 30 lower. 31 32 Keywords: martial arts, adapted physical activity, sport biomechanics, disability, motion 33 capture. 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55

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1 INTRODUCTION 2 3 Karate is a Japanese martial art that originated in the island of Okinawa and spread worldwide 4 following World War II. Nowadays the World Karate Federation (WKF) claims that Karate has 5 6 more than 100 million practitioners in 194 national federations around the world. Moreover, 7 the International Olympic Committee (IOC) has recently included karate competitions as an 8 9 additional sport in the incoming upcoming Tokyo 2020 Olympic Games program. 10 11 Karate competition consists of kumite, competitive sparring, and kata, an exhibition of forms 12 involving a sequence sequences of offensive and defensive movements targeting a virtual 13 14 opponent1. These movements include mainly striking, kicking and punching techniques and 15 2 16 require high levels of functional and motor abilities . During a conventional fight system, 17 conducted within a sustained endurance regimen, the karateka highly increase their ventilation 18 3 19 and blood pressure . Furthermore, continuative karate training improves physical qualities 20 including flexibility, strength, balance and cardiorespiratory fitness4–7. 21 22 Recently, consideration for adapted physical activity (APA) for people with physical or 23 24 cognitive impairments increased, alongside with the inclusion of Paralympic disciplines in 25 national sport federations. In addition, some studies regarding elite Paralympic athletes have 26 27 been published 8–12. 28 To date, among oriental martial arts, only Judo and Taekwondo entered the Paralympic Games 29 30 program. However, WKF has been working since 2006 to create para-karate, with competitions 31 32 involving athletes with various disabilities. In 2015 WKF has also been recognized as a member 33 by the International Paralympic Committee. 34 35 Biomechanical analyses can highlight the residual functional ability of athletes and provide an 36 37 evidence-based classification in Paralympic sports, showing how physical impairments 38 influence activity and sport performance13. One of the main factor affecting performance in 39 40 kata competition is dynamic postural control, represented by the kinematic analysis of the body 41 Center of Mass (CoM)2,5,14,15. Information about CoM displacement, velocity and acceleration 42 43 during Karate techniques execution offer a general description of whole-body movements and 44 1,15–17 45 reflects athletes’ ability and experience . 46 Moreover, some studies identified knee movements as crucial factors for enhancing 47 48 performance in both punching and kicking kata techniques18–21. 49 However Despite the determinants of kata performance were extensively discussed in the actual 50 51 body of literature, no studies currently reported data regarding the biomechanics of Paralympic 52 13,14 53 karate. In fact, some studies reported differences between elite athletes and practitioners , 54 55

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1 but to date no one has presented a comparison between high level Paralympic and able-bodied 2 3 karateka. 4 Therefore, the purpose of this study was to evaluate body kinematics of an elite Paralympic 5 6 karateka (national champion), comparing his data to those collected in a previous study 7 conducted on able-bodied karateka15. 8 9 The findings of this work could be useful both for karate coaches and physical therapists in 10 11 improving their training and rehabilitation strategies for Paralympic athletes. 12 13 14 CASE REPORT 15 16 Participants 17 Kinematic assessment was accomplished on a 36-year-old male black belt Paralympic karateka 18 19 (body weight: 75.5 kg; height: 173 cm). He was a member of Federazione Italiana Judo Lotta 20 Karate Arti Marziali (FIJLKAM, affiliated to WKF) and national champion of para-karate 21 22 individual kata. Furthermore, he took part in several international competitions of para-karate. 23 24 His physical disability was caused by complications after surgical operations, due to tendons 25 laxity in his lower limbs. At the moment of evaluation, the main impairment was a complete 26 27 bilateral gastrocnemius and soleus atrophy, that caused a notable decrease in knee and ankle 28 mobility and force output. The athlete had been performing high level karate for 20 years before 29 30 the disability took place, with 5/ to 6 training sessions per week. After the post-operative 31 32 rehabilitation, he attended 3/ to 4 sessions of para-karate training per week. 33 The karateka signed an informed written consent; the study was approved by the local Ethics 34 35 committee and met the current ethical standards in sports and exercise research, according to 36 37 Helsinki Declaration. 38 Kinematic parameters were compared to those from obtained in a previous study investigation, 39 40 conducted with analogous procedures on 10 able-bodied black belt karateka divided in two 41 groups: Masters (elite karateka, members of the Italian national team), and Practitioners (non- 42 43 elite, amateurs karateka)1,15. 44 45 Procedures 46 The karateka performed seven repetition of the same kata performed in of the previous 47 48 study, defined by an experienced Master of Shotokan karate, to allow a comparison with able- 49 bodied athletes. In short, movements composing the sequence of 11 steps were chosen among 50 51 the fundamental techniques of traditional Shotokan karate15. Before trials, the karateka warmed 52 53 up with his coach. The sequence was performed at maximum effort; between repetitions, full 54 recovery was conceded. 55

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1 The 11-steps sequence was performed along three directions (forward advancement, right 2 3 backward displacement and left advancement) and included advancement and backward 4 positions, blocks, punches, and a circular kick with the left leg. 5 6 Twenty-three body markers (diameter: 15 mm) were placed on the skin at the following 7 landmarks: right and left tragion, acromion, olecranon, radius styloid process, anterosuperior 8 9 iliac spines, great trochanter, femoral lateral epicondyle, lateral malleolus, heel, toe, glabella, 10 th 11 spinous process of the 7 cervical vertebra, sacrum. The three-dimensional coordinates of each 12 landmark were recorded at 120 Hz by an optoelectronic motion capture system (BTS Smart-E, 13 14 Milano, Italy). The markers coordinates were filtered with a 15 Hz, low-pass, 2nd order 15 16 Butterworth filter. The 11 events linked defining the timing of to each kata technique were 17 manually located using the motion capture software. Sequence duration was calculated between 18 19 the first and the last event. 20 Knee flexion angles were computed under the simplifying assumption of 1-degree-of-freedom 21 22 joints. Angular range of motion (RoM) during the sequence and peak angular velocity were 23 24 obtained to provide a complete joints motion description. 25 body Center of Mass () CoM coordinates were estimated using the Segmental Centroid 26 27 Method23. CoM height and vertical displacement were computed as the mean of the values over 28 29 the entire kata and normalized to the body height. Horizontal displacement was expressed as 30 the sum of all movements of the CoM projection on the horizontal plane. CoM average velocity 31 32 was calculated over the whole sequence, as well as CoM acceleration, expressed by the root 33 mean square (rms) of the relative track. 34 35 Statistical analysis 36 37 Each kinematic parameter regarding the Paralympic karateka was expressed as the mean over 38 trials. Kinematic variables for Masters and Practitioners were presented as group mean together 39 40 with 95% confidence intervals (CI). To assess differences between Paralympic karateka and 41 able-bodied groups, the one-sample t-tests were performed. The Significance level was set at 42 43 5% (p<0.05). 44 45 46 RESULTS 47 48 The duration of the kata sequence performed by the karateka was significantly longer than those 49 50 of both Masters and Practitioners (6.51 s vs. 3.33 s, p<0.001 and 3.96 s, p=0.012 respectively). 51 Table 1 lists CoM and knee kinematics data of Paralympic karateka compared with able-bodied 52 53 groups. 54 55

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1 Table 1 2 3 4 Figures 1 and 2 show CoM and knee kinematics results. Masters and Practitioners data are 5 6 displayed as percentage increment or decrement from the Paralympic karateka mean values, 7 taken as reference, together with 95% CIs. 8 9 When compared to elite karateka, CoM average velocity was 73% lower (p<0.001) and 10 11 acceleration was 21% lower (p=0.053). Additionally, knee RoM and peak angular velocity were 12 significantly reduced lower, except for right knee RoM. 13 14 15 16 Fig. 1 – Fig. 2 17 18 19 DISCUSSION 20 To date very few researches have been conducted on the biomechanical profile of Paralympic 21 22 athletes13, and none reported quantitative biomechanical data concerning martial arts, despite 23 24 their global spread. To partially fill this gap, in our study we evaluated an elite Paralympic 25 karateka, with serious lower limb impairments, was evaluated and we compared his kinematics 26 27 was compared features with those of able-bodied athletes. 28 CoM kinematics 29 30 In kata, likewise the correct execution of techniques, balance control represents the main 31 2,5,15 32 performance factor for athletes’ evaluation . The karateka’s dynamic balance should be 33 maintained during constant and rapid movements. 34 35 Dynamic balance has been demonstrated to be strongly related with CoM position and 36 24 37 displacement . In Paralympic karateka, lower limb impairments could influence CoM 38 displacement, velocity and acceleration, affecting the whole-body postural control. 39 40 The current study revealed that the duration of the sequence performed by the karateka was 41 considerably longer than that of healthy Masters and Practitioners. We can hypothesize that a 42 43 complex sequence of movement, such as the selected kata, requires more time to be executed 44 45 by a disabled athlete. Indeed, lower limb impairments can modify patterns of movement and 46 decrease the velocity of displacements, consequently increasing the time required to perform 47 48 the whole sequence. 49 CoM height and vertical displacement were similar to those of elite athletes: the karateka 50 51 preserved his ability to control static balance adjustments. On the other hand, CoM average 52 53 velocity and acceleration decreased were lower. Since the angular acceleration is theoretically 54 proportional to the resultant torque power at the joint, this trait is probably the consequence of 55

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1 the powerlessness inability of calf muscular area to express normal moments of force levels of 2 3 power. Therefore, dynamic balance together with the ability of moving the CoM in space with 4 a high-power rate could be negatively affected. 5 6 Knee kinematics 7 In karate, techniques are performed much faster than in any other martial arts3, requiring high 8 9 levels of speed and agility2. A high grade of muscular power is needed during kicking actions. 10 11 Moreover, elevate joints angular velocities during these movements are essential features for 12 elite karateka25. 13 14 Considering that the knee was the joint mainly affected by the disability, notable differences 15 16 were expected. RoM values for both knees were similar between the Paralympic karateka and 17 Practitioners, also taking the great variability of amateurs’ parameters into account. Comparing 18 19 the same parameters with Masters’, a decrease of 12% for both knees occurred. In particular, 20 considering step 4, a transitional phase from a forward punch to a blocking technique using the 21 22 left limb as a single support, the right knee was considerably less flexed than both in 23 24 Practitioners and Amateurs. Since the karateka executed the movement during a unipedal 25 stance, it should be reasonable that the knee of the swinging leg was less flexed to maintain the 26 27 right foot closer to the base of support. This could be a strategy to oppose the loss of control 28 during the single limb stance, probably due to the weakness of the support leg. 29 30 Analyzing Concerning the peak angular velocity, we can notice the same behavior of RoMs. 31 32 Besides a high variability, the Paralympic karateka had quite similar results compared to 33 Practitioners, while he showed a clear reduction of his physical performance when a 34 35 comparison with Masters was done. Bearing in mind the similar exposure to practice (20 vs. 17 36 15 37 years) , we can state that the strong reduction of calf muscular tissue had negatively affected 38 the performance, entailing reduction of RoMs and slowness of knee movements. 39 18–21 40 Knee kinematics is crucial in high level kata punching and kicking techniques . Thus, a 41 recommended purpose for physical therapists and karate coaches, working with Paralympic 42 43 athletes, should be to recover, as much as possible, acceptable levels of strength and RoM at 44 45 the joint. Exercises improving joint mobility, during rehabilitation phase and practices, should 46 allow to increase knee flexion and thus maintain CoM lower during movements, enhancing 47 48 dynamic balance. Moreover, trainers should aim to retrieve leg extensors muscular strength, 49 preserving at the same time a normal hamstrings-to-quadriceps ratio to avoid injuries and 50 51 asymmetries26. 52 53 The study has some limitations. Firstly, the peculiarity of the athlete’s physical impairments 54 has not allowed a collection of data on a larger sample. Moreover, we didn’t measure muscular 55

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1 force output or muscular activation. Finally, to compare the karateka’s values with data from 2 3 the previous study, some joints were excluded from kinematic computations. 4 5 6 CONCLUSION 7 In this study, whole body kinematics of a Paralympic elite karateka was analyzed and compared 8 9 to the same parameters of able-bodied athletes. The physical impairments of the assessed athlete 10 11 negatively affected his of lower limbs function in the karateka, decreasing negatively altering 12 key factors for kata performance, like dynamic balance control and knee joints RoMs and 13 14 angular velocity. 15 16 Since Paralympic categorization for karate is already in process, this case report could support 17 a better classification and encourage further biomechanical studies on disabled athletes. 18 19 20 NOTES 21 22 23 24 Acknowledgements 25 The authors warmly thank Alessio Castellano for his participation and Mauro Frustagli for his 26 27 precious suggestions. 28

29 30 Disclosure 31 32 The authors have no conflicts of interest to declare. 33 34 35 Authors’ contributions 36 37 All authors meet the criteria for authorship established by the International Committee of 38 Medical Journal Editors. 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55

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1 REFERENCES 2 3 4 1. Zago M, Codari M, Iaia FM, et al. Multi-segmental movements as a function of 5 6 experience in karate. J Sports Sci 2017; 35: 1515–1522. 7 2. Filingeri D, Bianco A, Zangla D, et al. Is karate effective in improving postural 8 9 control? Arch Budo 2012; 8: 203–206. 10 11 3. Arus E. Biomechanics of Human Motion: Applications in the Martial Arts: Second 12 Edition. 2nd Editio. Boca Raton, Florida: CRC Press, Taylor & Francis. Epub ahead of 13 14 print 9 November 2017. DOI: 10.1201/b22446. 15 16 4. Violan MA, Small EW, Zetaruk MN, et al. The Effect of Karate Training on 17 Flexibility, Muscle Strength, and Balance in 8- to 13-Year-Old Boys. Pediatr Exerc Sci 18 19 1997; 9: 55–64. 20 5. Gauchard GC, Lion A, Bento L, et al. Postural control in high-level kata and kumite 21 22 karatekas. Mov Sport Sci - Sci Mot 2018; 100: 21–26. 23 24 6. Origua Rios S, Marks J, Estevan I, et al. Health benefits of hard martial arts in adults: a 25 systematic review. J Sports Sci 2018; 36: 1614–1622. 26 27 7. Mastnak W. Karate-based prevention of work-related musculoskeletal syndromes: a 28 study on the possible benefits of martial arts in sports medicine and for occupational 29 30 health. Sport Sci Health 2017; 13: 1–8. 31 32 8. Brickley G, Gregson HC. A Case Study of a Paralympic Cerebral Palsy Cyclist Using 33 Torque Analysis. Int J Sports Sci Coach 2011; 6: 269–272. 34 35 9. Boyd C, Barnes C, Eaves SJ, et al. A time-motion analysis of Paralympic football for 36 37 athletes with cerebral palsy. Int J Sports Sci Coach 2016; 11: 552–558. 38 10. Bednarczuk G, Molik B, Morgulec-Adamowicz N, et al. Static balance of visually 39 40 impaired paralympic goalball players. Int J Sports Sci Coach 2017; 12: 611–617. 41 11. Cavaggioni L, Trecroci A, Tosin M, et al. Individualized dry-land intervention program 42 43 for an elite Paralympic swimmer. J Sports Med Phys Fitness 2018; 59: 82–86. 44 45 12. Mashkovskiy E, Magomedova A, Achkasov E. Degree of vision impairment influence 46 the fight outcomes in the Paralympic judo: a 10-year retrospective analysis. J Sports 47 48 Med Phys Fitness 2019; 59: 376–379. 49 13. Morriën F, Taylor MJD, Hettinga FJ. Biomechanics in Paralympics: Implications for 50 51 Performance. Int J Sports Physiol Perform 2017; 12: 578–589. 52 53 14. Cesari P, Bertucco M. Coupling between punch efficacy and body stability for elite 54 karate. J Sci Med Sport 2008; 11: 353–356. 55

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TABLES

1 Table2 1: Paralympic Karateka kinematic values (meanSD) and statistical significance (one-sample t-test) of differences with able-bodied groups 3 p p 4 CoM kinematics Knee kinematics 5 Masters Practitioners Masters Practitioners 6

CoM7 height (% of body 47.13  3.54 0.877 0.007 Right knee RoM (rad) 1.41  0.08 0.075 0.259 height)8 9 CoM horizontal 10 2.96  0.10 0.009 0.004 Left knee RoM (rad) 1.81  0.13 0.003 0.250 11displacement (m) 12 CoM vertical displacement Right knee peak angular 13 13.45  0.76 0.489 0.355 10.14  0.64 0.027 0.864 (% of body height) velocity (rad/s) 14 15CoM average velocity (m/s) <0.001 0.495 0.44  0.08 Left knee peak angular 16 16.12  1.98 0.005 0.303 velocity (rad/s) 17CoM rms acceleration (m/s) 3.63  0.53 0.053 0.053 18 19 20 21 22 23 24 25 26 27

29 30 31 32 33 34 Abbreviations:35 CoM, center of mass; RoM, range of motion; rms, root mean square 36 37 38

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1 TITLES OF FIGURES 2 3 4 Figure 1 Median Mean of Masters (circles) and Practitioners (squares) and 95% Confidence Intervals 5 6 (bars) relative to the percentage change of CoM kinematic variables, taking the Paralympic karateka 7 values as reference (0%). Negative values express a decrease while positive values express an 8 9 increase, compared to Paralympic karateka values 10 11 12 Figure 2 Median Mean of Masters (circles) and Practitioners (squares) and 95% Confidence Intervals 13 14 (bars) relative to the percentage change of knee kinematic variables, taking the Paralympic karateka 15 16 values as reference (0%). Negative values express a decrease while positive values express an 17 increase, compared to Paralympic karateka values 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55

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1 Kinematic traits of an elite Paralympic karateka: a case study 2 3 4 Authors: Filippo BERTOZZI1#, Matteo ZAGO1,2#, Daniela CIPRANDI1, Christel GALVANI3, 5 6 Chiarella SFORZA1,4* 7

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1 ABSTRACT 2 3 Karate is a martial art that include striking, kicking and punching techniques, and requires high 4 levels of functional skills. Karate counts millions of practitioners worldwide and it is also 5 6 spreading in Paralympic competitions: there is a need for accurate categories definition for 7 disabled athletes. The aim of the current study was to present kinematic data of an elite 8 9 Paralympic karateka, in comparison with able-bodied athletes, to promote a better classification 10 11 within the discipline, based on objective evaluations of physical impairments. A male black 12 belt Paralympic karateka (age: 36 years; body weight: 75.5 kg; height: 173 cm) with lower 13 14 limbs impairments was evaluated. He performed a standardized sequence of movements (kata) 15 16 from Shotokan karate. Joints and center-of-mass kinematics were collected with an 17 optoelectronic motion capture system and compared with those obtained in two groups of able- 18 19 bodied (Masters and Practitioners) athletes from a previous study. The sequence performed by 20 the karateka lasted longer than in both able-bodied groups. Center of mass velocity and 21 22 acceleration lowered in comparison with Masters. Knees range of movement and peak angular 23 24 velocity were similar to Practitioners but lower than Masters. We concluded that physical 25 impairments negatively affected the function of lower limbs in the Paralympic athlete, as 26 27 fundamental skills in karate elite performance (dynamic balance control and joint angular 28 velocity) were lower. 29 30 31 32 Keywords: martial arts, adapted physical activity, sport biomechanics, disability, motion 33 capture. 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55

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1 INTRODUCTION 2 3 Karate is a Japanese martial art that originated in the island of Okinawa and spread worldwide 4 following World War II. Nowadays the World Karate Federation (WKF) claims that Karate has 5 6 more than 100 million practitioners in 194 national federations around the world. Moreover, 7 the International Olympic Committee (IOC) has recently included karate competitions as an 8 9 additional sport in the upcoming Tokyo 2020 Olympic Games program. 10 11 Karate competition consists of kumite, competitive sparring, and kata, an exhibition of forms 12 involving sequences of offensive and defensive movements targeting a virtual opponent1. These 13 14 movements include mainly striking, kicking and punching techniques and require high levels 15 2 16 of functional and motor abilities . During a conventional fight system, conducted within a 17 sustained endurance regimen, the karateka highly increase their ventilation and blood pressure3. 18 19 Furthermore, continuative karate training improves physical qualities including flexibility, 20 strength, balance and cardiorespiratory fitness4–7. 21 22 Recently, consideration for adapted physical activity (APA) for people with physical or 23 24 cognitive impairments increased, alongside with the inclusion of Paralympic disciplines in 25 national sport federations. In addition, some studies regarding elite Paralympic athletes have 26 27 been published 8–12. 28 To date, among oriental martial arts, only Judo and Taekwondo entered the Paralympic Games 29 30 program. However, WKF has been working since 2006 to create para-karate, with competitions 31 32 involving athletes with various disabilities. In 2015 WKF has also been recognized as a member 33 by the International Paralympic Committee. 34 35 Biomechanical analyses can highlight the residual functional ability of athletes and provide an 36 37 evidence-based classification in Paralympic sports, showing how physical impairments 38 influence activity and sport performance13. One of the main factor affecting performance in 39 40 kata competition is dynamic postural control, represented by the kinematic analysis of the body 41 Center of Mass (CoM)2,5,14,15. Information about CoM displacement, velocity and acceleration 42 43 during Karate techniques execution offer a general description of whole-body movements and 44 1,15–17 45 reflects athletes’ ability and experience . 46 Moreover, some studies identified knee movements as crucial factors for enhancing 47 48 performance in both punching and kicking kata techniques18–21. 49 Despite the determinants of kata performance were extensively discussed in the actual body of 50 51 literature, no studies currently reported data regarding the biomechanics of Paralympic karate. 52 13,14 53 In fact, some studies reported differences between elite athletes and practitioners , but to 54 55

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1 date no one has presented a comparison between high level Paralympic and able-bodied 2 3 karateka. 4 Therefore, the purpose of this study was to evaluate body kinematics of an elite Paralympic 5 6 karateka (national champion), comparing his data to those collected in a previous study 7 conducted on able-bodied karateka15. 8 9 The findings of this work could be useful both for karate coaches and physical therapists in 10 11 improving their training and rehabilitation strategies for Paralympic athletes. 12 13 14 CASE REPORT 15 16 Participant 17 Kinematic assessment was accomplished on a 36-year-old male black belt Paralympic karateka 18 19 (body weight: 75.5 kg; height: 173 cm). He was a member of Federazione Italiana Judo Lotta 20 Karate Arti Marziali (FIJLKAM, affiliated to WKF) and national champion of para-karate 21 22 individual kata. Furthermore, he took part in several international competitions of para-karate. 23 24 His physical disability was caused by complications after surgical operations, due to tendons 25 laxity in his lower limbs. At the moment of evaluation, the main impairment was a complete 26 27 bilateral gastrocnemius and soleus atrophy, that caused a notable decrease in knee and ankle 28 mobility and force output. The athlete had been performing high level karate for 20 years before 29 30 the disability took place, with 5/ to 6 training sessions per week. After the post-operative 31 32 rehabilitation, he attended 3/ to 4 sessions of para-karate training per week. 33 The karateka signed an informed written consent; the study was approved by the local Ethics 34 35 committee and met the current ethical standards in sports and exercise research, according to 36 37 Helsinki Declaration. 38 Kinematic parameters were compared to those obtained in a previous investigation, conducted 39 40 with analogous procedures on 10 able-bodied black belt karateka divided in two groups: 41 Masters (elite karateka, members of the Italian national team), and Practitioners (non-elite, 42 43 amateurs karateka)1,15. 44 45 Procedures 46 The karateka performed seven repetition of the same kata performed in the previous 47 48 study, defined by an experienced Master of Shotokan karate, to allow a comparison with able- 49 bodied athletes. In short, movements composing the sequence of 11 steps were chosen among 50 51 the fundamental techniques of traditional Shotokan karate15. Before trials, the karateka warmed 52 53 up with his coach. The sequence was performed at maximum effort; between repetitions, full 54 recovery was conceded. 55

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1 The 11-steps sequence was performed along three directions (forward advancement, right 2 3 backward displacement and left advancement) and included advancement and backward 4 positions, blocks, punches, and a circular kick with the left leg. 5 6 Twenty-three body markers (diameter: 15 mm) were placed on the skin at the following 7 landmarks: right and left tragion, acromion, olecranon, radius styloid process, anterosuperior 8 9 iliac spines, great trochanter, femoral lateral epicondyle, lateral malleolus, heel, toe, glabella, 10 th 11 spinous process of the 7 cervical vertebra, sacrum. The three-dimensional coordinates of each 12 landmark were recorded at 120 Hz by an optoelectronic motion capture system (BTS Smart-E, 13 14 Milano, Italy). The markers coordinates were filtered with a 15 Hz, low-pass, 2nd order 15 16 Butterworth filter. The 11 events defining the timing of to each kata technique were manually 17 located using the motion capture software. Sequence duration was calculated between the first 18 19 and the last event. 20 Knee flexion angles were computed under the simplifying assumption of 1-degree-of-freedom 21 22 joints. Angular range of motion (RoM) during the sequence and peak angular velocity were 23 24 obtained to provide a complete joints motion description. 25 CoM coordinates were estimated using the Segmental Centroid Method23. CoM height and 26 27 vertical displacement were computed as the mean of the values over the entire kata and 28 29 normalized to the body height. Horizontal displacement was expressed as the sum of all 30 movements of the CoM projection on the horizontal plane. CoM average velocity was 31 32 calculated over the whole sequence, as well as CoM acceleration, expressed by the root mean 33 square (rms) of the relative track. 34 35 Statistical analysis 36 37 Each kinematic parameter regarding the Paralympic karateka was expressed as the mean over 38 trials. Kinematic variables for Masters and Practitioners were presented as group mean together 39 40 with 95% confidence intervals (CI). To assess differences between Paralympic karateka and 41 able-bodied groups, the one-sample t-tests were performed. Significance level was set at 5% 42 43 (p<0.05). 44 45 46 RESULTS 47 48 The duration of the kata sequence performed by the karateka was significantly longer than those 49 50 of both Masters and Practitioners (6.51 s vs. 3.33 s, p<0.001 and 3.96 s, p=0.012 respectively). 51 Table 1 lists CoM and knee kinematics of Paralympic karateka compared with able-bodied 52 53 groups. 54 55

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1 Table 1 2 3 4 Figures 1 and 2 show CoM and knee kinematics results. Masters and Practitioners data are 5 6 displayed as percentage increment or decrement from the Paralympic karateka mean values, 7 taken as reference, together with 95% CIs. 8 9 When compared to elite karateka, CoM average velocity was 73% lower (p<0.001) and 10 11 acceleration was 21% lower (p=0.053). Additionally, knee RoM and peak angular velocity were 12 significantly lower, except for right knee RoM. 13 14 15 16 Fig. 1 – Fig. 2 17 18 19 DISCUSSION 20 To date very few researches have been conducted on the biomechanical profile of Paralympic 21 22 athletes13, and none reported quantitative biomechanical data concerning martial arts, despite 23 24 their global spread. To partially fill this gap, in our study we evaluated an elite Paralympic 25 karateka, with serious lower limb impairments, and we compared his kinematics features with 26 27 those of able-bodied athletes. 28 CoM kinematics 29 30 In kata, likewise the correct execution of techniques, balance control represents the main 31 2,5,15 32 performance factor for athletes’ evaluation . The karateka’s dynamic balance should be 33 maintained during constant and rapid movements. 34 35 Dynamic balance has been demonstrated to be strongly related with CoM position and 36 24 37 displacement . In Paralympic karateka, lower limb impairments could influence CoM 38 displacement, velocity and acceleration, affecting the whole-body postural control. 39 40 The current study revealed that the duration of the sequence performed by the karateka was 41 considerably longer than that of healthy Masters and Practitioners. We hypothesize that a 42 43 complex sequence of movement, such as the selected kata, requires more time to be executed 44 45 by a disabled athlete. Indeed, lower limb impairments can modify patterns of movement and 46 decrease the velocity of displacements, consequently increasing the time required to perform 47 48 the whole sequence. 49 CoM height and vertical displacement were similar to those of elite athletes: the karateka 50 51 preserved his ability to control static balance adjustments. On the other hand, CoM average 52 53 velocity and acceleration were lower. Since the angular acceleration is proportional to the 54 resultant power at the joint, this trait is probably the consequence of the inability of calf 55

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1 muscular area to express normal levels of power. Therefore, dynamic balance together with the 2 3 ability of moving the CoM in space with a high-power rate could be negatively affected. 4 Knee kinematics 5 6 In karate, techniques are performed much faster than in other martial arts3, requiring high levels 7 of speed and agility2. A high grade of muscular power is needed during kicking actions. 8 9 Moreover, elevate joints angular velocities during these movements are essential features for 10 25 11 elite karateka . 12 Considering that the knee was the joint mainly affected by the disability, notable differences 13 14 were expected. RoM values for both knees were similar between the Paralympic karateka and 15 16 Practitioners, also taking the great variability of amateurs’ parameters into account. Comparing 17 the same parameters with Masters’, a decrease of 12% for both knees occurred. In particular, 18 19 considering step 4, a transitional phase from a forward punch to a blocking technique using the 20 left limb as a single support, the right knee was considerably less flexed than both in 21 22 Practitioners and Amateurs. Since the karateka executed the movement during a unipedal 23 24 stance, it should be reasonable that the knee of the swinging leg was less flexed to maintain the 25 right foot closer to the base of support. This could be a strategy to oppose the loss of control 26 27 during the single limb stance, probably due to the weakness of the support leg. 28 Concerning the peak angular velocity, we can notice the same behavior of RoMs. Besides a 29 30 high variability, the Paralympic karateka had quite similar results compared to Practitioners, 31 32 while he showed a clear reduction of his physical performance when a comparison with Masters 33 was done. Bearing in mind the similar exposure to practice (20 vs. 17 years)15, we can state that 34 35 the strong reduction of calf muscular tissue had negatively affected the performance, entailing 36 37 reduction of RoMs and slowness of knee movements. 38 Knee kinematics is crucial in high level kata punching and kicking techniques18–21. Thus, a 39 40 recommended purpose for physical therapists and karate coaches, working with Paralympic 41 athletes, should be to recover, as much as possible, acceptable levels of strength and RoM at 42 43 the joint. Exercises improving joint mobility, during rehabilitation phase and practices, should 44 45 allow to increase knee flexion and thus maintain CoM lower during movements, enhancing 46 dynamic balance. Moreover, trainers should aim to retrieve leg extensors muscular strength, 47 48 preserving at the same time a normal hamstrings-to-quadriceps ratio to avoid injuries and 49 asymmetries26. 50 51 The study has some limitations. Firstly, the peculiarity of the athlete’s physical impairments 52 53 has not allowed a collection of data on a larger sample. Moreover, we didn’t measure muscular 54 55

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1 force output or muscular activation. Finally, to compare the karateka’s values with data from 2 3 the previous study, some joints were excluded from kinematic computations. 4 5 6 CONCLUSION 7 In this study, whole body kinematics of a Paralympic elite karateka was analyzed and compared 8 9 to the same parameters of able-bodied athletes. The physical impairments of the assessed athlete 10 11 negatively affected his lower limbs function, negatively altering key factors for kata 12 performance, like dynamic balance control and knee joints RoMs and angular velocity. 13 14 Since Paralympic categorization for karate is already in process, this case report could support 15 16 a better classification and encourage further biomechanical studies on disabled athletes. 17 18 19 NOTES 20 21 22 Acknowledgements 23 24 The authors warmly thank Alessio Castellano for his participation and Mauro Frustagli for his 25 precious suggestions. 26 27 28 Disclosure 29 30 The authors have no conflicts of interest to declare. 31 32 33 Authors’ contributions 34 35 All authors meet the criteria for authorship established by the International Committee of 36 37 Medical Journal Editors. 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55

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TABLES

29 30 31 32 33 34 Abbreviations:35 CoM, center of mass; RoM, range of motion; rms, root mean square 36 37 38

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1 TITLES OF FIGURES 2 3 4 Figure 1 Mean of Masters (circles) and Practitioners (squares) and 95% Confidence Intervals 5 6 (bars) relative to the percentage change of CoM kinematic variables, taking the Paralympic 7 karateka values as reference (0%). Negative values express a decrease while positive values 8 9 express an increase, compared to Paralympic karateka values 10 11 12 Figure 2 Mean of Masters (circles) and Practitioners (squares) and 95% Confidence Intervals 13 14 (bars) relative to the percentage change of knee kinematic variables, taking the Paralympic 15 16 karateka values as reference (0%). Negative values express a decrease while positive values 17 express an increase, compared to Paralympic karateka values 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55

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