ORIGINAL ARTICLE Coordinative intra-segment indicators of karate performance Authors’ Contribution: Márcio Fagundes Goethel1ABCD, Ulysses Fernandes Ervilha1BCD, Pedro Vieira A Study Design 2BD 1D 2AD B Data Collection Sarmet Moreira , Venicius de Paula Silva , Antonio Roberto Bendillati , C Statistical Analysis Adalgiso Coscrato Cardozo2ABE, Mauro Gonçalves2ABE D Manuscript Preparation E Funds Collection 1 Sensory-Motor Interactions Research Group, University of São Paulo, São Paulo, Brazil 2 Department of Physical Education, São Paulo State University, Rio Claro, São Paulo, Brazil Received: 27 June 2019; Accepted: 30 July 2019; Published online: 23 August 2019 AoBID: 12922 Abstract Background and Study Aim: Whether from the lower or upper limbs, intersegmental coordination is required at a high level in the blows of various martial arts modalities, with karate being no exception. In karate, precision, high speed, and tech- nique are the hallmarks of attack, counterattack, and defence. The aim of this study was the phase relation- ship between the proximal and distal joints during the execution of two technique of stroke karate: the punch gyaku tsuki and the kick mae geri. Material and Methods: The study included 14 male athletes, equally divided into 2 subgroups according to their current competi- tive level: sub-elite (SEG) and elite (EG). The karate stroke performance measure used was the linear veloci- ty peak of the wrist and foot. In order to analyze the intra-segment coordination, it was applied the nonlinear dynamics approach named continuous relative phase (CRP). From the CRP curve it was obtained the peak as well as the time to reach the CRP peak. It was also compared the index of the coordinative patterns’ variabil- ity, which was obtained by calculating the average of the CRP values and standard deviation. Results: The EG group showed significantly higher values in the linear velocity peak of the wrist and foot when com- pared to the SEG. With respect to the CRP curve peak and the coordinative patterns variability, the SEG group presented significantly higher values, showing no differences in the time to reach the CRP peak. Conclusions: The EG group presented a better intra-segment coordinative capacity during the execution of strikes. The sta- bility of coordinative patterns seems to have an intimate relationship with the technical refinement. Thus, this variable can be configured also as a predictor of performance. Keywords: gyaku tsuki • horizontal axis • mae geri • nonlinear dynamics • vertical axis Copyright: © 2019, the Authors. Published by Archives of Budo Conflict of interest: Authors have declared that no competing interest exists Ethical approval: The study was approved by the local Ethics Committee Provenance & peer review: Not commissioned; externally peer-reviewed Source of support: Departmental sources Author’s address: Márcio Fagundes Goethel, University of São Paulo, Arlindo Bettio Str. 1000, 03828-000, São Paulo, Brazil; e-mail: [email protected] © ARCHIVES OF BUDO | SCIENCE OF MARTIAL ARTS 2019 | VOLUME 15 | 203 This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (http://creativecommons.org/licenses/by-nc/4.0), which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non-commercial and is otherwise in compliance with the license. Original Article INTRODUCTION Coordination noun the ability kinematics, variability, muscle activation, adap- to use two or more parts of the body at the same time to carry Whether from the lower or upper limbs, interseg- tations of neuromuscular control, and others out a movement or task [40]. mental coordination is required at a high level in [1, 14, 15, 18-26]. However, studies describ- the blows of various martial arts modalities, with ing their characteristics regarding intra-segment Neuromuscular – adjective referring to both nerves and karate being no exception. In karate, precision, coordination and variability of coordinative pat- muscles [40]. high speed, and technique are the hallmarks of terns have not yet been conducted. Therefore, attack, counterattack, and defence [1]. the important issue is knowledge about the Motor – adjective relating to muscle activity, especially phase relationship between the proximal and dis- voluntary muscle activity, and the consequent body Coordination is defined as the ability to manage tal joints involved in the gyaku tsuki (shoulder and movements [40]. the abundant or redundant degrees of freedom to elbow) and mae geri (hip and knee) executions produce a controllable system in the body move- performed by elite and sub-elite karate athletes. Performance – noun the level at which a player or athlete ment [2] – see also glossary. Nonlinear dynamics is carrying out their activity, and dynamical systems approaches are increas- The aim of this study was the phase relationship either in relation to others or in relation to personal goals or ingly being implemented in biomechanics and between the proximal and distal joints during the standards [40]. human movement research [3]. Among these execution of two technique of stroke karate: the approaches stands out the phase relationships, punch gyaku tsuki and the kick mae geri. Motor performance – the observable production of which have been used as a measure of coordi- a voluntary action, or a motor nation and a way of quantifying intrasegmen- skill. The level of a person’s tal coordination [4]. Among the techniques used performance is susceptible MATERIAL AND METHODS to fluctuations in temporary to determine the phasic relationships between factors such as motivation, arousal, fatigue, and physical two or more joints, the continuous relative phase Sample condition [41]. (CRP) stands out for simulteously relating dis- The study included 14 male volunteers, aged Punch verb to strike someone placement and angular velocity of a given move- 18-35 years, competitive practitioners of karate, or something with the fist, e.g. ment, thus providing important information in separated into two groups according to their com- in boxing or martial arts [40]. the investigation of motor control of multi-joint petitive level. An elite group consisted of 7 individ- Kick – verb 1. to strike a ball actions [5]. The CRP has been used to investigate uals, black belts and competitors at the national or with the foot 2. to strike coordinative patterns in cyclical actions [6, 7], as international level,including 2 national champions something or somebody with the foot, e.g. in martial well in non-cyclical explosive actions [8-10]. and three champions of various international com- arts 3. to make a thrashing petitions (age: 26.300 ± 6.900 years; body mass: movement with the legs, e.g. when fighting or swimming Due to the specificity of sports gestures, the coordi- 77.5 ± 12.8 kg; height: 1.7 ± 0.1 m; fat percent- 4. (in cricket) to bounce up native motor patterns (motor performance) become age: 12.6 ± 6.7 %). The sub-elite group consisted high and quickly [40]. more consistent and controlled, presenting less of 7 individuals, black belts and competitors at the Kick – noun 1. a blow with the variability of the coordinative characteristics of regional or state level (age: 27.5 ± 6.1 years; body foot, e.g. in martial arts the technical gestures as the expertise in action mass: 75.1 ± 8.9 kg; height: 1.7 ± 0.1 m; fat per- 2. a thrashing movement with the leg when swimming increases [11]. The coordination variability has been centage: 15.1 ± 5.9 %). 3. the striking of a ball with analyzed using the CRP values dispersion [12, 13]. the foot [40]. The volunteer would be excluded from the study Technique– noun a way of The gyaku tsuki is a punch executed with the if he reported severe pain, severe soft tissue performing an action [40]. advance of hand together with the advance of injury, concussion, or surgery in the six months Speed training – noun training the contralateral lower limb, in zenkutsu dachi prior to the study. that uses exercises designed to posture, in which the athlete is with one lower improve reaction times [40]. limb advanced and knee flexed and the other Experimental Protocol Dan (dan’i) – a term used to member with the hip and knee extended, both The strokes were performed on an instrumented denote one’s technical level or grade [42]. in contact with the ground [14, 15]. The mae geri target developed at the Biomechanics Laboratory is a frontal kick, considered a simple but very effi- of the São Paulo State University (UNESP). The cient technique and therefore one of the most target was equipped with LED to provide visual used kick in competitions [16]. Among the most stimuli as well as a piezoelectric sensor whose used strokes (“stroke” is an ambiguous concept function was to detect the end of the strike due – see in glossary) in the karate, the gyaku tsuki to the touch of the hand or foot on the sensor represents approximately 50% of the techniques (Figure 1, A and B). Both the LED system and the used in an karate official combat [17]. piezoelectric sensor were controlled by a micro controller board Arduino model “MEGA 2560”. The gyaku tsuki and mae geri have great prom- inence among the karate techniques and has Five strokes were carried out unilaterally, and been examined in its various features, such as started according to the visual stimulus provided 204 | VOLUME 15 | 2019 www.archbudo.com Data collection and processing The kinematic data were obtained using a Vicon system consisting of seven cameras (T10 model) with a sampling frequency of 250 frames per second, operated by software. Vicon Nexus (Vicon®). The markers used to identify the anatomical points to be used for later reconstruction of the athletes' body movements were coupled to their body according to the recommendations presented in the Plug-in-Gait model for whole body (Vicon®).