2018, Volume 14, Issue 1
Relationships of the expertise level of taekwondo athletes with electromyographic, kinematic and ground reaction force performance indicators during the dolho chagui kick
Pedro Moreira1, Emerson Franchini2, Ulysses Ervilha3, Marcio Goethel4, Adalgiso Cardozo4, Mauro Gonçalves4
1Laboratory of Biomechanics, University of São Paulo (UNESP), Brazil
2Escola de Educação Física e Esporte da USP, Universidade de São Paulo, Brazil
3Physical Education, Universidade de São Paulo, Escola de Artes, Ciências e Humanidades, Brazil
4Departamento de Educação Física, Universidade Estadual Paulista Júlio de Mesquita Filho, Instituto de Biociências de Rio Claro, Brazil
Author for correspondence: Pedro Moreira; Laboratory of Biomechanics, University of São Paulo (UNESP), Brazil; email: sarmet_treinamento[at]hotmail.com
Background and Study Aim: Taekwondo is an Olympic combat sport in which the outcome of the match is determined by points scored by kicking. By the competition rules, the roundhouse kick directed to the head (dollyo chagui) concedes the tripling of points, compared to that directed to the chest height. The aim of the study is knowledge about kinematic and neuromuscular indicators of the dollyo chagui (DC) executed by elite and subelite taekwondo athletes.
Material and Methods: Seven elite (23.6 ±2.1 years old; 69 ±9.5 kg; 168 ±5 cm) and 7 subelite (22.4 ±1.3 years old; 66.8 ±14.2 kg; 174 ±11 cm) black belt taekwondo athletes were evaluated on the DC kick performance. Biomechanical measures included angular and linear velocities of leg and pelvis, ground reaction force, premotor time, reaction time, kicking time and cocontraction index (CI) of EMG activation of 8 leg muscles (vastus lateralis, biceps femoris, rectus femoris, tensor fasciae latae, adductor magnum, gluteus maximus, gluteus medium and gastrocnemius lateralis), obtained through the analysis of DC kicks.
Results: Timing indicator and CI were lower (p<0.05) in an elite group, while linear peak velocities (toe, ankle and knee), angular velocities (knee and hip), and ground reaction force (GRF) were higher (p<0.05) in the elite than in the subelite group. The reaction time, cocontraction and speed of kicks are discriminant factors concerning competitive level.
Conclusions: The specific neuromuscular and technical differences between groups found in this study indicate that to improve the performance of subelite athletes these indicators could be useful in monitoring their training status. Furthermore, starting to contract specific muscles early and to perform the kicking phase with the gluteus maximum more relaxed is associated with a more efficient high kick performance. If a coach uses this information to design specific training methods, there could be a potential to improve the kick performance of the athletes.
Key words: velocity, reaction time, cocontraction, biomechanic