NEUROMUSCULAR PERFORMANCE OF DOLLYO CHAGUI: COMPARISON OF SUBELITE AND ELITE TAEKWONDO ATHLETES

Aiming to compare the execution time, linear and angular speeds, ground reaction force (GRF) and electromyographic (EMG) parameters between taekwondo athletes of two different standards, 8 elite and 8 subelite black belt taekwondo athletes performed eighteen round house kicks, in two randomized height (Head and Chest), with their dominant lower limb, combining maximum impact and speed, in a selective reaction time design. Kinematic were recorded through 3D kinemetry. Timing parameters and EMG cocontraction index were significantly lower in elite group, while peak of linear (toe and knee), angular speeds (knee and hip), and GRF were significantly higher in elite group. We conclude that reaction time, duration and velocity of kick and cocontraction could be useful in selecting top level taekwondo athletes and monitoring their training status

The analysis of COP and joint position sense in university soccer players with and without ankle instability

O objetivo do estudo foi comparar o comportamento do COP e do sentido de posição articular passivo em indivíduos com e sem instabilidade de tornozelo, e correlacionar as variáveis de COP e sentido de posição articular passivo. Participaram 20 indivíduos, divididos em dois grupos: grupo estável (GE) e grupo instável (GI). A avaliação do COP foi feita com o teste de apoio unipodal, com olhos abertos e fechados sobre uma plataforma de força. O teste de reposicionamento articular passivo foi realizado com os olhos vendados. O tornozelo foi posicionado em um ângulo alvo (10° e 20°) e o dinamômetro movia passivamente o tornozelo, então os participantes eram instruídos a apertar o botão para parar o movimento quando sentissem que o tornozelo estava no ângulo alvo, obtendo assim o erro angular absoluto (EAA). Foram obtidas as variáveis: deslocamento total (DT); desvio padrão ântero-posterior (DPap) e médio-lateral (DPml); velocidade média total (VMT); velocidade média ântero-posterior (VMap) e médio-lateral (VMml). A comparação entre dados que apresentaram distribuição normal foi feita com o teste t de Student, enquanto que para DT e DPml foi utilizado o teste de Mann-Whitney. Da mesma forma, foram usados os testes de Pearson e Spearman para correlacionar as variáveis. Foi adotado α < 0,05. Houve diferença entre EAA-10° (p < 0,05). Foram encontradas fortes correlações entre: EAA-10° e VMT (p < 0,01 r = −0,867); EAA-10° e VMap (p < 0,01 r = −0,854); EAA-10° e VMml (p < 0,01 r = −0,771), na condição olhos abertos, e EAA-10° e DT (p < 0,05 r = −0,666); EAA-10° e DPap (p < 0,05 r = −0,685) e EAA-10° e VMml (p < 0,05 r = −0,766) na condição olhos fechados. Entorses de tornozelo prejudicam o sentido de posição, sem afetar o equilíbrio.The aim of the study was to compare the behavior of COP and passive ankle position sense in subjects with and without functional ankle instability. Took part in this study 20 subjects, divided into two groups: stable group (SG) and unstable group (UG). The COP evaluation was made with the single-leg balance test, with eyes opened and closed, on a force plate. The passive ankle position sense test was performed with subjects blindfolded. The ankle was positioned in a target angle (10° and 20°) and the dynamometer moved passively the ankle, then the subjects were instructed to push the stop button when they feel that the ankle was on the target angle, obtaining the absolute angular error (AAE). The following variables were obtained: total displacement (TD); antero-posterior (SDap) and medio-lateral standard deviation (SDml); total mean velocity (TMV); antero-posterior (MVap) and medio-lateral mean velocity (MVml). The comparison between the data with normal distribution was made with the Student's t test, while to the TD and SDml was used the Mann-Whitney test. The correlations were performed with the Pearson and Spearman tests. We adopted α < 0.05. We observed difference between AAE-10° (p < 0.05). Strong correlations were found between: AAE-10° and TMV (p < 0.01 r = −0.867); AAE-10° and MVap (p < 0.01 r = −0.854); AAE-10° and MVml (p < 0.01 r = −0.771), with eyes opened, and AAE-10° and TD (p < 0.05 r = −0.666); AAE-10° and SDap (p < 0.05 r = −0,685) and AAE-10° and MVml (p < 0.05 r= −0.766) with eyes closed. Ankle sprains harm the joint position sense without affecting the balance

Análise de parâmetros neuromusculares e cinemáticos dos chutes Bandal Chagui e Dolhô Chagui do Taekwondo

Abstract The purpose of this study was to compare kinematic and neuromuscular parameters of roundhouse (RK) kick in athletes of two different standards. 7 elite and 7 sub-elite black belt taekwondo athletes performed eighteen RK, directed to two randomized height (9 to the head and 9 to the chest), with their dominant lower limb, combining maximum impact and speed, in a selective reaction time design. Angular and linear velocities of dominant leg and pelvis were recorded through 3D kinemetry. Ground reaction force parameters (GRF) were evaluated by force platform and surface electromyographic (sEMG) signals were recorded through wireless system from the Vastus Lateralis (VL), Biceps Femoris (BF), Rectus Femoris (RF), Tensor Fasciae Lata (TFL), Adductor Magnum (AM), Gluteus Maximum (GM), Gluteus Medium (Gmed) and Gastrocnemius Lateralis (GL) muscles of the kicking leg. EMGs data were rectified, filtered and normalized to the maximal value obtained for each muscle over all trials; cocontraction (CI) indexes of antagonist vs. overall (agonist and antagonist) activity were computed for hip abduction and hip and knee in flexion and extension. Premotor time of each muscle, reaction time and kicking time was assessed as well. Timing parameters and sEMG cocontraction index were significantly lower in elite group, while peak of linear (toe, ankle and knee), angular velocities (knee and hip), and GRF were significantly higher in elite than in sub-elite group. We conclude that reaction time, cocontraction, duration and velocity of kick could be useful in selecting top level taekwondo athletes and monitoring their training statu

Musculoskeletal model Gait_2392

Musculoskeletal model Gait_2392, composed of 12 rigid bodies and 92 musculotendon actuators. At the left, markers and rigid bodies are shown and, on the right, the actuators. </p

Análise de equações preditivas da gordura corporal em jovens atletas de "taekwondo"

Due to the lack of valid and accessible tests to measure the body fat percentage (BF%) of adolescent taekwondo athletes (TKDA), this study aimed to analyze six anthropometric equations in the prediction of BF% with the Dual-Energy-x-Ray (DEXA) as referential method for five TKDA (12.23 years ± 1.60). The BF% estimated by the equations were compared with DEXA values using the t-student , linear regression and Bland & Altman (B&A) tests. Only the equation of Slaughter et al. (1988) was adequated by the sample size calculation, and although it subestimated the BF% (in 4.85% ± 0.98), it showed a high correlation (R = 0.935; R² = 0.874 EPE = 1.01) and low amplitude in the limits of agreement at 95% (3.84%) by B&A in comparison to DEXA. However, this equation is adequated to predict the BF% in TKDA, if it's corrected by the adjustement equation [%G (DEXA) = 1,64 + 1,24&#8226;%G (Eq 4)] generated by linear regression.Debido a la falta de métodos accesibles válidos para medir el porcentaje de grasa del cuerpo (%G) de atletas de taekwondo adolescentes (TKDA), destinada a analizar seis ecuaciones antropométricas de predicción de %G, en cinco TKDA (12,23 años ± 1,60 ), utilizando como método de referencia la Densitometría Radiológica de Energía Dual (DEXA). El %G estimado por las ecuaciones fue comparado mediante la prueba t-student, regresión lineal y Bland & Altman (B&A) con los que se obtienen mediante DEXA. Sólo la ecuación del SLAUGHTER et al. (1988) fue adecuada para el cálculo del tamaño de la muestra y, a pesar de que había subestimado la %G (4,85 % ± 0,98 ), este mostró una alta correlación (R = 0,935 ; R2 = 0,874 EPE = 1,01 ) y baja amplitud dentro de los límites de concordancia con el 95% (3,84 %) por B&A en comparación con la DEXA. Por lo tanto, esta ecuación demostró ser adecuada para la predicción de %G en TKDA, desde que corrigida mediante la siguiente ecuación de ajuste [ %G (DEXA) = 1,64 + 1,24 &#8226; %G (eq 4)] generada mediante regresión lineal.Devido à falta de métodos acessíveis válidos para mensurar o percentual de gordura corporal (%G) de taekwondistas adolescentes (TKDA), objetivou-se analisar seis equações antropométricas de predição do %G, em cinco TKDA (12,23 anos ± 1,60), utilizando como método de referência a Densitometria Radiológica de Dupla Energia (DEXA). Os %G estimados pelas equações foram comparados pelo teste t-student, regressão linear e Bland e Altman (B&A) com os obtidos por DEXA. Apenas a equação de Slaughter et al. (1988) foi adequada pelo cálculo amostral, e embora tenha subestimado o %G (em 4,85% ± 0,98), esta apresentou alta correlação (R = 0,935; R² = 0,874 EPE = 1,01) e baixa amplitude nos limites de concordância a 95% (3,84%) pelo B&A em comparação com a DEXA. Portanto, esta equação mostrou-se adequada para a predição do %G em TKDA, desde que seja corrigida pela equação de ajuste [%G (DEXA) = 1,64 + 1,24 &#8226; %G (Eq 4)] gerada pela regressão linear

Development of a low cost force platform for biomechanical parameters analysis

<div><p>AbstractIntroduction: The maintenance of balance and body orientation during standing is essential to perform different activities. One of the devices used to measure balance them is the force platform. This device measures the ground reaction force (GRF) and displacement of the center of pressure (COP), both biomechanical parameters involved in human motion. This article proposes a new design for non-commercial low-cost force platforms for scientific research purposes. Methods for calibration and validation are also described. Methods A force platform, developed according to International Standards of Measurement and dedicated to measuring feet contact forces was built for approximately one tenth of the cost of commercial platforms. Calibration was performed by loading known masses, centralized or distributed, on the platform. An experimental study was conducted with four volunteers in different conditions to validate and verify the practical applicability of the device. Results The platform calibration showed an adequate connectivity, linearity and reliable measurement of the variables proposed in this research, being suitable for studies of human postural behavior. Conclusion Based on the validation results, we believe the low-cost platform can be used as stabilometric device to measure postural control and balance in clinical or sports experiments. However future studies will be required to provide a final validation and compare its performance with other force platforms.</p></div

The Relationship between the Color of Electronic Protectors and the Outcome in Taekwondo Matches: Is There Fairness in National Competitions?

Although research on the effect of color in taekwondo has involved several international competitions, no previous study has investigated the presence of this phenomenon in national-level competitions. The main objective of this study was to analyze the relationship between the color protectors and success in 1155 taekwondo matches of the Italian and Uzbekistan Senior Championships (ITA-SC and UZB-SC) (2019 and 2021). The results showed no relationship between the color protectors and the match outcome, in both ITA-SC and UZB-SC (p = 0.71, V = 0.01; p = 0.61, V = 0.02). Moreover, no relationship emerged between the color protectors and the match outcome in the four editions of the SC. Stratifying analyses by weight category and sex, males showed positive relationships between the color blue/red and winning the match in 3 and 1 of 16 weight categories, respectively. Contrary, females showed positive relationships between the color blue/red and winning the match in 1 and 3 of 16 weight categories, respectively. Analyzing the two national contexts found that, in both the Italian and Uzbek contexts, matches in 2 and 2 of 16 weight categories were won by athletes wearing blue and red protectors, respectively. Significant relationships emerged between the color blue and winning the match with small asymmetry in the men&rsquo;s UZB-SC and between the color red and winning the match with large asymmetry in the female ITA-SC. The implementation of the electronic point recording system for the body and head has had a positive impact on fairness in national taekwondo competitions, did not detect any effect of color related to cultural context, and did not allow for the color red to tip the scales between losing and winning in matches between athletes of similar ability and strength