Dynamic balance in elite karateka.

In karate, balance control represents a key performance determinant. With the hypothesis that high-level athletes display advanced balance abilities, the purpose of the current study was to quantitatively investigate the motor strategies adopted by elite and non-elite karateka to maintain balance control in competition. The execution of traditional karate techniques (kihon) in two groups of elite Masters (n = 6, 31 ± 19 years) and non-elite Practitioners (n = 4, 25 ± 9 years) was compared assessing body center of mass (CoM) kinematics and other relevant parameters like step width and angular joint behavior. In the considered kihon sequence, normalized average CoM height was 8% lower (p < 0.05), while CoM displacement in the horizontal direction was significantly higher in Masters than in Practitioners (2.5 vs. 1.9 m, p < 0.05), as well as CoM average velocity and rms acceleration (p < 0.05). Step width was higher in Masters in more than half of the sequence steps (p < 0.05). Results suggest that elite karateka showed a refined dynamic balance control, obtained through the increase of the base of support and different maneuvers of lower limbs. The proposed method could be used to objectively detect talented karateka, to measure proficiency level and to assess training effectiveness.

Cinemática de variáveis de técnica-chave nos flic flacs de ginastas de elite / Kinematics of key technique variables in the backward handsprings of elite gymnasts

INTRODUÇÃO: A ginástica é o esporte de habilidades fechadas mais antigo e espetacular. Contudo, parâmetros técnicos de execução geralmente são somente ensinados por treinadores experientes. Desta maneira, existe uma lacuna de informações objetivas sobre o desempenho de ginastas (referências cinemáticas). OBJETIVO: No presente estudo, tentamos quantificar movimentos de inversão linear e de hiperextensão durante a execução de flic flacs. MÉTODOS: Foi efetuada uma detecção não invasiva de flic flacs com o auxílio de um instrumento óptico eletrônico 3D. Treze marcadores esféricos retrorreflexivos (1 cm de diâmetro) foram posicionados no corpo de 9 ginastas experientes: maléolos laterais direito e esquerdo, cabeça da fíbula, trocanter maior, acrômio, olecrano, processo estiloide da ulna e vértex. Na mesma sessão e após um período de aquecimento, cada participante executou 15 repetições de flic flacs. Dez repetições forma analisadas, e os trajetos 3D das 13 manobras medidos. RESULTADOS: Em média, os homens obtiveram altura vertical maior (mulheres, 62% da altura; homens, 58%). O alinhamento dos membros inferiores foi homogêneo entre os ginastas: ângulos posteriores de joelho variaram entre 80° e 118°. Nenhuma abdução de membro inferior foi observada: a largura de joelho foi 7 cm menor do que a largura intertrocanter; a largura de tornozelo foi 8 cm menor do que a largura de joelho. Na saída do movimento, o ângulo tronco-coxa apresentou excelente alinhamento corporal, com valores bem próximos de 180°. As mulheres executaram a fase de apoio das mãos com pulsos mais próximos do que os homens (homens, 134% de largura de ombro; mulheres, 121%). CONCLUSÃO: Os resultados podem fornecer informações para melhor conhecimento, definindo assim, a execução de padrão-ouro obtida de ginastas de elite com poucas lesões.

INTRODUCTION: Gymnastics is the most ancient and spectacular closed skills sport. Nonetheless, technical parameters of performance are often taught only by experienced trainers. Thus, there is a lack of objective data about gymnastics performance (kinematics references). OBJECTIVE: In the current study, we tried to quantify linear and hyperextension back movements during performance of backward handsprings. METHODS: A noninvasive detection of backward handsprings was made using a 3D optoelectronic instrument. Thirteen spherical retro-reflective markers (1-cm diameter) were positioned on the body of 9 experienced gymnasts: right and left lateral malleolus, fibular head, greater trochanter, acromion, olecranon, styloid process of the ulna; vertex. In the same session and after a warm-up period, each participant performed 15 repetitions of backward handsprings. Ten repetitions were analyzed, and the 3D tracks of the 13 landmarks measured. RESULTS: On average, men performed longer backward handsprings than women (men, 122% of height; women, 98%); women attained larger vertical height (women, 62% of height; men, 58%). Lower limb arrangement was homogenous among the gymnasts: posterior knee angles ranged between 80° and 118°. No lower limb abduction was observed: knee width was 7 cm smaller than intertrochanter width; ankle width was 8 cm smaller than knee width. At take-off, the trunk-thigh angle presented excellent body alignment, with values very close to 180°. Women performed the handstand phase with closer wrists than men (men, 134% of shoulder width; women, 121%). CONCLUSION: The results may offer data to improve understanding, defining gold-standard execution taken from high level gymnasts with few injuries.