title: Repeated Kicking Actions in Karate: Effect on Technical Execution in Elite Practitioners.
abstract: OBJECTIVE
  Training in martial arts is commonly performed by repeating a technical action continuously for a given number of times. This study aimed to investigate if the repetition of the task alters the proper technical execution, limiting the training efficacy for the technical evaluation during competition. This aim was pursued analyzing lower-limb kinematics and muscle activation during repeated roundhouse kicks.
  
  
  METHODS
  Six junior karate practitioners performed continuously 20 repetitions of the kick. Hip and knee kinematics and sEMG of vastus lateralis, biceps (BF), and rectus femoris were recorded. For each repetition, hip abduction-adduction and flexion-extension and knee flexion-extension peak angular displacements and velocities, agonist and antagonist muscle activation were computed. Moreover, to monitor for the presence of myoelectric fatigue, if any, the median frequency of the sEMG was computed. All variables were normalized with respect to their individual maximum observed during the sequence of kicks. Linear regressions were fitted to each normalized parameter to test its relationship with the repetition number.
  
  
  RESULTS
  Linear-regression analysis showed that, during the sequence, the athletes modified their technique: Knee flexion, BF median frequency, hip abduction, knee-extension angular velocity, and BF antagonist activation significantly decreased. Conversely, hip flexion increased significantly.
  
  
  CONCLUSIONS
  Since karate combat competitions require proper technical execution, training protocols combining severe fatigue and technical actions should be carefully proposed because of technique adaptations. Moreover, trainers and karate masters should consider including specific strength exercises for the BF and more generally for knee flexors.
authors: Dept of Movement, Human and Health Sciences, University of Rome "Foro Italico", Rome, Italy.
authors: Federico
authors: F
authors: Quinzi
authors: Valentina
authors: V
authors: Camomilla
authors: Alberto
authors: A
authors: Di Mario
authors: Francesco
authors: F
authors: Felici
authors: Paola
authors: P
authors: Sbriccoli
mesh_terms: D000293:Adolescent; D056352:Athletes; D054874:Athletic Performance / Q000502:physiology*; D001696:Biomechanical Phenomena; D004576:Electromyography; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D016014:Linear Models; D008297:Male; D016139:Martial Arts / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D016059:Range of Motion, Articular