Neda Boroushak - Ph.D student of sport Biomechanics, Faculty of physical Education and sport sciences, Mazandaran University, Babolsar, Iran
Mehrdad Anbarian - Department of sport Biomechanics, Faculty of physical Education and sport sciences, Bu Ali sina university, Hamedan, Iran

Background & Objective: Imbalances between the agonist-antagonist muscles of the knee have been linked to a greater susceptibility to injury in the knee joint. The aim of the present study was to assess the Hamstring/Quadriceps muscular strength(H/Q) ratio of elite karate athletes before and after muscular fatigue. Material &Methods: Thirteen female elite karate athletes (age: 15.5±1.5 years) were evaluated in an isokinetic dynamometer at 60◦/s, 180◦/s and 300◦/s before and after hamstring and quadriceps muscular fatigue. Paired sample T test and one way repeated measure were used for statistical analysis. α level was set at 0.05. Results: After muscular fatigue, significant decrease were found in Hamstring/Quadriceps muscular strength ratio in the knee flexors and extensors strength (P> 0.05) at the 60◦/s, 1800◦/s and 300◦/s speeds (P<0.05). No significant difference was found in the knee (H/Q) ratio between three different speeds (F=1.23; P=0.30). conclusion: Our results showed that lower limb muscle imbalances in elite female karate athletes that could predispose young karate athletes to injuries exist at the speedof 300◦/s speed and in three different speeds after fatigue protocol, but there are not any differences after fatigue between three speeds. . So we can say that fatigue can probably increase the potential of knee joint injury and particularly ACL structure

Injury,Imbalances,flexors and extensors strength,karate athletes