ABSTRACT

　Severe head and neck injuries occasionally occur in collision sports such as Judo or Rugby football. Degenerative changes in the cervical spine including abnormal alignment, spur formation and disc space narrowing are risk factors for severe injuries. It is also well known that neck muscle strength is one of the important factors for the prevention of severe injuries and degenerative disorders. The aim of this study future was to assess the relationship between the neck muscle strength and radiographic findings of the cervical spine among collision sports players.We hypothesized that poor muscle strength and unbalabced neck muscle flexion/extension strength ratio maybe associated with degenerative cervical findings. 168 judo-players （22-32 years old） and 203 rugby football-players （18-30）underwent neck extension and flexion muscle strength measurement, and 55 judo-players and 58 rugby players underwent cervical radiographical examination. Cervical alignment was classified as normal, straight, kyphosis, and sigmoid according to the Borden & Rechitman method. Disc space narrowing and spur formation were also measured according to the Kondo method and the Nathan classification. Height, weight, neck flexion and extension strength, flexion/extension ratio of the judo group ware higher than that of the rugby group with stastical significance. However, there were no significant difference of result/weight value （Judo:flexion;2.39N, extension;3.38N. ratio;0.71,Rugby:flexion;2.37, extension; 3.41, ratio; 0.70）．In Judo group, sigmoid deformity group （420±50.2N） showed significantly higher neck extension strength compared with normal group （331.7± 48.4N, p<0.05）．At the factor of flexion/extension muscle strength ratio, straight（0.67） and kyphosis （0.63） group showed significantly lower value compared with normal group （0.78. p<0.05） in Judo. In Rugby group, the presence of spur formation group （0.54） showed lesser flexion/extension muscle strength ratio compared with normal group （0.68），significantly（p<0.05）．Neck muscle strength is one important factor to prevent and reduce the severe neck injury or cervical spine abnormal findings. From this study, not only the value of muscle strength,but also the flexion/extension ratio provide important contribution for these findings. Lower flexion/extension neck muscle strength ratio is one of the risk factors of cervical spine issues for collision sports players.

DECENTE SPORTS SCIENCE Vol.41/The DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE