• Z. Ning
  • A. Faro


The purpose of this study was to analysize characteristics of isokinetic strengths of knee joint among the athletes from four events and to study isokinetic factors of knee joint which have most profound influences on separating the athletes from different events. Sixty one college male athletes from football, karate, water sport and track and field served as subjects in this study. An isokinetic dynamometer (Cybex 11 6000, Lumex, Inc.) was employed to measure strength of both extensors and flexors at the knee joint of dominant side at angular velocities of 60, 180, 300, 400 and 500 deg/sec for concentric contraction. The Digitest 1000 (Ergojump Bosco Sys-tem) were used to test squad jump- and counter movement vertical jump. ANOVA following by Tukey-HSD post-hoc test, Pearson Correlation, and Discriminant Analysis were employed for statistical analysis. PTBW- peak torque of body weight % in this study shows a trend that the strength of knee extensors and flexors decrease obviously as the velocities of movement (shortening velocity of the muscles) in-crease. There exist significant differences (Pe0.01) of PTEBWs-peak torques of ex- tensor of body weight %, and PTFBWs-peak torques of flexor of body weight % between four groups. In PTEBWs, track and field group has the highest percent- ages in all different velocities from 60 to 500 deg/s, which indicates that athletes of this group have the strongest relative ex- tensor strength comparing with other three groups. Nevertheless, there is the smallest decreasing percentage in athletes group 45.06% in PTEBW when the velocity increases from 60 to 300 deg/s, the decreasing rates of other three groups are larger than that of track and field group, 46.16% for karate, 47.02% for soccer and 48.35% for water sport. It is concluded that track and field group has the best perform- ance of knee extensors as the speed of movement increases among four group players. PTRs of athletes and soccer players are significantly larger than those of karate and water sport groups as the velocities increase. Which indicates that track and field and soccer groups maintain a better balance between knee flexors and extensors than water sport and karate group do. Correlation analysis also shows there are significant correlation between the performance of the two field tests and isokinetic variables. The result of discriminant analysis in this study shows that PTEBW5OO-peak torque of body weight % at 500 degls and PTR18O-peak torque ratio of flexors/extensors at 180 deg/s are the two most important isokinetic variables in separating the four groups. The characteristics underlying performance in these two isokinetic variables included are the same characteristics underlying performance in those isokinetic variables not included in discriminate functions.