Isokinetic profiles of hamstring and quadriceps muscles in the police special force operators

Knee injuries are of concern to police. The aims of this study were to determine initial reference values for isokinetic knee extension and flexion in police special force operators to explore the conventional hamstring contraction (Hcon) quadriceps contraction (Qcon) ratio, and to determine the limb symmetry index of the quadriceps and hamstring muscles. Absolute and relative isokinetic torque of quadriceps and hamstrings were assessed in 10 police special force operators using an isokinetic dynamometer Con-Trex. Subjects performed maximal knee extension and flexion at a contraction velocity of 60 degrees/s at 90 degrees of knee flexion. Means, standard deviations, 95% confidence interval values, and effect sizes were calculated. A paired samples t-test was used to test the between-leg differences in absolute and relative torques of quadriceps and hamstring muscles and to test the between-leg difference in Hcon/Qcon ratios as well as strength asymmetries of quadriceps and hamstrings. Descriptive statistics revealed torque values similar to athletes, and paired sample t-tests showed no significant between-leg differences in torque values at a group level. Small effect sizes were observed between legs in both the absolute and relative peak torque of the hamstring muscles. While, on a group level, no Hcon/Qcon ratio disparity between legs or asymmetries were observed, individual results indicated a trend towards greater dispersion for the dominant leg and some individual results indicated an increased asymmetry in isometric strength of hamstrings. The study provides normative data for this unique police population and highlights the need for relative strength work in this population.