An isokinetic study of combined activity of the hip and knee extensors

The purpose of this study was twofold: to derive isokinetic concentric and eccentric normal strength values obtained during combined activity of the knee and hip extensors and to compare these values with those based on testing of knee extensors only. Fifteen men took part in the study. Combined extension was tested in the supine position with the knee and hip at an initial position of 95 °. Knee extension was tested in the seated position with the knee at the same initial position. The range of motion and angular velocities were equal in both configurations: 15 ° and 8 ° s−1 and 15 ° s−1 respectively. The average peak force in the CKH mode was close to 10 Nm/kg bw and over 15 Nm/kg bw in the concentric and eccentric contractions respectively, whereas for the knee extensor mode the respective figures were approximately 8 Nm/kg bw and 10 Nm/kg bw. With respect to the same performance parameters, there were low and insignificant correlations between the two modes.