While strength patterns in aging for the knee joint have been well investigated in the concentric mode, few data are available about the behaviour in the eccentric mode and for either modus in the ankle. The purpose of this study was to compile reference data for the lower extremities in untrained men between 20 and 60 years of age to determine the influence of age, especially in the eccentric work mode. Sixty-our male subjects between 20 and 60 years were divided into four age groups. Using a LIDO ACTIVE dynamometer, maximum torque was tested for the knee between 90° to 0° and for the ankle between 30° to - 10° at velocities 60, 180, 240, 300°/s concentric, 60 and 120°/s eccentric and isometric with angles 15°, 30°, 45°, 60°, 75° for the knee and 30°, 20°,10°, 0°, - 10° for the ankle. Individual parameters for age-dependence were checked using linear correlation calculation with p < 0.01 set as significant. The peak torque (PT) of the knee extensors and flexors showed a typical course with the highest values in the eccentric and isometric mode and a decrease in the concentric mode with increasing angular velocity. In the concentric mode there was a significant negative correlation between PT and age at all angular velocities, but none for isometric and eccentric mode. The greatest maximum torque in the ankle was attained in the eccentric mode at 60°/s. The difference to the knee was smallest in this mode compared to isometric and concentric. The plantar flexion showed age-dependence at all concentric velocities, less in eccentric and none in isometric mode. There was no correlation in dorsiflexion. The influence of loss of muscle fiber and degeneration in the course of aging has thus less influence in eccentric measurements than in the concentric mode. On the contrary, it must be assumed that the high eccentric tensions which are possible due to the quasi-elastic structures in the muscle, are maintained by the increase in stiffness of the connective tissue.
Key words
Age - isokinetic strength - ankle - knee - eccentric
