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
