Abstract
Background: A shift in the angle of peak torque (APT) during maximal voluntary isokinetic concentric knee flexions and extensions has been demonstrated following eccentric and stepping exercise.
Objective: To test the hypothesis that downhill marathon running is associated with a shift in the APT towards longer muscle length.
Methods: Twelve male runners performed an isokinetic muscle test three to four days before and 18 hours after a downhill marathon. Both legs were tested and the testing protocol consisted of concentric and eccentric quadriceps and hamstring contractions at 60°/s.
Results: There were no significant differences between quadriceps peak torque (PT) before and after the race. There was a bilateral shift in the APT of the quadriceps to a more extended position in the concentric but not in the eccentric testing mode.
Conclusion: Running a downhill marathon is not associated with concentric and eccentric quadriceps fatigue. Prolonged downhill running could result in changes in muscle properties expressed in a shift in the APT towards shorter muscle lengths without significant force deficits in the concentric testing mode. By contrast, there was no shift in the APT in the eccentric testing mode challenging the functional significance of moving the angle of peak maximal voluntary concentric torque of the quadriceps muscles in connection with a downhill marathon.