Unterschiedliches koordinatives Verhalten bei der exzentrischen und konzentrischen Muskelkontraktion – zahlreiche Fragen bleiben unbeantwortet

BackgroundConcentric and eccentric muscle work is characterized through different biochemical activating cascades. Concentric contraction is characterized by an ATP O2 coupling dependent interaction of the myofibril proteins Aktin and Myosin. In eccentric contraction, according to the Winding-filament hypothesis, a rotation movement around the thin filament is caused which is ATP independent. In addition, the processes of motor anticipation vary greatly between the two. This leads to the aim of the study: What are the differences in concentric versus eccentric muscle work concerning anticipation, perception and execution.Material and MethodsFive male (30 ± 9.6 years, 179 ± 3.1 cm, 78.6 ± 15.1 kg) participants absolved a test program on a Soft Robot. This entailed slow eccentric muscle work over 8 sec followed by a 2 sec concentric movement. Five male volunteers (30 ± 9.6 years, 179 ± 3.1 cm, 78.6 ± 15.1 kg) completed exercise tests on a soft robot. This included 5-minute cycles of pedaling exercise with a 8-second long eccentric braking phase of muscle work followed by a 2-second concentric extension phase at four external loads (15, 25, 35, 45 kg). Target and effective workload were online monitored and displayed to allow control of the movement cycle.ResultsIn all participants a relatively equal interindividual pattern, characterized by the difference between the predetermined force of the program and the effective used force under variable weights, was found. In eccentric contraction the deviation is relatively constant in contrast to concentric contraction where an increase was detectable.DiscussionThe pattern of motoric control seems to differ in concentric versus eccentric muscle activity. The identified interindividual differences might be a consequence of different muscle fibers (slow versus fast twitching) resulting from a different state of base fitness e.g. stop and go type athletes versus endurance athletes. The concurrent measurement of Oxygen and EMG-activity combined with muscle biopsy and the respective correlation of findings could give further hints concerning differences in motor control of concentric versus eccentric muscle action and give hints concerning the, to date, undetermined involvement of biochemical cascades.