Dresden 2014 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 20: Focus Session: Modelling of Non-linear Dynamics in Biological Movement (joint session BP/ DY)

DY 20.6: Talk

Wednesday, April 2, 2014, 15:30–15:45, ZEU 250

A COMPUTATIONAL MODEL EXPLAINS THE RELATIONSHIP BETWEEN MUSCULAR CO-ACTIVATION, REFLEXIVE CONTROL AND SELF-STABILITY — •Heiko Wagner and Kim Joris Boström — Motion Science, University of Münster, Germany

Sustaining stability during bipedal locomotion poses a challenge to the neuro-muscular-skeletal system, not only for the extremities but also for the spine. Commonly, a major role in maintaining stability is attributed to the reflex control system, which, however, is limited by the neural conduction velocity. For this reason, the concept of self-stability has been introduced, which claims that the mechanical properties of the muscular-skeletal system are exploited to maintain stability via muscular co-activation. Based on a computational model, we analyze the relationship between muscular co-activation, reflexive control and self-stability. The model includes pelvis, rib cage, and lumbar spine, as well as 90 Hill-type muscles, each endowed with a delayed monosynaptic reflex based on the lambda model. We show that muscular co-contraction not always increases the stability of the system, but rather that for a given reflex delay time there exists an optimal amount of co-contraction. These results may have an impact on the understanding of the motor control system in general, and in particular of the pathological reflex delay found in patients with low back pain.