Co-contraction of Antagonist Muscles

Co-contraction is the simultaneous contraction of antagonist muscles. It has no impact on joint torque yet it increases joint damping because of the non-linear force-velocity properties of muscle tissue. Co-contraction thus allows the nervous system to actively control limb damping.

We analysed the stability of co-contracting muscle in a simulated biomechanical limb with realistic force-length-velocity relationships. We found that co-contraction not only modulates joint damping but that it also effects postural stability. Under certain conditions, co-contracting muscles can even induce multiple stable equilibrium points.

Heitmann S, Ferns N, Breakspear M (2012). Muscle co-contraction modulates damping and joint stability in a three-link biomechanical limb. Frontiers in Neurorobotics 5:5.