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.