Figure 6. Similar time course of after-contraction movement and movement induced by muscle vibration.

Example from one subject showing similarity in the velocity of non-volitional arm abduction movements induced by a ‘control type of conditioning procedure’ (A) and by vibration applied over the deltoid muscle (B). In A, the initial downward deflection in the goniometer trace illustrates the passive arm return movement following the conditioning ‘hold-short’ abductor contraction.