Compass diagrams displaying theoretical “net activation directions” for various muscle groups. Net activation direction suggests muscle group is most active when system COM is being accelerated in that direction as a result of all muscles activating to directly counter (i.e., oppose) disturbance from neutral standing. Activation direction (θ) results displayed for respective able-bodied model (solid arrow) and EMG (broken arrow) data for the following right-side (RT) muscle groups: SOL = Soleus (θ = 183°, 153°±13°), TA = Tibialis Anterior (θ = 40°, 35°±11°), VAST = Vastus Intermedius (θ = 181°, 46°±13°), SEM = Semimembranosus (θ = 286°, 222°±12°), ADD = Adductor Magnus (θ = 234°, 207°±13°), GMAX = Gluteus Maximus (θ = 164°, 319°±17°), GMED = Gluteus Medius (θ = 130°,114°±19°), ES = Erector Spinae (θ = 75°, 41°±12°).