Fig. 5

An example of the ability of the PerStBiRo system to detect (green and red circles) and train a reactive balance response during announced perturbations. Perturbations of 2.5° (little humps in the black lines). Figure 5a –A sample of 30 s that represents the 86 years old trainee’s inability at the beginning of the training to actively respond to announced external perturbations at low magnitudes, accelerations, and velocities that were provided as right–left 2.5° unannounced tilt [shoulder purple line (α1) shows mismatch between responses and perturbations (humps in black line)[. Figure 5b –A sample of 30 s that represents the trainee’s ability to consistently react at the end of that training session [purple line (α1) reacts in the opposite direction and related to the black line perturbations]. In cases of low unannounced perturbation magnitudes (2.5° tilt), the PerStBiRo system identified an effective balance reaction, but does not return the PerStBiRo system back to its vertical position; thus. no sensorimotor feedback is given