The minimum toe clearance (MTC) results from the coordination of all bilateral lower limb body segments, i.e., a redundant kinematic chain. We tested the hypothesis that repeated exposure to trip-like perturbations induces a more effective covariation of limb segments during steady walking, in accordance with the uncontrolled manifold (UCM) theory, to minimize the MTC across strides. Twelve healthy young adults (mean age 26.2 ± 3.3 years) were enrolled. The experimental protocol consisted of three identical trials, each involving three phases carried outin succession: steady walking (baseline), managing trip-like perturbations, and steady walking (post-perturbation). Lower limb kinematics collected during both steady walking phases wereanalyzed in the framework of the UCM theory to test the hypothesis that the reduced MTC variability following the perturbation can occur, in conjunction with more effective organization of the redundant lower limb segments. Results revealed that, after the perturbation, the synergy underlying lower limb coordination becomes stronger. Accordingly, the short-term effects of the repeated exposure to perturbations modify the organization of the redundant lower limb-related movements. In addition, results confirm that the UCM theory is a promising tool for exploring the effectiveness of interventions aimed at purposely modifying motor behaviors.

Simulators for gastrointestinal (GI) endoscopy offer the opportunity to train and assess clinician skills in a low-risk environment. Physical simulators can enable direct instrument-to-organ interactions not provided by virtual platforms. However, they present scarce visual realism and limited variability in their anatomical conditions. Herein, we present an innovative and low-cost methodology for the design and fabrication of modular silicone colon simulators. The fabrication pipeline envisages parametric customization and development of 3D-printed molds for silicon pouring to obtain colon segments. The size of each colon segment is based on clinical data extracted from CT colonography images. Straight and curved segments are connected through silicone conjuncts to realize a customized and modular monolithic physical simulator. A 130 cm-long colon simulator prototype with assorted magnetically-connected polyps was fabricated and laid on a custom-made sensorized abdominal phantom. Content, face and construct validity of the designed simulator were assessed by 17 GI endoscopists. In summary, this work showed promising results for improving accessibility and flexibility of current colonoscopy physical simulators, paving the way for modular and personalized training programs.