Locomotor stability in able-bodied trunk-flexed gait across uneven ground

Occlusion of the lower visual field when wearing a facial mask does not compromise gait control when stepping into a hole in older adults

Visual exproprioception obtained from the lower visual field (LVF) is used to control locomotion on uneven terrain. Wearing a facial mask obstructs the LVF and can compromise gait control. Therefore, this study aimed to investigate the effect of occluding the LVF when wearing a facial mask on gait control while walking and stepping into a hole in older adults. Fifteen older adults walked along a wooden walkway under two different surface conditions (without and with a hole [60 cm wide and long, with a depth of 9.5 cm] and three visual conditions (control, mask, and basketball goggles with an occluded LVF). We found that occlusion of the LVF with masks or goggles did not affect the adaptations necessary to step into a hole. Neither behavioral (gait speed, margin of stability, foot landing position) nor neuromuscular (EMG activation and co-activation) parameters were affected by either visual manipulation. Older adults used a downward head pitch strategy to compensate for visual obstruction and plan the anticipatory adjustments to step into the hole. The absence of lower limb visual exproprioception due to wearing a mask did not affect locomotion control when stepping into a hole in older adults. Older adults compensated for the obstruction of the LVF through head downward tilt, which allowed them to obtain visual information about the hole two steps ahead to make anticipatory locomotor adjustments.

Legged locomotion over irregular terrains: state of the art of human and robot performance

Legged robotic technologies have moved out of the lab to operate in real environments, characterized by a wide variety of unpredictable irregularities and disturbances, all this in close proximity with humans. Demonstrating the ability of current robots to move robustly and reliably in these conditions is becoming essential to prove their safe operation. Here, we report an in-depth literature review aimed at verifying the existence of common or agreed protocols and metrics to test the performance of legged system in realistic environments. We primarily focused on three types of robotic technologies, i.e., hexapods, quadrupeds and bipeds. We also included a comprehensive overview on human locomotion studies, being it often considered the gold standard for performance, and one of the most important sources of bioinspiration for legged machines. We discovered that very few papers have rigorously studied robotic locomotion under irregular terrain conditions. On the contrary, numerous studies have addressed this problem on human gait, being nonetheless of highly heterogeneous nature in terms of experimental design. This lack of agreed methodology makes it challenging for the community to properly assess, compare and predict the performance of existing legged systems in real environments. On the one hand, this work provides a library of methods, metrics and experimental protocols, with a critical analysis on the limitations of the current approaches and future promising directions. On the other hand, it demonstrates the existence of an important lack of benchmarks in the literature, and the possibility of bridging different disciplines, e.g., the human and robotic, towards the definition of standardized procedures that will boost not only the scientific development of better bioinspired solutions, but also their market uptake.

Multi-joint biomechanics during sloped walking in patients with developmental dysplasia of the hip

BACKGROUND

Developmental dysplasia of the hip is characterized by abnormal acetabular and femoral geometries that alter joint loading and increase the risk of hip osteoarthritis. Current understanding of biomechanics in this population remains isolated to the hip and largely focused on level-ground walking, which may not capture the variable loading conditions that contribute to symptoms and intra-articular damage.

METHODS

Thirty young adult females (15 with dysplasia) underwent gait analysis during level, 10° incline, and 10° decline walking while whole-body kinematics, ground reaction forces, and electromyography (EMG) were recorded. Low back, hip, and knee joint kinematics and internal joint moments were calculated using a 15-segment model and integrated EMG was calculated within the functional phases of gait. Dependent variables (peak joint kinematics, moments, and integrated EMG) were compared across groups with a one-way ANOVA with multiple comparisons controlled for using the Benjamini-Hochberg method (α = 0.05).

FINDINGS

During level and incline walking, patients with developmental dysplasia of the hip had significantly lower trunk flexion angles, lumbar and knee extensor moments, and erector spinae activity than controls. Patients with developmental dysplasia of the hip also demonstrated reduced rectus femoris activity during loading of level walking and increased gluteus maximus activity during mid-stance of decline walking.

INTERPRETATION

Patients with developmental dysplasia of the hip adopt compensations both proximal and distal to the hip, which vary depending on the slope of walking. Furthering the understanding of multi-joint biomechanical compensations is important for understanding the mechanism of osteoarthritis development as well as secondary conditions.

Dynamic postural control during (in)visible curb descent at fast versus comfortable walking velocity

BACKGROUND

The unexpectedness of ground-contact onset in stepping down due, e.g., to a camouflaged curb during ongoing gait may impose potential postural control challenges, which might be deteriorated when walking faster.

RESEARCH QUESTION

Does traversing camouflaged versus visible curbs, at a fast walking velocity, induce more unstable body configurations, assessed by a smaller anteroposterior "margin of stability" (MoS)?

METHODS

For twelve healthy participants, we investigated MoS at foot touchdown in descent and in the first recovery step from 0- and 10-cm visible and camouflaged curbs at comfortable (1.22 ± 0.08 m/s) and fast (1.71 ± 0.11 m/s) walking velocities. Three-way (velocity, elevation, visibility) and two-way (velocity, visibility) repeated-measurement ANOVAs were performed to determine their interactions on MoS, and its determining parameters, during curb negotiation and recovery step, respectively.

RESULTS

No greater postural instability when traversing a camouflaged versus visible curb at a faster walking velocity during curb descent, indicated by no three-way interaction effects on MoS. However, an elevation-by-visibility interaction showed a dramatic decrease of MoS when descending a 10-cm camouflaged versus visible curb. This was because of a farther anterior displacement of center-of-mass with a larger velocity. Furthermore, the walking velocity was independently associated with a smaller MoS and a more anteriorly-shifted center-of-mass with a higher velocity. In the recovery step, participants demonstrated a reduced stability of the body configuration when walking faster or recovering from a camouflaged than from a visible curb. The mentioned result implies that the potential to increase the base-of-support to compensate for an increased center-of-mass velocity, induced by an increased walking velocity, is limited.

SIGNIFICANCE

Despite a significant independent main effect of walking velocity, a more unstable postural control observed during traversing of camouflaged versus visible curbs was found not to be walking velocity-related in young individuals. Further research, including elderly may shed more light on these results.