The Effect of Cane Use on Attentional Demands During Walking

We investigated the effects of cane use, lateral walking stability, and cane use practice on attentional demands during walking. Attentional demands were assessed using dual-task methodology with a reaction time (RT) task. Sixteen healthy young subjects performed the RT task during walking, before and after cane use practice under four conditions: with/without cane use while wearing normal/unstable shoes. Among normal shoe conditions, cane use resulted in longer RTs. In contrast, RTs were similar regardless of cane use in the unstable shoe conditions. Among conditions without cane use, unstable shoes resulted in longer RTs. In contrast, RTs were similar regardless of shoe type in the cane use conditions. This study suggests that using a cane during walking requires additional attention; however, the resulting attentional demands depend on walking stability.     

Foot Motion Character During Forward and Backward Walking With Shoes and Barefoot

Abstract

Backward walking (BW) has been extensively used in athletic training and orthopedic rehabilitation as it may have value for enhancing balance. This study identified the differences in foot intersegment kinematics (forward walking (FW) vs. time-reversed BW) and plantar pressure parameters of 16 healthy habitually shod individuals walking FW and BW using flexible shoes (SH) and under barefoot conditions (BF). BW was found to have shorter stride length (SL) and higher stride frequency (SF) under BF conditions compared with SH, which indicates a better BW gait stability under BF conditions. Decreased HX/FF dorsiflexion at HO in BW induces less plantar aponeurosis tension which may inhibit the windlass mechanism compared to FW walking. Increased forefoot relative to hindfoot (FF/HF) pronation and sequentially hindfoot relative to tibia (HF/TB) eversion combined with medially distributed plantar pressure and a higher plantar contact area in the medial side in BW–BF maybe beneficial in maintaining balance. These results indicate that BW training may be more reliable under BF conditions compared to the SH conditions based on greater sensory information feedback from the plantar area resulting in better biomechanical behavior.     

Adaptation of Neuromuscular Synergies During Intentional Constraints of Space-Time Relationships in Human Gait

Tight frequency-to-amplitude relationships are observed in spontaneous human steady gait. They can be modified, if required; that flexibility forms a fundamental basis of the intentional adaptive capabilities of locomotion. In the present experiments, the processes underlying that flexibility were investigated at both the level of joint kinematics and the level of neuromuscular synergies. Subjects (N = 4) walked at the same speed either with a preferred or a nonpreferred frequency-to-amplitude relationship (i.e., constrained, short steps at a high frequency [COS condition] or constrained, long steps at a low frequency [COL condition]); their swing and stance phases were separately analyzed. In the COS condition, increases in EMG activity were specifically required during the swing phase. In the COL condition, several muscles required increases in EMG activity during the stance phase, but decreases of the hamstring muscles were needed during the swing phase. Whereas, in preferred walking, modification of the frequency affects the EMG patterns globally (the gain increasing with the frequency in both the stance and swing phases), the present results show that changing the frequency in a constrained manner either affects the swing phase specifically or affects both phases, but in the opposite direction. That finding indicates mat a separate control is needed in both the swing and the stance phases.     

Energetic Cost and Stability during Human Walking at the Preferred Stride Frequency

The possibility that preferred modes of locomotion emerge from dynamical and optimality constraints and the energetic and dynamical constraints on preferred and predicted walking frequency are explored in this article. Participants were required to walk on a treadmill at their preferred frequency, at a frequency predicted as the resonance of a hybrid pendulum-spring model of the legs, and at frequencies ±15%, ±25%, ±35% of the predicted frequency. Walking at the preferred and predicted frequencies resulted in minimal metabolic costs and maximal stability of the head and joint actions. Mechanical energy conservation was constant across conditions. The head was more stable than the joints. The joints appeared to be in service of the head in maintaining a stable trajectory. The major findings of this study suggest a complementary relationship between energetic (physiological) and stability constraints in the adoption of a preferred frequency of walking. Multiple subsystems may be involved in constraining observed macroscopic behavior in intact biological systems. The approach and results of the study imply that a useful tack in understanding how dynamical control structures arise is to study the potential criteria that serve to act as constraints on skilled movement patterns in unimpaired and impaired populations.     

Local Dynamic Stability of the Locomotion of Lower Extremity Joints and Trunk During Backward Upslope Walking

Backward slope walking was considered as a practical rehabilitation and training skill. However, its gait stability has been hardly studied, resulting in its limited application as a rehabilitation tool. In this study, the effect of walking direction and slope grade were investigated on the local dynamic stability of the motion of lower extremity joints and trunk segment during backward and forward upslope walking (BUW/FUW). The local divergence exponents (λ_S) of 16 adults were calculated during their BUW and FUW at grades of 0%, 5%, 10%, and 15%. Mean standard deviation over strides (MeanSD) was analyzed as their gait variability. Backward walking showed larger λ_S for the abduction-adduction and rotational angles of knee and ankle on inclined surface than forward walking, while λ_S for hip flexion-extension angle at steeper grades was opposite. No grade effect for any joint existed during BUW, while λ_S increased with the increasing grade during FUW. As to the trunk, walking direction did little impact on λ_S. Still, significant larger λ_S for its medial-lateral and vertical motion were found at the steeper grades during both FUW and BUW. Results indicate that during BUW, the backward direction may influence the stability of joint motions, while the trunk stability was challenged by the increasing grades. Therefore, BUW may be a training tool for the stability of both upper and lower body motion during gait.     

Anticipatory Postural Adjustments for Altering Direction During Walking

The authors examined how individuals adapt their gait and regulate their body configuration before altering direction during walking. Eight young adults were asked to change direction during walking with different turning angles (0deg;, 45deg;, 90deg;), pivot foot (left, right), and walking speeds (normal and fast). The authors used video and force platform systems to determine participants' whole-body center of mass and the center of pressure during the step before they changed direction. The results showed that anticipatory postural adjustments occurred during the prior step and occurred earlier for the fast walking speed. Anticipatory postural adjustments were affected by all 3 variables (turn angle, pivot foot, and speed). Participants leaned backward and sideward on the prior step in anticipation of the turn. Those findings indicate that the motor system uses central control mechanisms to predict the required anticipatory adjustments and organizes the body configuration on the basis of the movement goal.     

Slower Reorientation of Trunk for Reactive Turning while Walking in Hemiparesis Stroke Patients

We examined the behavioral characteristics of reactive turning in hemiplegic stroke patients when they were informed of the turning direction just before turning was required at an unpredictable time. Eleven stroke patients and 20 healthy elderly control people were asked to initiate a turn as soon as a visual cue to inform them of the turning direction was activated unpredictably using a foot switch. Both the segmental reorientation and stepping type when turning 90° while walking were measured. The results indicated preserved segmental reorientation of the head and pelvis in stroke patients. Stroke patients showed delays in pelvic turning but not in head turning. Their delayed pelvic movement might be due to motor dysfunction and the time taken to ensure stability when deciding when to turn.