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.     

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.