Mid-swing Phase Research Articles

족저굴곡과 무릎 신전 토크를 이용한 보행 재활 훈련용 장하지 보조기 개발

The purpose of this study was to test the effectiveness of a prototype KAFO (Knee-Ankle-Foot Orthosis) powered by two artificial pneumatic muscles during walking. We had previously built powered AFO (Ankle-Foot Orthosis) and KO (Knee Orthosis) and used it effectively in studies on assistance of plantaflexion and knee extension motion. Extending the previous study to a KAFO presented additional challenges related to the assistance of gait motion for rehabilitation training. Five healthy males were performed gait motion on treadmill wearing KAFO equipped with artificial pneumatic muscles to power ankle plantaflexion and knee extension. Subjects walked on treadmill at 1.5 km/h under four conditions without extensive practice: 1) without wearing KAFO, 2) wearing KAFO with artificial muscles turned off, 3) wearing KAFO powered only in plantaflexion under feedforward control, and 4) wearing KAFO powered both in plantaflexion and knee extension under feedforward control. We collected surface electromyography, foot pressure and kinematics of ankle and knee joint. The experimental result showed that a muscular strength of wearing KAFO powered plnatarfexion and knee extension under feedforward control was measured to be lower due to pneumatic assistance and foot pressure of wearing KAFO powered plnatarfexion and knee extension under feedforward control was measured to be greater due to power assistance. In the result of motion analysis, the ankle angle of powered KAFO in terminal stance phase was found a peak value toward plantaflexion and there were difference of maximum knee flexion range among condition 2, 3 and 4 in mid-swing phase. The current orthosis design provided plantaflexion torque of ankle jonit in terminal stance phase and knee extension torque of knee joint in mid-swing phase.

The role of strategy selection, limb force capacity and limb positioning in successful trip recovery

Background Fall occurrence, mainly due to tripping, increases with age. There are two main strategies of trip recovery: elevating and lowering. Strategy selection depends on trip stimulus timing within the swing phase of walking, but the choice and ultimate success of a strategy selection may also depend on individual physical characteristics. The aim of this study was to investigate: 1) recovery strategy choice by younger and older adults when perturbed in the ‘strategy overlap’ mid-swing phase, and 2) whether the interaction between recovery limb positioning and recovery limb force capacity determines recovery success in elevating strategy recoveries and accounts for strategy selection. Methods A group of older (65–75 years) and a group of younger adults (20–35 years) completed a trip recovery protocol in a laboratory environment. An inverted pendulum model was developed to investigate how walking speed, recovery limb positioning and recovery limb force interacted and influenced successful trip recovery when perturbed in different swing phases. Findings Older adults always adopted a lowering strategy when perturbed in late mid-swing (60–80%), while younger adults also adopted elevating strategies. Simulations showed that, when perturbed later in swing, a larger recovery step and higher recovery limb force were required for successful recovery. Interpretation We suggested that a combination of insufficient recovery limb strength, response time and movement speed make it difficult for older adults to achieve a large enough recovery step for a successful elevating strategy recovery when perturbed later in mid-swing.

Effect of sensory inputs on the soleus H-reflex amplitude during robotic passive stepping in humans

We investigated the modulation of the soleus (Sol) Hoffmann (H-) reflex excitability by peripheral sensory inputs during passive stepping using a robotic-driven gait orthosis in healthy subjects and spinal cord-injured patients. The Sol H-reflex was evoked at standing and at six phases during passive stepping in 40 and 100% body weight unloaded conditions. The Sol H-reflex excitability was significantly inhibited during passive stepping when compared with standing posture at each unloaded condition. During passive stepping, the H-reflex amplitude was significantly smaller in the early- and mid-swing phases than in the stance phase, which was similar to the modulation pattern previously reported for normal walking. No significant differences were observed in the H-reflex amplitude between the two unloaded conditions during passive stepping. The reflex depression observed at the early part of the swing phase during passive stepping might be attributed to the sensory inputs elicited by flexion of the hip and knee joints. The present study provides evidence that peripheral sensory inputs have a significant role in phase-dependent modulation of the Sol H-reflex during walking, and that the Sol H-reflex excitability might be less affected by load-related afferents during walking.

Relevance of botulinum toxin injection and nerve block of rectus femoris to kinematic and functional parameters of stiff knee gait in hemiplegic adults

Stiff knee gait (SKG) is common in hemiplegic patients. The main focus of treatment is rectus femoris (RF) spasticity. The aims of this study were to evaluate the effect of botulinum toxin injection (BTI) in the RF muscle on peak knee flexion during swing phase and its quantitative and functional impact on gait. We also wished to evaluate the correlation between the effects of nerve block and BTI on peak knee flexion. 10 adult hemiplegic subjects (> 6 months post stroke or traumatic brain injury) with SKG and inappropriate RF EMG activity during mid-swing phase were included. 3D gait analysis, clinical and functional assessments (Timed Up and Go test, 10 m walk test, 6 min walk test and the time taken to ascend and descend a flight of stairs) were performed initially, 30 min after anaesthetic block of the RF nerve and one month post BTI. After BTI, there was a significant increase in knee flexion (8° average) and a tendency towards improvement in gait and functional parameters. The effect of the nerve block on peak knee flexion was significantly correlated with the effect of BTI (11° average increase in peak knee flexion after nerve block). We challenge the relevance of RF nerve blocks in this population when EMG and kinematic data are available. Our results indicate that BTI is an effective treatment for SKG in adult hemiplegic subjects, with a significant increase in peak knee flexion, no reduction in hip flexion and a tendency towards functional improvements.

New Accelerometric Method to Discriminate Between Asymptomatic Subjects and Patients With Medial Knee Osteoarthritis During 3-D Gait

This study presents a new method to estimate 3-D linear accelerations at tibial and femoral functional coordinate systems. The method combines the use of 3-D accelerometers, 3-D gyroscopes and reflective markers rigidly fixed on an exoskeleton and, a functional postural calibration method. Marker positions were tracked by a six-camera optoelectronic system (VICON 460, Oxford Metrics). The purpose of this study was to determine if this method could discriminate between medial osteoarthritic and asymptomatic knees during gait. Nine patients with osteoarthritic knees and nine asymptomatic control subjects were included in this study. Eighteen parameters representing maximal, minimal, and range of acceleration values were extracted during the loading and preswing to mid-swing phase periods, and were compared in both groups. Results show good discriminative capacity of the new method. Eight parameters were significantly different between both groups. The proposed method has the potential to be used in comprehending and monitoring gait strategy in patients with osteoarthritic knee.

An electromyographic analysis of obligatory (hemiplegic cerebral palsy) and voluntary (normal) unilateral toe-walking

This study compares lower extremity muscle activation during gait in patients with hemiplegic cerebral palsy (CP) with healthy subjects mimicking the patients. The purpose was to understand the differences between obligatory toe-walking as observed in hemiplegic CP gait and voluntary toe-walking. The results contribute to a better understanding by distinguishing between primary deviations in muscle activity as a direct consequence of the underlying neurological pathology of hemiplegic CP and secondary, compensatory deviations due to the biomechanics of toe-walking. Surface electromyographic (EMG), kinematic and kinetic data were compared between a group of 12 hemiplegic CP patients and a group of 10 healthy subjects walking normally and when mimicking hemiplegic gait. Integrated 3D gait analysis was performed with simultaneous EMG recordings of the medial gastrocnemius, tibialis anterior, rectus femoris, and semitendinosus muscles bilaterally. The EMG pattern of the toe-walking leg in the mimicking subjects was modified in gastrocnemius and tibialis anterior as compared with normal gait. This modified muscle activation pattern showed strong similarities to that of the patients and therefore can be regarded, at least in part, as activity required for toe-walking. A possible primary gait abnormality was observed in the rectus femoris where the patients showed a burst of EMG activity in mid-swing phase in contrast to the mimicking subjects who showed normal EMG during this phase.

The Effect of a 12-week Combined Exercise Intervention Program on Physical Performance and Gait Kinematics in Community-dwelling Elderly Women

This study aimed to determine if combined exercise intervention improves physical performance and gait joint-kinematics including the joint angle and dynamic range of motion (ROM) related to the risk of falling in community-dwelling elderly women. A 12-week combined exercise intervention program with extra emphasis on balance, muscle strength, and walking ability was designed to improve physical performance and gait. Twenty participants attended approximately two-hour exercise sessions twice weekly for 12 weeks. Participants underwent a physical performance battery, including static balance, sit and reach, whole body reaction time, 10 m obstacle walk, 10 m maximal walk, 30-second chair stand, to determine a physical performance score, and received quantitative gait kinematics measurements at baseline and in 12 weeks. Significant lower extremity strength improvement 13.5% (p<.001) was observed, which was accompanied by significant decreases in time of the 10 m obstacle walk (p<.05) and whole body reaction time (p<.001) in this study. However, no significant differences were seen for static balance and flexibility from baseline. For gait kinematics, in the mid-swing phase, knee and hip joint angle changed toward flexion (p<.01, p<.05, respectively). Ankle dynamic ROM significantly increased (p<.05) following exercise intervention. The plantar flexion angle of the ankle in the toe-off phase was increased significantly (p<.01). However, other gait parameters were not significantly different from baseline. These findings from the present investigation provide evidence of significant improvements in physical performance related to the risk factors of falling and safe gait strategy with a combined exercise intervention program in community-dwelling elderly women. The results suggest this exercise intervention could be an effective approach to ameliorate the risk factors for falls and to promote safer locomotion in elderly community-dwelling women.

The Effect of Tactile Ground Surface Indicators to the Gait of Elderly with Normal Vision

Tactile ground surface indicators installed on sidewalks help visually impaired people walk safely. However, these indicators could be an extra barrier for people who do not use those indicators. In previous study, we suggest that a functional leg length discrepancy while walking on the indicators is one of the reasons for the extra movements of the lower extremities for young. This study examines the effects of these indicators to the elderly comparing the kinematic and kinetic variables of walking on 1) a path without indicators, 2) a path with normally installed indicators, and 3) a path with recessed indicators. The results suggest that walking on the normally installed indicators causes extra movements of the lower extremities such as increased minimum toe heights during the mid-swing phase by raising entire lower extremities, and functional leg length discrepancy while walking on the indicators is one of the reasons for the extra movements of the lower extremities.

On the Potential Role of the Corticospinal Tract in the Control and Progressive Adaptation of the Soleus H-Reflex During Backward Walking

When untrained subjects walk backward on a treadmill, an unexpectedly large amplitude soleus H-reflex occurs in the midswing phase of backward walking. We hypothesized that activity in the corticospinal tract (CST) during midswing depolarizes the soleus alpha-motoneurons subliminally and thus brings them closer to threshold. To test this hypothesis, transcranial magnetic stimulation (TMS) was applied to the leg area of the motor cortex (MCx) during backward walking. Motor-evoked potentials (MEPs) were recorded from the soleus and tibialis anterior (TA) muscles in untrained subjects at different phases of the backward walking cycle. We reasoned that if soleus MEPs could be elicited in midswing, while the soleus is inactive, this would be strong evidence for increased postsynaptic excitability of the alpha-motoneurons. In the event, we found that in untrained subjects, despite the presence of an unexpectedly large H-reflex in midswing, no soleus MEPs were observed at that time. The soleus MEPs were in phase with the soleus electromyographic (EMG) activity during backward walking. Soleus MEPs increased more rapidly as a function of the EMG activity during voluntary activity than during backward walking. Furthermore, a conditioning stimulus to the motor cortex facilitated the soleus H-reflex at rest and during voluntary plantarflexion but not in the midswing phase of backward walking. With daily training at walking backward, the time at which the H-reflex began to increase was progressively delayed until it coincided with the onset of soleus EMG activity, and its amplitude was considerably reduced compared with its value on the first experimental day. By contrast, no changes were observed in the timing or amplitude of soleus MEPs with training. Taken together, these observations make it unlikely that the motor cortex via the CST is involved in control of the H-reflex during the backward step cycle of untrained subjects nor in its progressive adaptation with training. Our observations raise the possibility that the large amplitude of H-reflex in untrained subjects and its adaptation with training are mainly due to control of presynaptic inhibition of Ia-afferents by other descending tracts.

Gait analysis of people walking on tactile ground surface indicators

Tactile ground surface indicators installed on sidewalks help visually impaired people walk safely. The visually impaired distinguish the indicators by stepping into its convexities and following them. However, these indicators sometimes cause the nonvisually impaired to stumble. This study examines the effects of these indicators by comparing the kinematic and kinetic variables of walking on paths with and without indicators. The results suggest that walking on the indicators causes extra movements of the lower extremities such as increased minimum toe heights during the midswing phase, increased peak hip flex moments, and increased peak hip heights. This study also suggests that a functional leg length discrepancy while walking on the indicators is one of the reasons for the extra movements of the lower extremities. Therefore, we designed a new recessed tactile surface to offset the differences of surface depth while walking on the path containing indicators, and found that the newly designed recessed tactile surface was effective in reducing the extra movements while walking on the path in which indicators were installed. These indicators may help both the visually impaired and elderly people with normal vision to walk safely.

Functional Analysis of the Thigh Muscles during Locomotion in the Garnet Galago (Galago garnetti)

This study examined the locomotor behavior of the Galago garnetti, a prosimian. The recruitment patterns of the vastus lateralis (VL) and biceps femoris (BF) were investigated, and the excursion patterns of the hip, knee, and ankle joints were estimated, during quadrupedal horizontal walking, vertical climbing, and vertical descending on poles. In horizontal walking, the period of VL muscle activity almost coincided with that of increasing knee joint angle, although the VL ceased activity at about 80% of stance phase, while the knee joint angle continued to increase. One reason that this occurs is that the opposite hindlimb touches down at roughly 80% of stance phase, so the body weight can shift to the opposite hindlimb before toe-off. Another reason is that other knee extensor muscles may assist this motion. The BF showed sustained activity in both stance and swing phase in horizontal walking, with marked activity at mid-stance and mid-swing phase. The former peak coincided with the period during which the hip joint angle increased, and the latter peak occurred when the knee was being flexed. The trunk angle with respect to the substrate and the fact that the VL did not exhibit consistent activity during vertical descending, suggests that the garnet galago supports its body mainly with the forelimbs while descending. During vertical climbing, the lower part of the body was relatively close to the substrate. The galago protracted its hindlimb further backward to support the body in stance phase. Consequently, the hip and knee joints tended to be extended more during vertical climbing than during horizontal walking or vertical descending. Therefore, during vertical climbing, it seems likely that the galago supports its body mainly with the hindlimbs.

正常歩行中の下肢筋活動様式に関する筋電図学的研究

Objectives of this paper were to elucidate essential electrical discharge patterns of lower limb muscles and their variabilities during a normal gait cycle.Subjects employed in the experiments were 217 healthy adults of both sexes, ranging in age from 18 to 22 years, and they had no disorder in the lower limb or the central nervous system in their medical history. Electromyograms (EMGs) were recorded from the Tibialis anterior (Ta), the Gastrocnemius lateral head (Gl), the Vastus medialis (Vm), the Gluteus maximus (Gm), the Rectus femoris (Rf), the Medial Hastrings (MH), and the Biceps femoris (Bf) by conventional method using surface electrodes. Angular changes of the ankle, knee and hip joints and time signals at the heel and the toe contacts with the ground were simultaneously recorded with the EMGs.The essential EMG pattern s of the lower limb muscles during a normal gait cycle were conclusively summarized: 1) The ankle joint muscles; i) The marked discharge of the Ta was observed in the period from the end of the swing phase to the early part of the stance phase, and in the period from the end of the stance phase to the early part of the swing phase. ii) The Gl showed the main discharge in the latter half of the stance phase, and showed almost complete electrical silence in the former half of the swing phase.2) The knee and hip joint muscles; i) The discharge of the Vm started at the latter half of the swing phase and increased abruptly just before or after the heel contact. The marked discharge of the Vm lasted into the first double leg support period. ii) The discharge of the Gm started at the latter half of the swing phase and increased just before or after the heel contact. The Gm showed the continuous discharge during the former half of the stance phase. iii) The main discharge of th Rf was similar to that of the Vm, and the Rf did not show distinguished activity in the former half of the swing phase. iv) The MH and the Bf showed the marked discharges from the the latter half of the swing phase to just before or after the heel contact, but little or no discharge in the former half of the swing phase.In addition to the essential EMG pattern s, the variations in the EMG patterns which were found to be within ranges of the normal activities were as follows: 1) The ankle joint muscles ; i) The distinguished discharge of the Ta at about the mid-swing phase appeared in about 85% of the subjects. ii) The discharge variation of the G1 was hardly observed during the gait cycle.2) The knee and hip joint muscles; i) The discharge of the Vm was seen around the mid-stance phase and in the second double leg support period in about 20% of the subjects. ii)The discharge variations of the Gm were similar to those of the Vm. iii) The discharge of the Rf appeared around the mid-stance phase in less than 20% of the subjects and at the end of the stance phase in about 80%. iv) In about 60% of the subjects the marked discharges of the MH and the Bf in the latter half of the swing phase decreased or disappeared abruptly around the heel contact; however, in the other 40%, the discharges continued until the midstance phase. The discharges of the MH and the Bf at the end of the stance phase were observed in less than 20% of the subjects.The marked discharges of the MH and the Bf decreased or disappeared abruptly at the moment when the Rf abruptly increased its electrical activity around the heel contact, and the spike sessation lasted until the moment when the Rf decreased its activity. It was suggested that the spike inhibition in the MH and the Bf might be due to an antagonistic inhibition caused by facilitation of the Rf.