Analysis of characteristics required for gait evaluation of patients with knee osteoarthritis using a wireless accelerometer

BackgroundKnee osteoarthritis (KOA) is associated with reduced quality of life due to knee pain and gait disturbance. However, the evaluation of KOA is mainly based on images and patient-reported outcome measures (PROMs), which are said to be insufficient for functional evaluation. Recently, gait analysis using an accelerometer has been used for functional evaluation of KOA patients. Nevertheless, evaluation of the entire body motion is insufficient. The aim of this study was to clarify the gait characteristics of KOA patients using the distribution of scalar products and the interval time of heel contact during spontaneous walking and to compare them with healthy subjects.MethodsParticipants wore a three-axis accelerometer sensor on the third lumbar vertebra and walked for 6 min on a flat path at a free walking speed. The sum of a composite vector (CV) scalar product and a histogram for distribution were used for body motion evaluation. The CV consisted of a synthesis of acceleration data from three axes. In addition to the summation of the CV, a histogram can be created to evaluate in detail the magnitude of the waves. The amount of variation was measured in the left–right and front–back directions. Variability was evaluated from the distribution of heel contact duration between both feet measured from the vertical acceleration.ResultsKOA patients showed a smaller sum of CV that converged to small acceleration in the distribution when compared with healthy subjects. In the KOA group, the amount of variation in the forward and backward directions was greater than that in the forward direction. The variability of heel–ground interval time was greater in the KOA group than in healthy subjects.ConclusionKOA patients walked with less overall body movement, with limited movable range of the knee joint and pain-avoiding motion. The gait of the KOA group was considered unstable, with long time intervals between peaks. The increase in the amount of forward variation was thought to be due to the effect of trunk forward bending during walking. The clinical relevance of this study is that it was possible to evaluate KOA patients’ gait quantitatively and qualitatively.     

Quasi real-time gait event detection using shank-attached gyroscopes

This article describes an ambulatory gait event detection method for long-term monitoring of walking. Aminian et al. [2] have developed an automatic gait event detection algorithm based on shank-attached gyroscope signals. However, this algorithm has a drawback in that it is post-processed. We propose a modified algorithm which detects foot initial and end contact timings using the same concept as in [2], but in quasi real-time. The utilization of the knowledge on gait sequence and peak angular acceleration realizes the quasi real-time detection. Furthermore, to be practical, the algorithm has been developed to ensure the robustness of detection (i.e., without missing the gait events in various speed conditions). Validation of the algorithm using footswitches shows that the algorithm detected the end contacts earlier (−8 ms) and the initial contacts later (19 ms) than the footswitch-based method.     

Striatal dopaminergic denervation and gait in healthy adults

Parkinsonian-like motor impairments are common in the elderly. The etiology of these symptoms in the absence of clinically diagnosable Parkinson’s disease (PD) is unknown. The aim of this study was to evaluate associations between striatal dopaminergic neuron losses that occur with aging and gait in healthy adults. Forty healthy subjects aged 21–85 years old underwent [¹¹C]-β-CFT dopamine transporter (DAT) positron emission tomography (PET). Subjects were also asked to walk in a gait laboratory at their own pace. Gait variables of interest included average general spatiotemporal characteristics of walking patterns and their standard deviation reflecting gait variability. Segmented nonlinear models were used to investigate the relationship between striatal DAT activity and gait while controlling for age. Gait speed, cadence, and single and double support durations were significantly slower than age-based predictions in adults with lower striatal DAT activity (P < 0.05). After controlling for age, striatal DAT activity was not significantly associated with average step length and step width and with gait variability. We conclude that dopaminergic physiology influences certain aspects of gait independent of age-related changes. The findings of this study may augur novel therapeutic approaches to treating gait disorders in the elderly.     

Quantitative assessment of gait bradykinesia in Parkinson's disease using a portable gait rhythmogram

To quantify gait bradykinesia during daily activity in patients with Parkinson's disease (PD), we measured movement-induced accelerations over more than 24h in 50 patients with PD and 17 age-matched normal controls, using a new device, the portable gait rhythmogram. Acceleration values induced by various movements, averaged each 10 min, exhibited a gamma distribution. The mean value of the distribution curve was used as an index of the "amount of overall movement per 24h". Characteristic changes were observed in both the gait cycle and gait acceleration. During hypokinesia, the gait cycle became either faster or slower. A number of patients with marked akinesia/bradykinesia showed a reduced and narrow range of gait acceleration, i.e., a range of floor reaction forces. The results suggest that assessment of the combination of changes in gait cycle and gait acceleration can quantitatively define the severity of gait bradykinesia.     

An adaptive gyroscope-based algorithm for temporal gait analysis

Body-worn kinematic sensors have been widely proposed as the optimal solution for portable, low cost, ambulatory monitoring of gait. This study aims to evaluate an adaptive gyroscope-based algorithm for automated temporal gait analysis using body-worn wireless gyroscopes. Gyroscope data from nine healthy adult subjects performing four walks at four different speeds were then compared against data acquired simultaneously using two force plates and an optical motion capture system. Data from a poliomyelitis patient, exhibiting pathological gait walking with and without the aid of a crutch, were also compared to the force plate. Results show that the mean true error between the adaptive gyroscope algorithm and force plate was −4.5 ± 14.4 ms and 43.4 ± 6.0 ms for IC and TC points, respectively, in healthy subjects. Similarly, the mean true error when data from the polio patient were compared against the force plate was −75.61 ± 27.53 ms and 99.20 ± 46.00 ms for IC and TC points, respectively. A comparison of the present algorithm against temporal gait parameters derived from an optical motion analysis system showed good agreement for nine healthy subjects at four speeds. These results show that the algorithm reported here could constitute the basis of a robust, portable, low-cost system for ambulatory monitoring of gait.     

Temporal asymmetry as a gait quality indicator

A distinction is made between ‘diagnostic’ and ‘monitoring’ purposes for gait analysis. Two systems which use the temporal components of the walking cycle for the latter purpose are described. One is a laboratory-based system which derives a temporal asymmetry index combining the asymmetries of the swing and double-stance phases. The other is a gait monitor unit designed for clinical use which substitutes step asymmetry for the temporal asymmetry index and measures stride time as an indicator of general walking ability. Examples of the results obtained with both systems are given.     

Effects of postural threat on walking features of Parkinson's disease patients

This study investigated whether or not gait kinematics among healthy older individuals and Parkinson's disease (PD) patients are influenced by postural threat. Eight healthy older individuals and eight PD patients were examined while walking at self-selected velocities, under three conditions of postural threat: unconstrained floor; constrained floor (19 cm wide); constrained and elevated floor (19 cm wide by 10 cm high). Independent of the surface conditions, due to motor disturbances caused by the PD these patients walked slower, with shorter strides, and spent more time in the double support phase and less time in the swing phase than did their matched controls. Increases in postural threat resulted in altered gait kinematics for all subjects. Specifically, stride length, stride velocity, cadence, and heel contact velocity decreased, and stride duration and double support duration increased relative to increases in postural threat. All gait alterations were the result of participants’ attempts to facilitate locomotion control and maintain stability. The results of this study reveal that width and height constraints effectively perturbed the balance of all of the walking older individuals. The PD patients were able to modulate gait parameters when faced by a postural threat task.     

Impaired regulation of stride variability in Parkinson's disease subjects with freezing of gait

Patients with Parkinson's disease (PD) often experience freezing of gait, a debilitating phenomenon during which the subject suddenly becomes unable to start walking or to continue to move forward. Little is known about the gait of those subjects with PD who experience freezing of gait or the pathophysiology of freezing. One possibility is that freezing of gait is a truly paroxysmal phenomenon and that the usual walking pattern of subjects who experience freezing of gait is not different than that of other patients with PD who do not experience these transient episodes of freezing of gait. On the other hand, a recent study noted gait changes just prior to freezing and concluded that dyscontrol of the cadence of walking contributes to freezing. To address this question, we compared the gait of PD subjects with freezing of gait to PD subjects without freezing of gait. Given the potential importance of the dyscontrol of the cadence of walking in freezing, we focused on two aspects of gait dynamics: the average stride time (the inverse of cadence, a measure of the walking pace or rate) and the variability of the stride time (a measure of "dyscontrol," arrhythmicity and unsteadiness). We found that although the average stride time was similar in subjects with and without freezing, stride-to-stride variability was markedly increased among PD subjects with freezing of gait compared to those without freezing of gait, both while "on" (P<0.020) and "off" (P<0.002) anti-parkinsonian medications. Further, we found that increased gait variability was not related to other measures of motor control (while off medications) and levodopa apparently reduced gait variability, both in subjects with and without freezing. These results suggest that a paradigm shift should take place in our view of freezing of gait. PD subjects with freezing of gait have a continuous gait disturbance: the ability to regulate the stride-to-stride variations in gait timing and maintain a stable walking rhythm is markedly impaired in subjects with freezing of gait. In addition, these findings suggest that the inability to control cadence might play an important role in this debilitating phenomenon and highlight the key role of dopamine-mediated pathways in the stride-to-stride regulation of walking. Electronic Publication     

Startle responses in Parkinson patients during human gait

Falls frequently occur in patients with Parkinson’s disease (Bloem et al. 2001). One potential source for such falls during walking might be caused by the reaction to loud noises. In normal subjects startle reactions are well integrated in the locomotor activity (Nieuwenhuijzen et al. 2000), but whether this is also achieved in Parkinson patients is unknown. Therefore, in the present study, the startle response during walking was studied in eight patients with Parkinson’s disease and in eight healthy subjects. To examine how startle reactions are incorporated in an ongoing gait pattern of these patients, unexpected auditory stimuli were presented in six phases of the step cycle during walking on a treadmill. For both legs electromyographic activity was recorded from biceps femoris and tibialis anterior. In addition, we measured the stance and swing phases of both legs, along with the knee angles of both legs and the left ankle angle. In all subjects and all muscles, responses were detected. The pattern of the responses, latency, duration, and phase-dependent modulation was similar in both groups. However, the mean response amplitude was larger in patients due to a smaller habituation rate. No correlation was found between the degree of habituation and disease severity. Moreover, a decreased habituation was already observed in mildly affected patients, indicating that habituation of the startle response is a sensitive measure of Parkinson’s disease. The results complement the earlier findings of reduced habituation of blink responses in Parkinson’s disease. With respect to behavioral changes in healthy subjects we observed that startle stimuli induced a shortening of the step cycle and a decrease in range of motion. In the patient group, less shortening of the subsequent step cycle and no decrease in range of motion of the knee and ankle was seen. It is argued that the observed changes might contribute to the high incidence of falls in patients with Parkinson’s disease.Grants: This study was supported by an EU grant “Eurokinesis”.     

Quantitative video-based gait pattern analysis for hemiparkinsonian rats

Gait disturbances are common in the rat model of Parkinson's disease (PD) by administrating 6-hydroxydopamine. However, few studies have simultaneously assessed spatiotemporal gait indices and the kinematic information of PD rats during overground locomotion. This study utilized a simple, accurate, and reproducible method for quantifying the spatiotemporal and kinematic changes of gait patterns in hemiparkinsonian rats. A transparent walkway with a tilted mirror was set to capture underview footprints and lateral joint ankle images using a high-speed and high-resolution digital camera. The footprint images were semi-automatically processed with a threshold setting to identify the boundaries of soles and the critical points of each hindlimb for deriving the spatiotemporal and kinematic indices of gait. Following PD lesion, asymmetrical gait patterns including a significant decrease in the step/stride length and increases in the base of support and ankle joint angle were found. The increased footprint length, toe spread, and intermediary toe spread were found, indicating a compensatory gait pattern for impaired locomotor function. The temporal indices showed a significant decrease in the walking speed with increased durations of the stance/swing phase and double support time, which was more evident in the affected hindlimb. Furthermore, the ankle kinematic data showed that the joint angle decreased at the toe contact stage. We conclude that the proposed gait analysis method can be used to precisely detect locomotor function changes in PD rats, which is useful for objective assessments of investigating novel treatments for PD animal model.     

Postural instability and fall risk in Parkinson's disease: impaired dual tasking, pacing, and bilateral coordination of gait during the "ON" medication state

The interplay between gait and specific cognitive faculties, in particular executive function (EF) and dual tasking abilities, has been described in healthy adults and in patients with Parkinson??s disease (PD). There is, however, little direct evidence on the relationship between cognitive function, gait, and fall risk in PD, especially in the ??ON?? state (i.e., under the influence of the anti-parkinsonian medications). To address this issue, we evaluated cognitive function and gait under usual walking and dual-task conditions in 30 patients with PD in the ON state of the medication cycle. Subjects were classified as fallers or non-fallers based on their history. A computerized battery quantified cognitive function. Gait was assessed under three conditions: (1) Usual walking, (2) While subtracting serial 3?s, and (3) While subtracting serial 7?s. The EF and attention scores were lower in the fallers, compared to non-fallers (P????0.037), but general measures of cognition, e.g., memory, (P?=?0.341) were not. Gait speed, variability, and the bilateral coordination of gait were worse in the fallers in all conditions. The DT effects on gait variability and bilateral coordination were larger in the fallers (P?=?0.044, P?=?0.061, respectively). These results suggest that patients with PD who have a high risk of falling are more sensitive to DT effects, perhaps as a result of relatively poor EF. These cognitive and motor deficits may increase the likelihood of loss of balance during everyday attention-demanding tasks among patients with PD.     

Quantitative weightbearing and gait evaluation of paraplegics using functional electrical stimulation

In this study functional electrical stimulation (FES) was used to generate supported gait in paraplegic patients with traumatic upper-motor-neuron lesions, between the T5 and T12 spinal levels. Four patients have so far been treated and studied over a period of one year. The quadriceps and gluteus maximus muscles are stimulated simultaneously to achieve a supported standing position, while hip, knee and ankle flexions are achieved, alternately for each leg by stimulating the shank surface at two selected locations (flexion reflex). The stimulus used has an intensity of 120V, duration of 0·3 ms and frequency of 24 Hz. The standing and walking behaviour of patients was monitored in the gait laboratory of the Loewenstein Hospital. The amount of weightbearing on each foot during standing was established by time integration, over a standard period of time, of the reaction forces, as measured by ‘Kistler’ force platforms, on which the patient was required to stand, while taking care to support his walking aids outside the platform area. The gait of the patients was evaluated by means of an electrical contact system in which time/distance parameters of the stride were measured. Some typical results indicate a walking velocity of 10 cm s⁻¹ and weightbearing on the feet during standing of 80 per cent of body weight. Computer processing of the data acquired was used to obtain objective evaluation of the patients' progress during their training period towards easier and more independent mobility.     

Evidence for a common process in gait initiation and stepping on to a new level to reach gait velocity

The aim of this study was to examine the adaptability of the gait initiation process when confronted with stepping on (SO) to a new level. Eight young adults performed gait initiation at two different speed conditions in a level walking (LW) situation and in a SO situation aimed at walking on an elevated (16 cm) level surface. As in a previous study using a single step, we found in SO a contradiction between the characteristics of anticipatory postural adjustments (APA) and gait velocity, i.e. the peak of anteroposterior velocity of the body’s centre of gravity (CG) reached at the end of the first step. In normal and fast gaits, gait velocity was similar in both situations, whereas the duration and amplitude of the APA were smaller in SO than in LW. The reduction of APA in SO allowed the forward velocity of CG at the time of foot contact of the stepping limb to be lower than in LW. This is explained by the fact that the majority of body lift, beginning at this time, required a greater increase in forward velocity than in LW. Thus, with lower APA in SO, the gait velocity could be similar in both situations. From LW to SO, the spatio-temporal patterns in the forward velocity of CG varied within characteristic phases of the movement, but in a predictable way as gait velocity changed. These results gave evidence of an adaptation of the gait initiation process for the new constraints, despite the contradiction between APA and gait velocity. The spatio-temporal parameters of the anticipation phase in SO were pre-set according to the new requirements of the task: reaching gait velocity with a body lift. Furthermore, the time for reaching gait velocity was independent of both the amplitude of this velocity and the situation. This expressed the capacity of the subjects to use in SO the same optimal conditions to reach gait velocity as in LW, i.e. essentially in a ballistic manner.     

Modulation of lower limb withdrawal reflexes during gait: a topographical study

The aim of this study was to investigate the modulation and topography of the nociceptive withdrawal reflex elicited by painful electrical stimulation of the foot sole during gait. Fifteen healthy volunteers participated in this study. Cutaneous electrical stimulation was delivered on five locations of the foot sole after heel-contact, during foot-flat, after heel-off, and during the mid-swing phase of the gait cycle during treadmill walking. Reflexes were recorded from muscles of the ipsilateral and contralateral legs. Furthermore, the kinematic responses in the sagittal plane of the ipsilateral ankle, knee, and hip joints were recorded. Reflexes in the distal muscles showed a site-dependent modulation. The largest responses in tibialis anterior were evoked at the arch of the foot and the smallest at the heel (P < 0.05). The largest soleus responses were also elicited at the arch of the foot (P < 0.04). The EMG responses in flexors and extensors of the knee and extensors of the contralateral leg were generally not dependent on the stimulation site. The response at the three joints showed site dependency, especially during the swing phase where maximal flexion was obtained by stimulation at the arch of the foot (P < 0.05). The withdrawal reflex was modulated during the gait cycle and presented distinctive characteristics for the different muscles studied. Minimal kinematic responses were observed during stance in contrast to swing phase. Modulation of the reflex probably ensures an appropriate withdrawal but primarily secures balance and continuity of movement.     

Ageing effects on knee and ankle joint angles at key events and phases of the gait cycle

The objective of this research was to determine whether joint angles at critical gait events and during major energy generation/absorption phases of the gait cycle would reliably discriminate age-related degeneration during unobstructed walking. The gaits of 24 healthy adults (12 young and 12 elderly) were analysed using the PEAK Motus motion analysis system. The elderly participants showed significantly greater single (60.3% versus 62.3%, p < 0.01) and double ( p < 0.05) support times, reduced knee flexion (47.7 degrees versus 43.0 degrees , p < 0.05) and ankle plantarflexion (16.8 degrees compared to 3.3 degrees , p = 0.053) at toe off, reduced knee flexion during push-off and reduced ankle dorsiflexion (16.8 degrees compared to 22.0 degrees , p < 0.05) during the swing phase. The plantarflexing ankle joint motion during the stance to swing phase transition (A2) for the young group (31.3 degrees ) was about twice ( p < 0.05) that of the elderly (16.9 degrees ). Reduced knee extension range of motion suggests that the elderly favoured a flexed-knee gait to assist in weight acceptance. Reduced dorsiflexion by the elderly in the swing phase implies greater risk of toe contact with obstacles. Overall, the results suggest that joint angle measures at critical events/phases in the gait cycle provide a useful indication of age-related degeneration in the control of lower limb trajectories during unobstructed walking.     

Gait asymmetry in patients with Parkinson’s disease and elderly fallers: when does the bilateral coordination of gait require attention?

While it is known that certain pathologies may impact on left-right symmetry of gait, little is known about the mechanisms that contribute to gait symmetry or how high in the hierarchy of the control of gait symmetry is regulated in humans. To assess the contribution of cognitive function to gait symmetry, we measured gait asymmetry (GA) in three subject groups, patients with Parkinson's disease (PD, n = 21), idiopathic elderly fallers (n = 15), and healthy elderly controls (n = 11). All subjects walked, under two walking conditions: usual walking and dual tasking (cognitive loading) condition. For each subject, the swing time (SW) was calculated and averaged across strides for the left and right feet (SWL and SWR). GA was defined as: 100 x /ln(SWR/SWL)/. For both the PD patients and the elderly fallers GA values were significantly higher during the usual walking condition, as compared with the control group (P < 0.01). In addition, for both the PD patients and the elderly fallers, GA significantly increased when they walked and performed a dual task, compared with the usual walking condition (P < 0.003). In contrast, dual tasking did not affect the GA of the healthy controls (P = 0.518). GA was associated with gait speed and gait variability, but no correlations were found between GA and the asymmetry of the classic PD motor symptoms. Thus, the results suggest that the ability to generate a steady, rhythmic walk with a bilaterally coordinated gait does not rely heavily on mental attention and cognitive resources in healthy older adults. In contrast, however, when gait becomes impaired and less automatic, GA apparently relies on cognitive input and attention.     

截瘫步行器的仿生效果

背景：截瘫步行器的临床应用,使截瘫患者重建步行功能成为可能,但截瘫步行器只为进行步行康复训练及简单的行走,距离真正意义上的步行功能代偿相差还很远。 目的：对目前几种截瘫步行器的结构特点、作用机制及仿生效果进行归纳、分析。 方法：应用计算机检索1990-01/2008-12 PubMed数据库及万方数据库有关截瘫步行器的特点、仿生效果及临床应用方面的相关文献,英文检索词“reciprocation gait orthosis,walkabout,bionice”,中文检索词“截瘫步行器,仿生”。检索文献量总计32篇。 结果与结论：目前无动力截瘫步行器运用较广泛,但对截瘫患者来说,通常只为进行步行康复训练及简单的行走,距离真正意义上的步行功能代偿相差还很远。运用最广的往复式截瘫步行器和互动截瘫步行器这两种截瘫步行器仿生效果较差,步态严重失真,体能消耗大,而由外部能源补充能耗的步行器则可以克服无动力步行器的不足,随着人工智能技术在机器人和许多工业领域得到了广泛应用,它的发展可为患者提供性能优良,安全可靠,更具有仿生性的截瘫步行器产品。     

Trans-radial upper extremity amputees are capable of adapting to a novel dynamic environment

This study has focused on how sensory stimulation affects gait in Parkinson’s disease (PD). The kinematic parameters of gait [cadence, step amplitude, velocity, coefficient of variation of stride time (CV_stride-time), and the coefficient of variation of the step amplitude (CV_{step-amplitude})] were analysed in 25 PD patients and 10 control subjects. Step amplitude, velocity and CV_stride-time were altered in the patients with PD. However, when kinematic parameters were analysed as a function of disease severity, none of the parameters differed between early PD (I–II Hoehn and Yahr) and the controls. Nevertheless, more severely affected PD patients (III–IV Hoehn and Yahr) walked with a reduced step amplitude, lower velocity, higher CV_stride-time, and higher CV_{step-amplitude} than the controls. The administration of auditory stimulation at a frequency matching the preferred walking cadence led to a decrease in the CV_stride-time in PD_III–IV patients, and to an increase in step amplitude in PD_III–IV and controls. Visual stimulation at the same frequency did not modify any of the altered kinematic parameters in PD_III–IV patients. When different stimulation frequencies were utilised, auditory stimulation significantly changed some of the altered walking parameters in Parkinson patients. Frequencies matching preferred walking cadence or above this, up to the fastest walking, were those that seem to interact most effectively with the abnormal kinematic parameters in PD_III–IV patients. Visual stimulation negatively modulated cadence in PD_III–IV in the frequency range used. Sensory stimulation facilitates gait in PD. Studies using sensory stimulation as a tool to facilitate walking should take into account the grade of disability of the patients.     

Effect of a textured insole on balance and gait symmetry

Asymmetry of standing balance and gait is common in individuals with neurological disorders, and achieving symmetrical stance and gait is an important goal of rehabilitation. The purpose of this study was to investigate the effect of a novel discomfort-induced approach (that is based on using a single textured insole) on the alteration in the symmetry of gait and balance. Eleven healthy subjects (6 females and 5 males, mean age of 28.0 ± 4.1 years) were tested using the Computerized Dynamic Posturography and GaitRite systems when standing or walking while wearing standard footwear with the textured insole positioned either in the left or in the right shoe, and without the insole. Significant immediate effect of the textured insole was seen in the outcome measures of static (weight bearing) and dynamic (weight symmetry index, strength symmetry) balance tests (p < 0.05) as well as in gait symmetry (single support and swing phases) (p < 0.05). The results of the study indicate that a textured insole can significantly modify the symmetry of stance and gait in healthy individuals. Pilot data from individuals with stroke also showed a reduction in the asymmetry of gait when walking with the single textured insole in the shoe on the unaffected side. This outcome provides support for future studies on the efficacy of the textured insole in minimizing asymmetry of gait and posture in individuals in need.     

基于非线性时间序列法研究人体步行稳定性

目的应用非线性时间序列分析方法,研究健康老年与青年志愿者的步行稳定性,为更全面评估人体的动态平衡、预测跌倒风险提供重要依据。方法应用VICON运动捕捉系统,采集肌骨系统健康志愿者(7名老年和10名青年)在不同步速(80%、100%1、20%自然步速)下的运动学数据,提取志愿者在30个连续步态周期中,第7颈椎和第10胸椎在前后和左右方向上的位移,以及下肢各关节屈曲伸展和外展内收运动角度,计算位移和运动角度变化的最大Lyapunov指数,比较分析老年与青年组之间步行稳定性差异,以及步速对人体步行稳定性影响。结果青年组步行稳定性优于老年组,并在某些运动节段呈现显著性差异(P<0.01);老年和青年的步行稳定性随步速增加而降低(P<0.05)。结论应用非线性时间序列分析方法中的最大Lyapunov指数,能有效并定量地评测人体步行中各运动节段的稳定性。