Exploring gait adaptations to perturbed and conventional treadmill training in Parkinson’s disease: Time-course,sustainability, and transfer

BackgroundGait impairment is a major motor symptom in Parkinson’s disease (PD), and treadmill training is an effective non-pharmacological treatment option.Research questionIn this study, the time course, sustainability and transferability of gait adaptations to treadmill training with and without additional postural perturbations were investigated.Methods38 PD patients (Hoehn & Yahr 1–3.5) were randomly allocated to eight weeks of treadmill training, performed twice-weekly for 40 min either with (perturbation treadmill training [PTT], n = 18) or without (conventional treadmill training [CTT], n = 20) additional perturbations to the treadmill surface. Spatiotemporal gait parameters were assessed during treadmill walking on a weekly basis (T0–T8), and after three months follow-up (T9). Additional overground gait analyses were performed at T0 and T8 to investigate transfer effects.ResultsTreadmill gait variability reduced linearly over the course of 8 weeks in both groups (p < .001; Cohen’s d (range): −0.53 to −0.84). Only the PTT group significantly improved in other gait parameters (stride length/time, stance-/swing time), with stride time showing a significant between-group interaction effect (Cohen’s d = 0.33; p = .05). Additional between-group interactions indicated more sustained improvements in stance (Cohen’s d = 0.85; p = .02) and swing time variability in the PTT group (Cohen’s d = 0.82; p = .03) at T9. Overground gait improvements at T8 existed only in stance (d = -0.73; p = .04) and swing time (d = 0.73; p = .04).DiscussionTreadmill stride-to-stride variability reduced substantially and linearly, but transfer to overground walking was limited. Adding postural perturbations tended to increase efficacy and sustainability of several gait parameters. However, since between-group effects were small, more work is necessary to support these findings.     

Biomechanical analysis of gait termination in 11–17 year old youth at preferred and fast walking speeds

In populations where walking and/or stopping can be difficult, such as in children with cerebral palsy, the ability to quickly stop walking may be beyond the child’s capabilities. Gait termination may be improved with physical therapy. However, without a greater understanding of the mechanical requirements of this skill, treatment planning is difficult. The purpose of this study was to understand how healthy children successfully terminate gait in one step when walking quickly, which can be challenging even for healthy children. Lower extremity kinematic and kinetic data were collected from 15 youth as they performed walking, planned, and unplanned stopping tasks. Each stopping task was performed as the subject walked at his/her preferred speed and a fast speed. The most significant changes in mechanics between speed conditions (preferred and fast) of the same stopping task were greater knee flexion angles (unplanned: +16.49 ± 0.54°, p = 0.00; planned: +15.75 ± 1.1°, p = 0.00) and knee extension moments (unplanned: +0.67 ± 0.02 N/kgm, p = 0.00; planned: +0.57 ± 0.23 N/kgm, p = 0.00) at faster speeds. The extra range of motion in the joints and extra muscle strength required to maintain the stopping position suggests that stretching and strengthening the muscles surrounding the joints of the lower extremity, particularly the knee, may be a useful intervention.     

The influence of aging on the spatial and temporal variables of gait during usual and fast speeds in older adults aged 60 to 102 years

BackgroundWith increases in life expectancy, it is important to understand the influence of aging on gait, given that this activity is related to the independence of older adults and may help in the development of health strategies that encourage successful aging in all phases of this process.Research questionTo compare gait parameters with usual and fast speeds for independent and autonomous older adults throughout the aging process (60 to 102 years old), and also to identify which of the gait variables are best for identifying differences across the different age groups.MethodsTwo hundred older adults aged between 60 and 102 years were evaluated. The sample was divided into 3 age groups: 60 to 79 years, 80 to 89 years and 90 years and over. The analyzed gait variables were: speed (meters/s), cadence (steps/min), stride time (seconds), step length (centimeters), double support (percentage of the gait cycle), swing (percentage of the gait cycle), step length variability (CoV%) and stride time variability (CoV%).ResultsGroup comparison regarding usual gait and fast gait revealed a significant difference in all gait variables. In addition, it can be seen that variables such as gait speed and step length showed greater effect sizes in intergroup comparison (usual gait: 0.48 and 0.47; fast gait: 0.36 and 0.40; respectively), possibly showing that these variables can better detect the changes observed with increasing age.ConclusionThere are differences in the gait performance of older adults from different age groups for usual and fast gait speeds, which is more evident regarding gait speed and step length variables. We recommend the use of usual gait for the identification of the effects of aging because, besides showing a higher effect size values it is more comfortable and requires less effort from older subjects.     

Profiling movement quality and gait characteristics according to body-mass index in children (9–11 y)

Obese children move less and with greater difficulty than their normal-weight counterparts. Whilst the effect of high BMI on cardiovascular fitness is well known, the effect on movement quality characteristics during a standardised fitness test has not been investigated. The aims of this study were, to characterise the movement quality of children performing the multi-stage fitness test (MSFT), and, report how movement quality characteristics cluster according to weight status. One hundred and three children (10.3 ± 0.6 y, 1.42 ± 0.08 m, 37.8 ± 9.3 kg, BMI; 18.5 ± 3.3 kg m²) performed the MSFT whilst wearing an ankle mounted accelerometer. BMI groups were used to classify children as underweight (UW), normal weight (NW), overweight (OW) and obese (OB). Characteristics of movement were profiled using a clustering algorithm. Spearman’s rho was used to assess relationship with BMI group, and a Mann-Whitney U test was used to assess differences between BMI groups. Obese children had significantly lower spectral purity than every other group and significantly lower time to exhaustion (TTE) than UW and NW children (P < 0.05). BMI was clustered with stride profile and TTE with spectral purity. Significant negative correlations (P < 0.05) were found between BMI and TTE (r = −0.25), spectral purity (r = −0.24), integrated acceleration (r = −0.22), stride angle (r = −0.23) and stride variability (r = −0.22). This was the first study to report the spectral purity of children’s gait. Further analysis unveiled key performance characteristics that differed between BMI groups. These were (i) representative of children’s performance during the MSFT and, (ii) significantly negatively correlated with BMI.     

How does the heel-off posture modify gait initiation parameter programming?

The authors studied the adjustment of the 2 distinct known expressions of gait velocity, the velocity of the center of gravity (CG) and the velocity of the center of foot pressure (CP) at the end of the 1st step in 2 experimental situations: natural gait initiation (the control situation, CS) and heel-off gait initiation (the test situation, TS). Gait was initiated by 7 healthy participants, from an erect spontaneous posture in the CS and from a posture with heels raised in the TS, on a force platform at 3 self-selected speed conditions. Biomechanical data from the force platform were collected in both experimental situations, and the authors used a particular gait analysis based on the differential method of Y. Brenière (2003) in order to approach velocity modulation by means of step length and frequency. Results showed that CG and CP velocities were adjusted differently during heel-off gait initiation than during natural gait initiation. CP velocity, as compared with CG velocity, was overestimated in TS. Results also established the relevance of the expression of step velocity by means of step length and frequency: The central nervous system, taking into account the specific postural constraints of each experimental situation, uses a reference value and a regulating parameter to modulate step velocity. Moreover, the contributions of 1st step length and frequency to the expression of step velocity in TS and CS were different. Thus, a specific locomotor behavior corresponds to a given experimental situation that is characterized by its own initial biomechanical constraints.     

Listenmee® and Listenmee® smartphone application: Synchronizing walking to rhythmic auditory cues to improve gait in Parkinson’s disease

Evidence supports the use of rhythmic external auditory signals to improve gait in PD patients (Arias & Cudeiro, 2008; Kenyon & Thaut, 2000; McIntosh, Rice & Thaut, 1994; McIntosh et al., 1997; Morris, Iansek, & Matyas, 1994; Thaut, McIntosh, & Rice, 1997; Suteerawattananon, Morris, Etnyre, Jankovic, & Protas , 2004; Willems, Nieuwboer, Chavert, & Desloovere, 2006). However, few prototypes are available for daily use, and to our knowledge, none utilize a smartphone application allowing individualized sounds and cadence. Therefore, we analyzed the effects on gait of Listenmee®, an intelligent glasses system with a portable auditory device, and present its smartphone application, the Listenmee app®, offering over 100 different sounds and an adjustable metronome to individualize the cueing rate as well as its smartwatch with accelerometer to detect magnitude and direction of the proper acceleration, track calorie count, sleep patterns, steps count and daily distances. The present study included patients with idiopathic PD presented gait disturbances including freezing. Auditory rhythmic cues were delivered through Listenmee®. Performance was analyzed in a motion and gait analysis laboratory. The results revealed significant improvements in gait performance over three major dependent variables: walking speed in 38.1%, cadence in 28.1% and stride length in 44.5%. Our findings suggest that auditory cueing through Listenmee® may significantly enhance gait performance. Further studies are needed to elucidate the potential role and maximize the benefits of these portable devices.     

Development of temporal and spatial characteristics of anticipatory postural adjustments during gait initiation in children aged 3–10 years

This study aimed to analyze the development of direction specificities of temporal and spatial control and the coordination pattern of anticipatory postural adjustment (APA) along the anteroposterior (AP) and mediolateral (ML) directions during gait initiation (GI) in children aged 3–10 years. This study included 72 healthy children aged 3–10 years and 14 young adults. The child population was divided into four groups by age: 3–4, 5–6, 7–8, and 9–10 years. The GI task included GI using the dominant limb. The peak center of feet pressure (COP) shifts during APAs (APA_peak), initiation time of COP shifts (APA_onset), and the COP vectors in the horizontal plane were calculated to evaluate the direction specificity of spatial, temporal, and coordination control, respectively. A difference in direction specificity development was found for the APA_peak. The APA_peak in the mediolateral axis, but not in the anteroposterior axis, was significantly higher in the 7–8 years age group than in other groups. Although APA_onset was not found for direction specificity, a significant difference between the adult and children groups (5–6 years, 7–8 years, and 9–10 years) was observed in the direction of the COP vector. In conclusion, the developmental process of the spatial, temporal, and coordination control of APAs during GI varied with age. Furthermore, the spatial control and coordination pattern of APAs was found to be direction specific. All components of APAs, namely temporal and spatial control, coordination pattern, and direction specificities, should be analyzed to capture the developmental process of anticipatory postural control.     

Emotional state affects gait initiation in individuals with Parkinson’s disease

The purpose of the present study was to determine the impact of manipulating emotional state on gait initiation in persons with Parkinson’s disease (PD) and healthy older adults. Following the presentation of pictures that are known to elicit specific emotional responses, participants initiated gait and continued to walk for several steps at their normal pace. Reaction time, the displacement and velocity of the center of pressure (COP) trajectory during the preparatory postural adjustments, and length and velocity of the first two steps were measured. Analysis of the gait initiation measures revealed that exposure to (1) threatening pictures, relative to all other pictures, speeded the initiation of gait for PD patients and healthy older adults; (2) approach-oriented emotional pictures (erotic and happy people), relative to withdrawal-oriented pictures, facilitated the anticipatory postural adjustments of gait initiation for PD patients and healthy older adults, as evidenced by greater displacement and velocity of the COP movement; and (3) emotional pictures modulated gait initiation parameters in PD patients to the same degree as in healthy older adults. Collectively, these findings hold significant implications for understanding the circuitry underlying the manner by which emotions modulate movement and for the development of emotion-based interventions designed to maximize improvements in gait initiation for individuals with PD.     

“Posture first”: Interaction between posture and locomotion in people with low back pain during unexpectedly cued modification of gait initiation motor command

The ability to adapt anticipatory postural adjustments (APAs) in response to perturbations during single-joint movements is altered in people with chronic low back pain (LBP), but a comprehensive analysis during functional motor tasks is still missing. This study aimed to compare APAs and stepping characteristics during gait initiation between people with LBP and healthy controls, both in normal (without cue occurrence) condition and when an unexpected visual cue required to switch the stepping limb. Fourteen individuals with LPB and 10 healthy controls performed gait initiation in normal and switch conditions. The postural responses were evaluated through the analysis of center of pressure, propulsive ground reaction forces, trunk and whole-body kinematics, and activation onsets of leg and back muscles. During normal gait initiation, participants with LBP exhibited similar APAs and stepping characteristics to healthy controls. In the switch condition, individuals with LBP were characterized by greater mediolateral postural stability but decreased forward body motion and propulsion before stepping. The thorax motion was associated with forward propulsion parameters in both task conditions in people with LBP but not healthy controls. No between-group differences were found in muscle activation onsets. The results suggest that postural stability is prioritized over forward locomotion in individuals with LBP. Furthermore, the condition-invariant coupling between thorax and whole-body forward propulsion in LBP suggests an adaptation in the functional use of the thorax within the postural strategy, even in poor balance conditions.     

Are transitions in human gait determined by mechanical,kinetic or energetic factors?

It is currently unclear whether it is the need to maintain metabolic efficiency, the need to keep skeletal loading below critical force levels, or simple mechanical factors that drive the walk-to-run (W-R) and run-to-walk (R-W) transitions in human gait. Eighteen adults (9 males and 9 females) locomoted on an instrumented treadmill using their preferred gait. Each completed 2 ascending (W-R) and 2 descending (R-W) series of trials under three levels of loading (0%, 15% and 30% body weight). For each trial, participants locomoted for 60 s at each of 9 different speeds--4 speeds both above and below their preferred transition speed (PTS) plus their PTS. Evidence was sought for critical levels of key kinetic (maximum vertical force, impulse, first peak force, time to first peak force and maximum loading rate), energetic (oxygen consumption, transport cost) and mechanical variables (limb lengths, strength) predictive of the gait transition. Analyses suggested the kinetic variables of time to first peak force and loading rate as the most likely determinants of the W-R and R-W transitions.     

Are there common walking gait characteristics in patients diagnosed with late-onset Pompe disease?

Late-onset Pompe disease (LOPD) is a rare disease, defined as a progressive accumulation of lysosomal glycogen resulting in muscle weakness and respiratory problems. Anecdotally, individuals often have difficulties walking, yet, there is no three-dimensional data supporting these claims. We aimed to assess walking patterns in individuals with LOPD and compare with healthy individuals. Kinematic, kinetic and spatiotemporal data were compared during walking at a self-selected speed between individuals with LOPD (n = 12) and healthy controls (n = 12). Gait profile scores and movement analysis profiles were also determined to indicate gait quality. In comparison with healthy individuals, the LOPD group demonstrated greater thoracic sway (96%), hip adduction angles (56%) and pelvic range of motion (77%) and reduced hip extensor moments (36%). Greater group variance for the LOPD group were also observed. Individuals with LOPD had a slower (15%) walking speed and reduced cadence (7%). Gait profile scores were 37% greater in the LOPD group compared to the healthy group. Proximal muscular weakness associated with LOPD disease is likely to have resulted in a myopathic gait pattern, slower selected walking speeds and deviations in gait patterns. Although individuals with LOPD presented with some common characteristics, greater variability in gait patterns is likely to be a result of wide variability in phenotype spectrum observed with LOPD. This is the first study to examine walking in individuals with LOPD using instrumented gait analysis and provides an understanding of LOPD on walking function which can help orientate physiotherapy treatment for individuals with LOPD.     

Auditory event perception: The source—perception loop for posture in human gait

There is a small but growing literature on the perception of natural acoustic events, but few attempts have been made to investigate complex sounds not systematically controlled within a laboratory setting. The present study investigates listeners’ ability to make judgments about the posture (upright—stooped) of the walker who generated acoustic stimuli contrasted on each trial. We use a comprehensive three-stage approach to event perception, in which we develop a solid understanding of the source event and its sound properties, as well as the relationships between these two event stages. Developing this understanding helps both to identify the limitations of common statistical procedures and to develop effective new procedures for investigating not only the two information stages above, but also the decision strategies employed by listeners in making source judgments from sound. The result is a comprehensive, ultimately logical, but not necessarily expected picture of both the source—sound—perception loop and the utility of alternative research tools.     

How is gait visually regulated when the head is travelling faster than the legs?

Gait regulation patterns were examined under various visual conditions in order to determine whether speed information provided by peripheral vision is taken into account in gait adjustments. Nine subjects walking toward a visual target on the ground were required to place one foot exactly on it. peripheral vision was either restricted to a 12 degrees angle or decorrelated, corresponding to a moving speed greater than the actual walking speed. Decorrelation was obtained by placing the subject on a treadmill moving in the walking direction. The results show, by comparison with the control condition, that the restriction of peripheral visual information did not affect the accuracy of the foot positioning, whereas decorrelated conditions affected it significantly: we noted that the gait regulation was triggered early on and showed a very stable pattern so that the distance to the target was consistently underestimated. This suggest that, although visual speed information is not indispensable in this kind of task, it is nevertheless taken into account in stride adjustments when the whole visual field is available. The results are discussed, in the context of a time-based approach to locomotor activity, in relation to the possible visual methods that might be used in obtaining information about time to contact the target.     

Dual-task-related gait changes in the elderly: does the type of cognitive task matter?

Dual-task-related gait changes among older adults while they perform spoken verbal tasks have been reported frequently. The authors examined whether the type of walking-associated spoken verbal task matters for dual-task-related gait changes in 16 older adults classified as transitionally frail. Mean stride time increased significantly when they walked and performed an arithmetic or a verbal fluency task compared with when they only walked (p < .001), whereas the coefficients of variation increased significantly only when they walked and performed the arithmetic task (p = .005) but not the verbal fluency task (p = .134). Those findings suggest that stride time variability under a dual-task condition depends on the type of walking-associated spoken verbal task.     

What factors determine the preferred gait transition speed in humans? A review of the triggering mechanisms

Human locomotion is a fundamental skill that is required for daily living, yet it is not completely known how human gait is regulated in a manner that seems so effortless. Gait transitions have been analyzed to gain insight into the control mechanisms of human locomotion since there is a known change that occurs as the speed of locomotion changes. Specifically, as gait speed changes, there is a spontaneous transition between walking and running that occurs at a particular speed. Despite the growing body of research on the determinants of this preferred transition speed and thus the triggering mechanisms of human gait transitions, a clear consensus regarding the control mechanisms of gait is still lacking. Therefore, this article reviews the determinants of the preferred transition speed using concepts of the dynamic systems theory and how these determinants contribute to four proposed triggers (i.e. metabolic efficiency, mechanical efficiency, mechanical load and cognitive and perceptual) of human gait transitions. While individual anthropometric and strength characteristics influence the preferred transition speed, they do not act to trigger a gait transition. The research has more strongly supported the mechanical efficiency and mechanical load determinants as triggering mechanisms of human gait transitions. These mechanical determinants, combined with cognitive and perceptual processes may thus be used to regulate human gait patterns through proprioceptive and perceptual feedback as the speed of locomotion changes.     

Motor planning in Parkinson’s disease patients experiencing freezing of gait: The influence of cognitive load when approaching obstacles

Freezing of gait (FOG) in Parkinson’s disease (PD) is typically assumed to be a pure motor deficit, although it is important to consider how an abrupt loss of gait automaticity might be associated with an overloaded central resource capacity. If resource capacity limits are a factor underlying FOG, then obstacle crossing may be particularly sensitive to dual task effects in eliciting FOG. Participants performed a dual task (auditory digit monitoring) in order to increase cognitive load during obstacle crossing. Forty-two non-demented participants (14 PD patients with FOG, 13 PD who do not freeze, and 14 age-matched healthy control participants) were required to walk and step over a horizontal obstacle set at 15% of the participants’ height. Kinematic data were split into two phases of their approach: early (farthest away from the obstacle), and late (just prior to the obstacle). Interestingly, step length variability and step time variability increased when PD patients with FOG performed the dual task, but only in the late phase prior to the obstacle (i.e. when closest to the obstacle). Additionally, immediately after crossing, freezers landed the lead foot abnormally close to the obstacle regardless of dual task condition, and also contacted the obstacle more frequently (planning errors). Strength of the dual task effect was associated with low general cognitive status, declined executive function, and inappropriate spatial planning, but only in the PD-FOG group. This study is the first to demonstrate that cognitive load differentially impacts planning of the final steps needed to avoid an obstacle in PD patients with freezing, but not non-freezers or healthy controls, suggesting specific neural networks associated with FOG behaviours.     

Effects of gait speed on the body’s center of mass motion relative to the center of pressure during over-ground walking

Preferred walking speed (PWS) reflects the integrated performance of the relevant physiological sub-systems, including energy expenditure. It remains unclear whether the PWS during over-ground walking is chosen to optimize one’s balance control because studies on the effects of speed on the body’s balance control have been limited. The current study aimed to bridge the gap by quantifying the effects of the walking speed on the body’s center of mass (COM) motion relative to the center of pressure (COP) in terms of the changes and directness of the COM-COP inclination angle (IA) and its rate of change (RCIA). Data of the COM and COP were measured from fifteen young healthy males at three walking speeds including PWS using a motion capture system. The values of IAs and RCIAs at key gait events and their average values over gait phases were compared between speeds using one-way repeated measures ANOVA. With increasing walking speed, most of the IA and RCIA related variables were significantly increased (p < 0.05) but not for those of the frontal IA. Significant quadratic trends (p < 0.05) with highest directness at PWS were found in IA during single-limb support, and in RCIA during single-limb and double-limb support. The results suggest that walking at PWS corresponded to the COM-COP control maximizing the directness of the RCIAs over the gait cycle, a compromise between the effects of walking speed and the speed of weight transfer. The data of IA and RCIA at PWS may be used in future assessment of balance control ability in people with different levels of balance impairments.     

Disability and employment – overview and highlights

Due to the expected decline in the working-age population, especially in European countries, people with disabilities are now more often recognized as a valuable resource in the workforce and research into disability and employment is more important than ever. This paper outlines the state of affairs of research on disability and employment. We thereby focus on one particular group of people with disabilities, that is to say people with mental disabilities. We define disability according to the International Classification of Functioning, Disability and Health (ICF) of the World Health Organization, by that recognizing that disability results from the interaction of person and environment. Key issues, including the complexity of defining disability, the legal situation in Europe and North America concerning disability at work, and barriers and enablers to employment, are discussed. For each of the topics we show important findings in the existing literature and indicate where more in-depth research is needed. We finalize with a concrete research agenda on disability and employment and provide recommendations for practice.