Long-term Effect of Regular Physical Activity and Exercise Habits in Patients With Early Parkinson Disease

Objective:Owing to the lack of long-term observations and/or comprehensive adjustment for confounding factors, reliable conclusions regarding long-term effects of exercise and regular physical activity in Parkinson’s disease (PD) have yet to be drawn. Here, using data from the Parkinson’s Progression Markers Initiative study that includes longitudinal and comprehensive evaluations of many clinical parameters, we examined the long-term effects of regular physical activity and exercise habits on the course of PD.Methods:In this observational cohort study, we primarily used the multivariate linear mixed-effects models to analyze the interaction effects of their regular physical activity and moderate-to-vigorous exercise levels, measured through the Physical Activity Scale for the Elderly questionnaire, on the progression of clinical parameters, after adjusting for age, sex, levodopa-equivalent dose, and disease duration. We also calculated bootstrapping 95% confidence intervals (CIs), and conducted sensitivity analyses using the multiple imputation method and subgroup analyses using the propensity score matching to match for all baseline background factors.Results:237 early PD patients [median (interquartile range); age, 63.0 (56.0–70.0) years; Male, 69.2%; follow-up duration, 5.0 (4.0–6.0) years] were included. Regular physical activity and moderate-to-vigorous exercise levels at the baseline did not significantly affect the subsequent clinical progression of PD. However, average regular overall physical activity levels over time were significantly associated with slower deterioration of postural and gait stability [standardized fixed-effects coefficients of the interaction term (βinteraction) = -0.10 (95% CI, -0.14 to -0.06)], activities of daily living [βinteraction = 0.08 (95% CI, 0.04 to 0.12)], and processing speed [βinteraction = 0.05 (95% CI, 0.03 to 0.08)] in PD patients. Moderate-to-vigorous exercise levels were preferentially associated with slower decline of postural and gait stability [βinteraction = -0.09 (95% CI, -0.13 to -0.05)] and work-related activity levels were primarily associated with slower deterioration of processing speed [βinteraction = 0.07 (95% CI, 0.04 to 0.09)]. Multiple imputation and propensity score matching confirmed the robustness of our results.Conclusions:In the long-term, the maintenance of high regular physical activity levels and exercise habits was robustly associated with better clinical course of PD, with each type of physical activity having different effects.Trial Registration Information:Clinicaltrials.gov (NCT01176565). A link to trial registry page is https://clinicaltrials.gov/ct2/show/NCT01141023.Classification of Evidence:This study provides Class II evidence that sustained increase in overall regular physical activity levels in patients with early Parkinson disease was associated with slower decline of several clinical parameters.

Split-Belt Training but Not Cerebellar Anodal tDCS Improves Stability Control and Reduces Risk of Fall in Patients with Multiple Sclerosis

The objective of this study was to examine the therapeutic potential of multiple sessions of training on a split-belt treadmill (SBT) combined with cerebellar anodal transcranial direct current stimulation (tDCS) on gait and balance in People with Multiple Sclerosis (PwMS). Twenty-two PwMS received six sessions of anodal (PwMSreal, n = 12) or sham (PwMSsham, n = 10) tDCS to the cerebellum prior to performing the locomotor adaptation task on the SBT. To evaluate the effect of the intervention, functional gait assessment (FGA) scores and distance walked in 2 min (2MWT) were measured at the baseline (T0), day 6 (T5), and at the 4-week follow up (T6). Locomotor performance and changes of motor outcomes were similar in PwMSreal and PwMSsham independently from tDCS mode applied to the cerebellum (anodal vs. sham, on FGA, p = 0.23; and 2MWT, p = 0.49). When the data were pooled across the groups to investigate the effects of multiple sessions of SBT training alone, significant improvement of gait and balance was found on T5 and T6, respectively, relative to baseline (FGA, p < 0.001 for both time points). The FGA change at T6 was significantly higher than at T5 (p = 0.01) underlining a long-lasting improvement. An improvement of the distance walked during the 2MWT was also observed on T5 and T6 relative to T0 (p = 0.002). Multiple sessions of SBT training resulted in a lasting improvement of gait stability and endurance, thus potentially reducing the risk of fall as measured by FGA and 2MWT. Application of cerebellar tDCS during SBT walking had no additional effect on locomotor outcomes.

Control of Thruster-Assisted, Bipedal Legged Locomotion of the Harpy Robot

Fast constraint satisfaction, frontal dynamics stabilization, and avoiding fallovers in dynamic, bipedal walkers can be pretty challenging. The challenges include underactuation, vulnerability to external perturbations, and high computational complexity that arise when accounting for the system full-dynamics and environmental interactions. In this work, we study the potential roles of thrusters in addressing some of these locomotion challenges in bipedal robotics. We will introduce a thruster-assisted bipedal robot called Harpy. We will capitalize on Harpy’s unique design to propose an optimization-free approach to satisfy gait feasibility conditions. In this thruster-assisted legged locomotion, the reference trajectories can be manipulated to fulfill constraints brought on by ground contact and those prescribed for states and inputs. Unintended changes to the trajectories, especially those optimized to produce periodic orbits, can adversely affect gait stability and hybrid invariance. We will show our approach can still guarantee stability and hybrid invariance of the gaits by employing the thrusters in Harpy. We will also show that the thrusters can be leveraged to robustify the gaits by dodging fallovers or jumping over large obstacles.

Small Directional Treadmill Perturbations Induce Differential Gait Stability Adaptation

Introducing unexpected perturbations to challenge gait stability is an effective approach to investigate balance control strategies. Little is known about the extent to which people can respond to small perturbations during walking. This study aimed to determine how subjects adapted gait stability to multidirectional perturbations with small magnitudes applied on a stride-by-stride basis. Ten healthy young subjects walked on a treadmill that either briefly decelerated belt speed ("stick"), accelerated belt speed ("slip"), or shifted the platform medial-laterally at right leg mid-stance. We quantified gait stability adaptation in both anterior-posterior and medial-lateral directions using margin of stability and its components, base of support and extrapolated center of mass. Gait stability was disrupted upon initially experiencing the small perturbations as margin of stability decreased in the stick, slip, and medial shift perturbations and increased in the lateral shift perturbation. Gait stability metrics were generally disrupted more for perturbations in the coincident direction. Subjects employed both feedback and feedforward strategies in response to the small perturbations, but mostly used feedback strategies during adaptation. Subjects primarily used base of support (foot placement) control in the lateral shift perturbation and extrapolated center of mass control in the slip and medial shift perturbations. These findings provide new knowledge about the extent of gait stability adaptation to small magnitude perturbations applied on a stride-by-stride basis and reveal potential new approaches for balance training interventions to target foot placement and center of mass control.

Differences in Gait Stability and Acceleration Characteristics Between Healthy Young and Older Females

Our aim was to evaluate differences in gait acceleration intensity, variability, and stability of feet and trunk between older females (OF) and young females (YF) using inertial sensors. Twenty OF (mean age 68.4, SD 4.1 years) and 18 YF (mean age 22.3, SD 1.7 years) were asked to walk straight for 100 meters at their preferred speed, while wearing inertial sensors on their heels and lower back. We calculated spatiotemporal measures, foot and trunk acceleration characteristics, their variability, and trunk stability using the local divergence exponent (LDE). Two-way ANOVA (such as the factors foot and age), Student's t-test and Mann–Whitney U test were used to compare statistical differences of measures between groups. Cohen's d effects were calculated for each variable. Foot maximum vertical (VT) acceleration and amplitude, trunk-foot VT acceleration attenuation, and their variability were significantly smaller in OF than in YF. In contrast, trunk mediolateral (ML) acceleration amplitude, maximum VT acceleration, amplitude, and their variability were significantly larger in OF than in YF. Moreover, OF showed lower stability (i.e., higher LDE values) in ML acceleration, ML, and VT angular velocity of the trunk. Even though we measured healthy OF, these participants showed lower VT foot accelerations with higher VT trunk acceleration, lower trunk-foot VT acceleration attenuation, less gait stability, and more variability of the trunk, and hence, were more likely to fall. These findings suggest that instrumented gait measurements may help for early detection of changes or impairments in gait performance, even before this can be observed by clinical eye or gait speed.

Gait changes over time in hospitalized older adults with advanced dementia: Predictors of mobility change

People with dementia are at risk of mobility decline. In this study, we measured changes in quantitative gait measures over a maximum 10-week period during the course of a psychogeriatric admission in older adults with dementia, with the aims to describe mobility changes over the duration of the admission, and to determine which factors were associated with this change. Fifty-four individuals admitted to a specialized dementia inpatient unit participated in this study. A vision-based markerless motion capture system was used to record participants’ natural gait. Mixed effect models were developed with gait measures as the dependent variables and clinical and demographic variables as predictors. We found that gait stability, step time, and step length decreased, and step time variability and step length variability increased over 10 weeks. Gait stability of men decreased more than that of women, associated with an increased sacrum mediolateral range of motion over time. In addition, the sacrum mediolateral range of motion decreased in those with mild neuropsychiatric symptoms over 10 weeks, but increased in those with more severe neuropsychiatric symptoms. Our study provides evidence of worsening of gait mechanics and control over the course of a hospitalization in older adults with dementia. Quantitative gait monitoring in hospital environments may provide opportunities to intervene to prevent adverse events, decelerate mobility decline, and monitor rehabilitation outcomes.

Effects of vestibular stimulation on gait stability and variability

Vestibular information modulates muscle activity during gait, presumably to contribute stability, because noisy electrical vestibular stimulation perturbs gait stability. An important mechanism to stabilize gait in the mediolateral direction is to coordinate foot placement based on a sensory estimate of the trunk center of mass state, to which vestibular information appears to contribute. We, therefore expected that noisy vestibular stimulation would decrease the correlation between foot placement and trunk center of mass state. Moreover, as vestibular modulation of muscle activity during gait depends on step width, we expected stronger effects for narrow-base than normal walking, and smaller effects for wide-base walking. In eleven healthy subjects we measured the kinematics of the trunk (as a proxy of the center of mass), and feet, while they walked on a treadmill in six conditions, including three different step widths: control (preferred step width), narrow-base (steps smaller than hip width), and wide-base (with steps greater than hip width). The three conditions were conducted with and without a bipolar electrical stimulus, applied behind the ears (5 mA). Walking with EVS reduced gait stability but increased the foot placement to center of mass correlation in different step width conditions. The narrow-base walking was the most stable condition and showed a stronger correlation between foot placement and center of mass state. We argue that EVS destabilized gait, but that this was partially compensated for by tightened control over foot placement, which would require successful use of other than vestibular sensory inputs, to estimate center of mass movement.

Center of Pressure Trajectory and Spatiotemporal Gait Parameters When Walking with Limited Knee Flexion

Stiff-knee, which indicates reduced range of knee flexion, may decrease gait stability. Although it is closely related to an increase in fall risk, the effect of limited knee flexion on the balance capacity during walking has not been well studied. This study aimed at examining how walking with limited knee flexion would influence the center of pressure (COP) trajectory and spatiotemporal gait parameters. Sixteen healthy young participants conducted four different walking conditions: normal walking and walking with limited knee flexion of their left knee up to 40 and 20 degrees, respectively. Results show that the participants walked significantly (p<0.05) slower with shorter stride length, wider step width, less cadence, and decreased stance phase when walking with limited knee flexion, compared to normal walking. The increase in the asymmetry and variability of the COP was also observed. It indicates that limited knee flexion during walking might affect the dynamic balance.

Relationships between cognitive factors and gait strategy during exoskeleton-augmented walking

Individual variation in exoskeleton-augmented gait strategy may arise from differences in cognitive factors, e.g., ability to respond quickly to stimuli or complete tasks under divided attention. Gait strategy is defined as different approaches to achieving gait priorities (e.g., walking without falling) and is observed via changes in gait characteristics like normalized stride length or width. Changes indicate shifting priorities like increasing stability or coordination with an exoskeleton. Relationships between cognitive factors and exoskeleton gait characteristics were assessed. Cognitive factors were quantified using a modified Simon task and a speed achievement task on a self-paced treadmill with and without a secondary go/no-go task. Individuals with faster reaction times and decreased ability to maintain a given speed tended to prioritize coordination with an exoskeleton over gait stability. These correlations indicate relationships between cognitive factors and individual exoskeleton-augmented gait strategy that should be further investigated to understand variation in exoskeleton use.