Walking economy in people with Parkinson's disease

Walking with increased step length variability increases the metabolic cost of walking

Older adults and neurological populations tend to walk with slower speeds, more gait variability, and a higher metabolic cost. This higher metabolic cost could be related to their increased gait variability, but this relationship is still unclear. The purpose of this study was to determine how increased step length variability affects the metabolic cost of waking. Eighteen healthy young adults completed a set of 5-minute trials of treadmill walking at 1.20 m/s while we manipulated their step length variability. Illuminated rectangles were projected onto the surface of a treadmill to cue step length variabilities of 0, 5 and 10% (coefficient of variation). Actual step lengths and their variability were tracked with reflective markers on the feet, while metabolic cost was measured using indirect calorimetry. Changes in metabolic cost across habitual walking (no projections) and the three variability conditions were analyzed using a linear mixed effects model. Metabolic power was largest in the 10% condition (4.30 ± 0.23 W/kg) compared to 0% (4.16 ± 0.18 W/kg) and habitual (3.98 ± 0.25 W/kg). The participant's actual step length variability did not match projected conditions for 0% (3.10%) and 10% (7.03%). For every 1% increase in step length variability, there is an 0.7% increase in metabolic cost. Our results demonstrate an association between the metabolic cost of walking and gait step length variability. This suggests that increased gait variability contributes to a portion of the increased cost of walking seen in older adults and neurological populations.

Slowing of Movements in Healthy Aging as a Rational Economic Response to an Elevated Effort Landscape

Why do we move slower as we grow older? The reward circuits of the brain, which tend to invigorate movements, decline with aging, raising the possibility that reduced vigor is due to the diminishing value that our brain assigns to movements. However, as we grow older, it also becomes more effortful to make movements. Is age-related slowing principally a consequence of increased effort costs from the muscles, or reduced valuation of reward by the brain? Here, we first quantified the cost of reaching via metabolic energy expenditure in human participants (male and female), and found that older adults consumed more energy than the young at a given speed. Thus, movements are objectively more costly for older adults. Next, we observed that when reward increased, older adults, like the young, responded by initiating their movements earlier. Yet, unlike the young, they were unwilling to increase their movement speed. Was their reluctance to reach quicker for rewards due to the increased effort costs, or because they ascribed less value to the movement? Motivated by a mathematical model, we next made the young experience a component of aging by making their movements more effortful. Now the young responded to reward by reacting faster but chose not to increase their movement speed. This suggests that slower movements in older adults are partly driven by an adaptive response to an elevated effort landscape. Moving slower may be a rational economic response the brain is making to mitigate the elevated effort costs that accompany aging.

Exercise and gait/movement analyses in treatment and diagnosis of Parkinson's Disease

Cardinal motor symptoms in Parkinson's disease (PD) include bradykinesia, rest tremor and/or rigidity. This symptomatology can additionally encompass abnormal gait, balance and postural patterns at advanced stages of the disease. Besides pharmacological and surgical therapies, physical exercise represents an important strategy for the management of these advanced impairments. Traditionally, diagnosis and classification of such abnormalities have relied on partially subjective evaluations performed by neurologists during short and temporally scattered hospital appointments. Emerging sports medical methods, including wearable sensor-based movement assessment and computational-statistical analysis, are paving the way for more objective and systematic diagnoses in everyday life conditions. These approaches hold promise to facilitate customizing clinical trials to specific PD groups, as well as personalizing neuromodulation therapies and exercise prescriptions for each individual, remotely and regularly, according to disease progression or specific motor symptoms. We aim to summarize exercise benefits for PD with a specific emphasis on gait and balance deficits, and to provide an overview of recent advances in movement analysis approaches, notably from the sports science community, with value for diagnosis and prognosis. Although such techniques are becoming increasingly available, their standardization and optimization for clinical purposes is critically missing, especially in their translation to complex neurodegenerative disorders such as PD. We highlight the importance of integrating state-of-the-art gait and movement analysis approaches, in combination with other motor, electrophysiological or neural biomarkers, to improve the understanding of the diversity of PD phenotypes, their response to therapies and the dynamics of their disease progression.

Automated mechanical peripheral stimulation for gait rehabilitation in Parkinson's disease: A comprehensive review

Background

Automated Mechanical Peripheral Stimulation (AMPS) has emerged as a potential rehabilitative intervention for gait abnormalities in Parkinson's disease (PD). However, the long-term effects and combined therapy with physical exercise remain unclear. This review aimed to explore the effects of automated mechanical peripheral stimulation (AMPS) on gait and motor performance in individuals with Parkinson's disease (PD).

Methods

A research was conducted in relevant databases to identify studies investigating the effects of AMPS on gait and motor outcomes in PD patients. Inclusion criteria were set based on Population, Concept, and Context (PCC) criteria. Data extraction and analysis were performed to synthesize the findings.

Results

Ten studies met the inclusion criteria and were included in the review. The studies collectively demonstrated positive effects of AMPS on gait parameters, such as walking velocity, stride length, and walking stability. Some studies also reported improvements in functional performance and muscle activation during walking.

Conclusions

The findings suggest that AMPS holds promise as a potential intervention to improve gait and motor performance in individuals with PD. However, the evidence is limited, and further well-designed randomized controlled trials are needed to establish the long-term efficacy and optimal protocols for AMPS in PD rehabilitation.

Moving, fast and slow: behavioural insights into bradykinesia in Parkinson's disease

The debilitating symptoms of Parkinson's disease, including the hallmark slowness of movement, termed bradykinesia, were described more than 100 years ago. Despite significant advances in elucidating the genetic, molecular and neurobiological changes in Parkinson's disease, it remains conceptually unclear exactly why patients with Parkinson's disease move slowly. To address this, we summarize behavioural observations of movement slowness in Parkinson's disease and discuss these findings in a behavioural framework of optimal control. In this framework, agents optimize the time it takes to gather and harvest rewards by adapting their movement vigour according to the reward that is at stake and the effort that needs to be expended. Thus, slow movements can be favourable when the reward is deemed unappealing or the movement very costly. While reduced reward sensitivity, which makes patients less inclined to work for reward, has been reported in Parkinson's disease, this appears to be related mainly to motivational deficits (apathy) rather than bradykinesia. Increased effort sensitivity has been proposed to underlie movement slowness in Parkinson's disease. However, careful behavioural observations of bradykinesia are inconsistent with abnormal computations of effort costs due to accuracy constraints or movement energetic expenditure. These inconsistencies can be resolved when considering that a general disability to switch between stable and dynamic movement states can contribute to an abnormal composite effort cost related to movement in Parkinson's disease. This can account for paradoxical observations such as the abnormally slow relaxation of isometric contractions or difficulties in halting a movement in Parkinson's disease, both of which increase movement energy expenditure. A sound understanding of the abnormal behavioural computations mediating motor impairment in Parkinson's disease will be vital for linking them to their underlying neural dynamics in distributed brain networks and for grounding future experimental studies in well-defined behavioural frameworks.

Effort cost of reaching prompts vigor reduction in older adults

As people age, they move slower. Is age-related reduction in vigor a reflection of a reduced valuation of reward by the brain, or a consequence of increased effort costs by the muscles? Here, we quantified cost of movements objectively via the metabolic energy that young and old participants consumed during reaching and found that in order reach at a given speed, older adults expended more energy than the young. We next quantified how reward modulated movements in the same populations and found that like the young, older adults responded to increased reward by initiating their movements earlier. Yet, their movements were less sensitive to increased reward, resulting in little or no modulation of reach speed. Lastly, we quantified the effect of increased effort on how reward modulated movements in young adults. Like the effects of aging, when faced with increased effort the young adults responded to reward primarily by reacting faster, with little change in movement speed. Therefore, reaching required greater energetic expenditure in the elderly, suggesting that the slower movements and reactions exhibited in aging are partly driven by an adaptive response to an elevation in the energetic landscape of effort. That is, moving slower appears to be a rational economic consequence of aging.

Significance statement

Healthy aging coincides with a reduction in speed, or vigor, of walking, reaching, and eye movements. Here we focused on disentangling two opposing sources of aging-related movement slowing: reduced reward sensitivity due to loss of dopaminergic tone, or increased energy expenditure movements related to mitochondrial or muscular inefficiencies. Through a series of three experiments and construction of a computational model, here we demonstrate that transient changes in reaction time and movement speed together offer a quantifiable metric to differentiate between reward- and effort-based alterations in movement vigor. Further, we suggest that objective increases in the metabolic cost of moving, not reductions in reward valuation, are driving much of the movement slowing occurring alongside healthy aging.

Walking Endurance and Oxygen Uptake On-Kinetics in Individuals With Parkinson Disease Following Overground Locomotor Training

BACKGROUND AND PURPOSE

Poor walking endurance in Parkinson disease (PD) may be attributable to both bioenergetic and biomechanical factors, but locomotor training methods addressing both these factors simultaneously are understudied. Our objective was to examine the effects of overground locomotor training (OLT) on walking endurance in individuals with mild-to-moderate PD, and to further explore potential cardiorespiratory contributions.

METHODS

A single-arm, longitudinal design was used to examine the effects of 24 biweekly sessions of OLT in people with mild-to-moderate PD (n = 12). Walking endurance was measured as total distance walked during a 10-minute walk test (10minWT). Oxygen uptake (V˙ o2 ) on-kinetic profiles were determined using a monoexponential function. Perceived fatigability was assessed following the 10minWT using a self-report scale. Magnitude of change in primary outcomes was assessed using Cohen's d and adjusted for sample size (Cohen's d(unbiased) ).

RESULTS

Participants executed 3036 (297) steps and maintained 65.5% (8%) age-predicted heart rate maximum in a typical session lasting 56.9 (2.5) minutes. Medium effects in total distance walked-885.9 (157.2) versus 969.5 (140.9); Cohen's d(unbiased) = 0.54-and phase II time constant of the V˙ o2 on-kinetic profile-33.7 (12.3) versus 25.9 (15.3); Cohen's d(unbiased) = 0.54-were observed alongside trivial effects for perceived fatigability-4.7 (1.4) versus 4.8 (1.5); Cohen's d(unbiased) = 0.11-following OLT.

DISCUSSION AND CONCLUSIONS

These preliminary findings may demonstrate the potential for moderate-intensity OLT to improve walking endurance and enhance cardiorespiratory adjustments to walking activity in adults with mild-to-moderate PD.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A407 ).

The effect of exercise on walking economy in patients with chronic neurological conditions: A systematic review and meta-analysis

Introduction

To investigate the effect of exercise on the walking economy (WE) of patients with chronic neurological conditions (CNCs) and to determine the type of physical activity that best improves the WE of patients with CNCs.

Methods

Four electronic databases were searched until December 2022 (Web of Science, PubMed, Cochrane, and CINAHL). Studies were screened using the following inclusion criteria: 1. randomized controlled or non-randomized controlled trials; 2. exercise interventions >4 weeks in duration; 3. patients aged ≥18 years with a diagnosis of CNCs. 4. walking economy of patients measured before and after the intervention. The PEDro scale was used to assess the methodological quality of the included studies.

Results and discussion

Twenty-two studies met the inclusion criteria. Meta-analysis results showed that exercise significantly improved WE (g = -0.352, 95% CI, -0.625 to -0.078, P = 0.012). Subgroup analysis revealed that patients who received exercise showed better WE compared with those who underwent no control intervention (g = -0.474, 95% CI, -0.636 to -0.311, P < 0.001). However, exercise therapy did not show a significant improvement of WE compared with control groups (g = -0.192, 95% CI, -0.451 to 0.067, P = 0.146). In addition, we found that endurance combined with resistance, high-intensity intermittent, and other training modalities resulted in better WE compared with the pre-intervention. Of these, interval training has the greatest effect on improving WE. In conclusion, exercise can improve WE in patients with CNCs. More randomized controlled trials are necessary for the future.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022361455, identifier: CRD42022361455.

Effects of automatic mechanical peripheral stimulation on gait biomechanics in older adults with Parkinson's disease: a randomized crossover clinical trial

BACKGROUND

Automated mechanical peripheral stimulation (AMPS) is a rehabilitation technique suggested to correct gait abnormalities on Parkinson's disease. Although previous studies have suggested increments in functional performance and gait speed after AMPS intervention, little is known about its effect on gait biomechanics.

OBJECTIVE

To analyze the effect of an AMPS session on functional performance and gait biomechanics in subjects with Parkinson's disease.

METHODS

Twenty-eight subjects aged 67±3 years old participated in this study. Kinematics and muscle activation were recorded during walking at a preferred gait speed before and after AMPS and sham interventions. Footswitches sensors were used to record the kinematic parameters. Electromyographic (EMG) signals of tibialis anterior (TA) and gastrocnemius lateralis (GL) were recorded. Timed up and go (TUG) test and Short Physical Performance Battery (SPPB) were performed to assess functional performance.

RESULTS

GL activation increased after AMPS intervention before and after heel strike (p = 0.04; p < 0.01) and before and after toe-off (p = 0.013; p = 0.038). Also, after AMPS intervention, TA activation increased after heel strike (p = 0.007); and after sham intervention, TA activation reduced before and after heel strike (p = 0.038; and p = 0.007) and before toe-off (p = 0.013). The time of TUG test was shorter after AMPS intervention (p = 0.015).

CONCLUSION

AMPS intervention changed the EMG activation of ankle muscles during walking and functional performance. However, AMPS intervention did not change gait kinematics.

Oxygen Cost of Walking in People With Multiple Sclerosis and Its Association With Fatigue: A Systematic Review and Meta-analysis

BACKGROUND

This systematic review and meta-analysis aimed to compare the oxygen cost of walking in individuals with multiple sclerosis (MS) and controls and to assess the relationship between oxygen cost of walking and fatigue in individuals with MS.

METHODS

Four databases (CINAHL, MEDLINE, ProQuest, Web of Science) were searched up to September 2020. Studies were included if they recruited adults with MS and either compared oxygen cost of walking in those with MS and a control population or determined the relationship between oxygen cost of walking and fatigue. Meta-analysis of the standardized mean difference in oxygen cost of walking between individuals with MS and controls was performed.

RESULTS

Nine studies were included in this review, of which 7 compared oxygen cost of walking in individuals with MS (n = 176) and controls (n = 142) and 4 investigated the relationship between oxygen cost of walking and fatigue. Meta-analysis revealed that individuals with MS (with predominantly mild-to-moderate disability) had a significantly higher oxygen cost of walking compared with controls (standardized mean difference = 2.21, 95% CI = 0.88 to 3.54, P = .001). In addition, 3 studies found a significant yet weak positive association between oxygen cost of walking and fatigue.

CONCLUSIONS

Individuals with MS expend more energy when walking compared with controls. This increase in energy expenditure may contribute to the development of fatigue, as some studies found that higher oxygen costs of walking were associated with greater fatigue. Future studies should investigate whether reducing energy expenditure during movement improves fatigue.

Biomechanical responses of Nordic walking in people with Parkinson's disease

In healthy adults, Nordic walking (NW) is known to increase the external mechanical energy fluctuations, though the external work is unaltered due to an improved pendulum-like recovery in comparison with free walking (FW). We aimed to compare mechanical, pendulum-like, and spatiotemporal parameters of gait at different speeds with and without NW poles in people with Parkinson's disease and healthy controls. The study included 11 people (aged 65.6 ± 7.0 years) with idiopathic Parkinson's disease, scoring between 1 and 1.5 on the Hoehn and Yahr scale (H&Y), and nine healthy controls (aged 70.0 ± 5.6 years). All the people were experienced Nordic walkers. Walking tests were performed at 1.8 km h^-1 and 4.7 km h^-1 , on eight 3D force platforms on a walkway. We found greater pendulum-like energy recovery (p < 0.05) in the Parkinson group during NW than in FW, while external mechanical work remained similar (p > 0.05). People with Parkinson's disease showed a major increase in vertical and forward energy fluctuations using poles than in healthy controls. In addition, the Parkinson group showed increased stride frequency and reduced stride length compared to controls in the NW and FW conditions. Our findings partly justify the lower walking economy in Parkinson's disease due to reduced pendulum-like mechanism at commonly used speeds. NW alters gait mechanics similarly in Parkinson group and healthy control, increasing the total mechanical work. Therefore, NW can be a compelling strategy for rehabilitation because of its potential for improving functional mobility, increasing pendulum-like mechanism in Parkinson's disease.

The Cost of Gait Slowness: Can Persons with Parkinson's Disease Save Energy by Walking Faster?

BACKGROUND

Gait slowing is a common feature of Parkinson's disease (PD). Many therapies aim to improve gait speed in persons with PD, but goals are often imprecise. How fast should each patient walk? And how do persons with PD benefit from walking faster? There is an important need to understand how walking speed affects fundamental aspects of gait-including energy cost and stability-that could guide individualized therapy decisions in persons with PD.

OBJECTIVE

We investigated how changes in walking speed affected energy cost and spatiotemporal gait parameters in persons with PD. We compared these effects between dopaminergic medication states and to those observed in age-matched control participants.

METHODS

Twelve persons with PD and twelve control participants performed treadmill walking trials spanning at least five different speeds (seven speeds were desired, but not all participants could walk at the fastest speeds). Persons with PD participated in two walking sessions on separate days (once while optimally medicated, once after 12-hour withdrawal from dopaminergic medication). We measured kinematic and metabolic data across all trials.

RESULTS

Persons with PD significantly reduced energy cost by walking faster than their preferred speeds. This held true across medication conditions and was not observed in control participants. The patient-specific walking speeds that reduced energy cost did not significantly affect gait variability metrics (used as proxies for gait stability).

CONCLUSION

The gait slowing that occurs with PD results in energetically suboptimal walking. Rehabilitation strategies that target patient-specific increases in walking speed could result in a less effortful gait.

The Thermodynamic Consequences of Parkinson's Disease

Several lines of evidence point to a pervasive disturbance of energy balance in Parkinson's disease (PD). Weight loss, common and multifactorial, is the most observable sign of this. Bradykinesia may be best understood as an underinvestment of energy in voluntary movement. This accords with rodent experiments that emphasise the importance of dopamine in allocating motor energy expenditure. Oxygen consumption studies in PD suggest that, when activities are standardised for work performed, these inappropriate energy thrift settings are actually wasteful. That the dopaminergic deficit of PD creates a problem with energy efficiency highlights the role played by the basal ganglia, and by dopamine, in thermodynamic governance. This involves more than balancing energy, since living things maintain their internal order by controlling transformations of energy, resisting probabilistic trends to more random states. This review will also look at recent research in PD on the analysis of entropy-an information theory metric of predictability in a message-in recordings from the basal ganglia. Close relationships between energy and information converge around the concept of entropy. This is especially relevant to the motor system, which regulates energy exchange with the outside world through its flow of information. The malignant syndrome in PD, a counterpart of neuroleptic malignant syndrome, demonstrates how much thermodynamic disruption can result from breakdown of motor signalling in an extreme hypodopaminergic state. The macroenergetic disturbances of PD are consistent with a unifying hypothesis of dopamine's neurotransmitter actions-to adapt energy expenditure to prevailing economic circumstances.

Association of walking energetics with amyloid beta status: Findings from the Baltimore Longitudinal Study of Aging

INTRODUCTION

Higher energetic costs for mobility predict gait speed decline. Slow gait is linked to cognitive decline and Alzheimer's disease (AD). Whether the energetic cost of walking is linked to AD pathology is unknown. We investigated the cross-sectional association between the energetic cost of walking, gait speed, and amyloid beta (Aβ) status (+/-) in older adults.

METHODS

One hundred forty-nine cognitively normal adults (56% women, mean age 77.5 ± 8.4 years) completed customary-paced walking assessments with indirect calorimetry and 11C-Pittsburgh compound B positron emission tomography. Logistic regression models examined associations adjusted for demographics, body composition, comorbid conditions, and apolipoprotein E ε4.

RESULTS

Each 0.01 mL/kg/m greater energy cost was associated with 18% higher odds of being Aβ+ (odds ratio [OR] = 1.18; 95% confidence interval [CI]: 1.04 to 1.34; P = .011). These findings were not observed when investigating gait speed (OR = 0.99; 95% CI: 0.97 to 1.01; P = .321).

DISCUSSION

High energetic cost of walking is linked to AD pathology and may be a potential target for therapeutic intervention.

Non-motor impairments affect walking kinematics in Parkinson disease patients: A cross-sectional study

BACKGROUND

In patients with Parkinson disease (PD), severe postural and gait impairments are rarely observed in early stage of disease and non-motor symptoms (NMS) are often overlooked.

OBJECTIVE

This observational study aimed to characterize the impact of non-motor impairments on walking kinematics in early stages PD patients, and to assess the differences of gait parameters and NMS between PD patients with and without mild cognitive impairment (MCI).

METHODS

Twenty-six patients with Modified Hoehn and Yahr Scale score≤2 were evaluated for NMS using Kings Parkinson's Pain Scale, Parkinson Fatigue Severity scale, Parkinson Anxiety Scale, Beck Depression Inventory and Epworth Sleepiness Scale, kinematic parameters through an inertial sensor and cognitive performance by a comprehensive neuropsychological battery.

RESULTS

Fatigue had a moderate negative correlation with step cadence, and a moderate to strong positive correlation with gait duration, Timed Up and Go (TUG) and TUG Dual Task (p < 0.01). Pain showed positive moderate correlation with gait duration (p < 0.01). Twelve patients resulted affected by MCI and reported significantly worse scores in gait duration, pain and fatigue (p < 0.05). According to cognitive z scores, PD-MCI group showed a moderate negative correlation between visuospatial abilities and fatigue (p < 0.05).

CONCLUSIONS

NMS significantly affect walking kinematics whereas a limited role of cognitive status on motor performance occur in the early PD stages.

Accelerometer output and its association with energy expenditure in persons with mild-to-moderate Parkinson's disease

OBJECTIVE

This study examined the association between ActiGraph accelerometer output and energy expenditure across different speeds of walking in persons with Parkinson's disease (PD), and further generated cut-points that represent a metric for quantifying time spent in moderate-to-vigorous physical activity (MVPA) among persons with PD.

METHODS

The sample included 30 persons with mild-to-moderate PD (Hoehn and Yahr stages 2-3) and 30 adults without PD matched by sex and age. All participants completed 5 minutes of quiet, seated rest and then underwent three, 6-minute bouts of walking on a treadmill at three different speeds relative to the individual's self-selected pace. Activity counts were measured using an ActiGraph accelerometer worn at the waist level on the least affected side for persons with PD and the dominant side for controls. The rate of oxygen consumption, or energy expenditure, was measured using a portable, open-circuit spirometry system.

RESULTS

Our results indicated a strong association between activity counts and energy expenditure for persons with PD (R2 = 0.87) and controls (R2 = 0.89). However, the significant difference in slopes resulted in a lower cut-point of 1,354 counts·min-1 for persons with PD than the cut-point of 2,010 counts·min-1 for controls.

CONCLUSION

Our results support the application of the disease-specific cut-point for quantifying the amount of time spent in MVPA using ActiGraph accelerometers among persons with mild-to-moderate PD. Such an application may provide accurate estimates of MVPA in this population, and better inform future research examining the possible determinants and consequences of physical activity as well as testing of interventions for changing MVPA in PD.

Fatigability and Cardiorespiratory Impairments in Parkinson's Disease: Potential Non-Motor Barriers to Activity Performance

Parkinson's disease (PD) is the second most common neurodegenerative condition after Alzheimer's disease, affecting an estimated 160 per 100,000 people 65 years of age or older. Fatigue is a debilitating non-motor symptom frequently reported in PD, often manifesting prior to disease diagnosis, persisting over time, and negatively affecting quality of life. Fatigability, on the other hand, is distinct from fatigue and describes the magnitude or rate of change over time in the performance of activity (i.e., performance fatigability) and sensations regulating the integrity of the performer (i.e., perceived fatigability). While fatigability has been relatively understudied in PD as compared to fatigue, it has been hypothesized that the presence of elevated levels of fatigability in PD results from the interactions of homeostatic, psychological, and central factors. Evidence from exercise studies supports the premise that greater disturbances in metabolic homeostasis may underly elevated levels of fatigability in people with PD when engaging in physical activity. Cardiorespiratory impairments constraining oxygen delivery and utilization may contribute to the metabolic alterations and excessive fatigability experienced in individuals with PD. Cardiorespiratory fitness is often reduced in people with PD, likely due to the combined effects of biological aging and impairments specific to the disease. Decreases in oxygen delivery (e.g., reduced cardiac output and impaired blood pressure responses) and oxygen utilization (e.g., reduced skeletal muscle oxidative capacity) compromise skeletal muscle respiration, forcing increased reliance on anaerobic metabolism. Thus, the assessment of fatigability in people with PD may provide valuable information regarding the functional status of people with PD not obtained with measures of fatigue. Moreover, interventions that target cardiorespiratory fitness may improve fatigability, movement performance, and health outcomes in this patient population.

Oxygen cost of over-ground walking in persons with mild-to-moderate Parkinson's disease

BACKGROUND

Oxygen (O₂) cost of walking is a physiological marker of walking dysfunction and reflects the amount of O₂ consumed per kilogram of body weight per unit distance walked. The onset of walking dysfunction (i.e., reduced walking speed and shorter stride length) is commonly observed in Parkinson's disease (PD), even in the early stages of the disease. However, the O₂ cost of walking has not been assessed in persons with PD.

RESEARCH QUESTION

Does O₂ cost of walking differ between persons with PD and controls matched by age and sex?

METHODS

The sample included 31 persons with mild-to-moderate PD (Hoehn and Yahr stages 2-3) and 31 age- and sex-matched controls in this cross-sectional study. O₂ consumption (VO₂) was measured using a portable indirect calorimetry system during a 6-min period of over-ground walking at a normal comfortable speed, and the O₂ cost of walking was calculated based on the ratio of net relative VO₂ (ml kg^-1 min^-1) and speed (m min^-1).

RESULTS

There were no differences in resting VO₂, steady-state VO₂, and over-ground walking speed between persons with PD and controls (p > 0.05). There was a significant difference in the O₂ cost of walking between persons with PD and healthy controls (p < 0.01) such that persons with PD had a higher O₂ cost of walking. The mean(SD) O₂ cost of walking for persons with PD was 0.179 (0.038) ml kg^-1 m^-1, and the O₂ cost of walking for healthy controls was 0.153 (0.024) ml kg^-1 m^-1.

SIGNIFICANCE

Persons with PD demonstrated a higher O₂ cost of walking compared with controls, and this may reflect worse walking economy in PD. The possibility of worse walking economy under free-living conditions may result in reduced community ambulation and participation.

Maximal strength training in patients with Parkinson's disease: impact on efferent neural drive, force-generating capacity, and functional performance

Parkinson's disease (PD) is characterized by progressive neurological deterioration, typically accompanied by reductions in skeletal muscle force-generating capacity (FGC) and functional performance. Physical activity has the potential to counteract this debilitating outcome, however, it is elusive if high-intensity strength training included in conventional treatment may improve results. Therefore, we randomly assigned 22 PD patients (74 ± 9 yr) to conventional rehabilitation with or without maximal strength training (MST) performed as leg press and chest press at ~90% of one repetition maximum (1RM), five times per week for 4 wk. FGC, physical performance, and efferent neural drive assessed as evoked potentials (V-wave normalized to M-wave in m. soleus) were measured following training. Results revealed that only MST improved 1RM leg press (101 ± 23 to 118 ± 18 kg) and chest press (36 ± 15 to 41 ± 15 kg), plantar flexion maximal voluntary contraction (235 ± 125 to 293 ± 158 N·m), and rate of force development (373 ± 345 to 495 ± 446 N·m·s^-1; all P < 0.05; different from controls P < 0.05). FGC improvements were accompanied by an increased efferent neural drive to maximally contracting musculature (V-to-M ratio: 0.17 ± 0.12 to 0.24 ± 0.15; P < 0.05; different from controls P < 0.05), improved physical performance (stair climbing: 21.0 ± 9.2 to 14.4 ± 5.2 s; timed up and go: 7.8 ± 3.3 to 6.2 ± 2.5 s; both P < 0.05), and self-perceived improvement in health (3.1 ± 0.5 to 2.6 ± 0.9) and social activities functioning (2.2 ± 1.0 to 1.5 ± 1.1; both P < 0.05). No changes were observed in the control group. In conclusion, this study shows that MST improves FGC, neuromuscular function, and functional performance and advocates that high-intensity strength training should be implemented as an adjunct therapy in the treatment of PD patients.NEW & NOTEWORTHY This randomized, controlled trial documents that supervised high-intensity strength training improves efferent neural drive, maximal muscle strength, rate of force development, and functional performance in patients with Parkinson's disease (PD). In contrast, no differences were observed in these outcome variables in patients receiving conventional treatment consisting of recreational physical activity with low-to-medium intensity. Consequently, this study advocates that high-intensity strength training should be implemented in the clinical treatment of PD patients.

Cardiopulmonary Function and Aerobic Exercise in Parkinson's: A Systematic Review of the Literature

Background

Cardiorespiratory impairments are considered the main cause of mortality in the late stages of Parkinson's. Aerobic exercise has been shown to improve pulmonary function in asthmatic patients and in healthy people. However, effects of aerobic exercise on cardiopulmonary function in people with Parkinson's have not been investigated. Therefore, this study aimed to review the effects of aerobic exercise on cardiopulmonary function in people with Parkinson's.

Methods

A systematic search was conducted using MEDLINE, AMED, CINHAL Plus, and relevant associated keywords, from January 1970 to January 2020. Inclusion criteria for the studies were: aerobic exercise as part of the intervention, pulmonary function test, and/or cardiopulmonary exercise test as outcome measures.

Results

In total, 329 citations were identified from the search, of which nine were included in this review. In general, aerobic exercise was found to have positive effects on cardiac function for people with Parkinson's, but there is a lack of studies on the effects of aerobic exercise on pulmonary function.

Conclusion

People with early stages of Parkinson's may experience positive effects of aerobic exercise on cardiac fitness. Further research is needed in this area, particularly into the effects of aerobic exercise on pulmonary function in early stages of the disease.

Can fatigue predict walking capacity of patients with Parkinson's disease?

Although fatigue is an expressive symptom of Parkinson's disease (PD), few studies have investigated the association between fatigue, mobility and walking capacity of these patients.

OBJECTIVE

To investigate whether fatigue is an independent factor associated with mobility and the walking capacity in patients with PD.

METHODS

Forty-eight patients with PD (22 with fatigue) were tested for mobility and their walking capacity: Timed Up and Go (TUG), 10-Meter Walk Test (10MWT) at usual and fastest speed, and 6-Minute Walk Test (6MWT). Fatigue was measured with Parkinson's Fatigue Scale (PFS-16). Linear regression analysis was used to investigate if fatigue is an independent factor contributing to variance in mobility and walking capacity.

RESULTS

There was a positive correlation between PFS-16 and TUG (rs=0.385; p=0.007). There was a negative correlation between PFS-16 and 10MWT at comfortable (r=-0.385; p=0.007) and fast speeds (r=-0.396; p=0.005), and 6MWT (r=-0.472; p=0.001). Linear regression analysis revealed that fatigue did not explain the variance of TUG and 10MWT. PFS-16, age and section III of UPDRS explained 49.6% (adjusted R2; p<0.001) variance in the 6MWT, and fatigue was the most significant predictor (F=-32.1; p=0.022).

CONCLUSIONS

Fatigue is an independent factor contributing to the distance covered during 6MWT in patients with PD. Our results highlight the importance of recognition and management of this symptom.

The timing of locomotor propulsion in healthy adults walking at multiple speeds

In computational models of human walking, both magnitude and timing of locomotor propulsion are important for mechanical and metabolic efficiency, suggesting that these are likely tightly controlled by the neuromuscular system. Studies of actual human walking have focused primarily on magnitude-related measures of propulsion, often ignoring its timing. The purpose of this study was to quantify the timing of onset and peak propulsion relative to contralateral heel strike (HS) in healthy, young adults walking at multiple speeds. Propulsion was quantified at the ground-level using the anterior component of the anteroposterior ground reaction force, the limb-level using individual limb power, and the joint-level using ankle power. Contrary to common computational models, most of our timing-related measures indicated that propulsion occurred after contralateral HS. Timing-related measures of propulsion also changed with walking speed - as speed increased, individuals initiated propulsion earlier in the support phase. Timing of locomotor propulsion is theoretically important for walking performance, especially metabolic efficiency, and could therefore provide important clinical information. This study provides a set of relatively simple metrics that can be used to quantify propulsion and benchmark data that can be used for future comparisons with individuals or populations with gait impairments.

Exercise for Parkinson's disease

Parkinson's disease is the second most common neurodegenerative disease with a prevalence rate of 1-2 per 1000 of the population worldwide. Pharmacological management is the mainstay of treatment. Despite optimal medication, motor impairment particularly balance and gait impairment persist leading to various degree of disability and reduced quality-of-life. The present review describes motor impairment including postural impairment, gait dysfunction, reduced muscle strength and aerobic capacity and falls. Physical therapy and complementary exercises have been proven to improve motor performance and functional mobility. Evidence on the efficacy of physical therapy and complementary exercises is presented in this review. These exercises include gait training with cues, gait training with treadmill, Nordic walking, brisk walking, balance training, virtual reality interventions, Tai Chi and dance. All these treatment interventions produce short-term beneficial effects and some interventions demonstrate long-term benefit. Gait training with treadmill enhance walking performance and the effects sustain for 3-6 months. Balance training improves balance, function and reduces fall rate, and these effects carry over to at least 12 months after training ended. Sustained Tai Chi for 6 months, dance therapy for 12 months, progressive resistive training for 24 months alleviates the PD motor symptoms, suggesting that they could slow down PD progression. Based on this evidence, individuals with PD are encouraged to sustain their training in order to improve/maintain their physical ability and to combat the progression of PD.

Trading Symmetry for Energy Cost During Walking in Healthy Adults and Persons Poststroke

Background. Humans typically walk in ways that minimize energy cost. Recent work has found that healthy adults will even adopt new ways of walking when a new pattern costs less energy. This suggests potential for rehabilitation to drive changes in walking by altering the energy costs of walking patterns so that the desired pattern becomes energetically optimal (ie, costs least energy of all available patterns). Objective. We aimed to change gait symmetry in healthy adults and persons poststroke by creating environments where changing symmetry allowed the participants to save energy. Methods. Across 3 experiments, we tested healthy adults (n = 12 in experiment 1, n = 20 in experiment 2) and persons poststroke (n = 7 in experiment 3) in a novel treadmill environment that linked asymmetric stepping and gait speed-2 factors that influence energy cost-to create situations where walking with one's preferred gait symmetry (or asymmetry, in the case of the persons poststroke) was no longer the least energetically costly way to walk. Results. Across the 3 experiments, we found that most participants changed their gait when experiencing the new energy landscape. Healthy adults often adopted an asymmetric gait if it saved energy, and persons poststroke often began to step more symmetrically than they prefer to walk in daily life. Conclusions. We used a novel treadmill environment to show that people with and without stroke change clinically relevant features of walking to save energy. These findings suggest that rehabilitation approaches aimed at making symmetric walking energetically "easier" may promote gait symmetry after stroke.

Intersegmental coordination patterns are differently affected in Parkinson's disease and cerebellar ataxia

The law of intersegmental coordination (Borghese et al. 1996) may be altered in pathological conditions. Here we investigated the contribution of the basal ganglia (BG) and the cerebellum to lower limb intersegmental coordination by inspecting the plane's orientation and other parameters pertinent to this law in patients with idiopathic Parkinson's disease (PD) or cerebellar ataxia (CA). We also applied a mathematical model that successfully accounts for the intersegmental law of coordination observed in control subjects (Barliya et al. 2009). In the present study, we compared the planarity index (PI), covariation plane (CVP) orientation, and CVP orientation predicted by the model in 11 PD patients, 8 CA patients, and two groups of healthy subjects matched for age, height, weight, and gender to each patient group (Ctrl_PD and Ctrl_CA). Controls were instructed to alter their gait speed to match those of their respective patient group. PD patients were examined after overnight withdrawal of anti-parkinsonian medications (PD-off-med) and then on medication (PD-on-med). PI was above 96% in all gait conditions in all groups suggesting that the law of intersegmental coordination is preserved in both BG and cerebellar pathology. However, the measured and predicted CVP orientations rotated in PD-on-med and PD-off-med compared with Ctrl_PD and in CA vs. Ctrl_CA. These rotations caused by PD and CA were in opposite directions suggesting differences in the roles of the BG and cerebellum in intersegmental coordination during human locomotion. NEW & NOTEWORTHY Kinematic and muscular synergies may have a role in overcoming motor redundancies, which may be reflected in intersegmental covariation. Basal ganglia and cerebellar networks were suggested to be involved in crafting and modulating synergies. We thus compared intersegmental coordination in Parkinson's disease and cerebellar disease patients and found opposite effects in some aspects. Further research integrating muscle activities as well as biomechanical and neural control modeling are needed to account for these findings.

Acute Cardiometabolic Responses to Three Modes of Treadmill Exercise in Older Adults With Parkinson's Disease

The purpose of this study was to compare acute cardiometabolic responses to 3 modes of treadmill exercise in adults diagnosed with Parkinson's disease (PD). Eight elderly adults with PD (67.9 ± 3.0 yr) completed 1 session each on a land, aquatic, and antigravity treadmill at 50% body weight. Participants walked from 1 to 3 mph in 0.5-mph increments at 0% grade for 5 min at each speed. Heart rate, energy expenditure, blood pressure, and rating of perceived exertion were measured at rest and during exercise. All variables except diastolic blood pressure increased with speed on all treadmills (p < .001). At all speeds except 1.5 mph, heart rate was higher on the land treadmill than the antigravity treadmill (p < .05). Exercising on an aquatic or antigravity treadmill elicits similar submaximal physiologic responses to exercise on a land treadmill in adults with PD.

Accuracy of wearable physical activity trackers in people with Parkinson's disease

INTRODUCTION

The purpose of this study was to determine the accuracy of the Fitbit Charge HR™ and Garmin vívosmart^® HR in measuring steps and reflecting intensity of activity in people with Parkinson's disease (PD).

METHODS

Thirty-three people with mild-moderate PD performed six, two-minute indoor walks at their self-selected walking pace, and at target cadences of 60, 80, 100, 120 and 140 beats/min. A 500 m outdoor walk with terrain challenges was also performed. Step count was recorded by the two wrist-worn activity trackers (Fitbit Charge HR™ and Garmin vívosmart^® HR) and compared to an accelerometer (ActivPAL³™). Intensity was recorded by a portable breath-by-breath gas analyser (VO₂), heart rate and Borg scale.

RESULTS

Both commercial activity trackers had low error (<3%) and moderate to high consistency at self-selected pace both indoors and outdoors (ICC 0.88-0.97; p < 0.05) compared to the ActivPAL³™. The Garmin recorded low error (<5%) and high agreement (ICCs > 0.68; p < 0.001) for all target cadences ≥80steps/min. The Fitbit had higher error was less consistent for all target cadences ≥80steps/min. Cadence measured by the Fitbit and Garmin weakly reflected increases in heart rate (ICCs 0.27-0.28; p < 0.05), and did not reflect VO₂ or Borg (ICCs 0.08-0.15, p > 0.05).

CONCLUSION

The Garmin device was more accurate at reflecting step count across a broader range of walking cadences than the Fitbit, but neither strongly reflected intensity of activity. While not intended to replace research grade devices, these wrist-worn devices may be a clinically useful adjunct to exercise therapy to increase physical activity in people with PD.

Factors Contributing to Perceived Walking Difficulties in People with Parkinson's Disease

BACKGROUND

While walking difficulties are common in people with Parkinson's disease (PD), little is known about factors that independently contribute to their perceived walking difficulties.

OBJECTIVE

To identify factors that independently contribute to perceived walking difficulties in people with PD.

METHODS

This study involved 243 (62% men) participants; their mean (min-max) age and PD duration were 70 (45-93) and 8 (1-43) years, respectively. A postal survey preceded a home visit that included observations, clinical tests, questions and questionnaires that were administered as a structured interview. Perceived walking difficulties (dependent variable) were assessed with the self-administered generic Walk-12 (Walk-12G, scored 0-42, higher = worse). Independent variables included personal (e.g., age and general self-efficacy) and social environmental factors (e.g., social support and living situation) as well as disease-related factors including motor (e.g., freezing of gait (FOG) and postural instability) and non-motor symptoms (e.g., fatigue and orthostatic hypotension). Linear multiple regression analysis was used to identify factors that independently contributed to perceived walking difficulties.

RESULTS

Eight significant independent variables explained 56.3% of the variance in perceived walking difficulties. FOG was the strongest significant contributing factor to perceived walking difficulties, followed by general self-efficacy, fatigue, PD duration, lower extremity function, orthostatic hypotension, bradykinesia and postural instability.

CONCLUSION

Motor and non-motor symptoms as well as personal factors (i.e., general self-efficacy) seem to be of importance for perceived walking difficulties in PD. These findings might nurture future interventions that address modifiable factors in order to enhance walking ability in people with PD.

Metabolic and kinematic parameters during walking with poles in Parkinson's disease

In healthy people, energy expenditure is generally higher during walking with poles (WP) than during conventional walking (W). In persons with Parkinson's disease (PD), walking is slower and may be associated with greater energy consumption, stride-to-stride variability, and difficulty in regulating stride length. The aim of this study was to determine whether treadmill WP at three different speeds could induce changes in gait kinematics and oxygen consumption in PD patients. The study sample was 20 patients with mild-to-moderate PD and 20 age-matched healthy controls. Subjects underwent 5-min W and WP treadmill tests at three different speeds (2.5, 3.5, and 4.5 km/h). Metabolic and gait parameters (ventilation, gas exchange, stride count and length) were recorded. As compared with the healthy controls, higher energy consumption (P < 0.05) (and other metabolic parameters), shorter stride, and reduced cadence (P < 0.05) were observed for the PD patients, independent of the walking technique. All subjects were noted to take longer strides during WP (P < 0.001), especially at the lowest treadmill speed. However, significantly higher energy consumption was observed only for the healthy controls (P < 0.05). No changes in metabolic parameters during WP were recorded; however, a substantial improvement in gait cycle length was noted for the PD patients.

Clinical utility of the 6-min walk test for patients with moderate Parkinson's disease

The aim of this study was to test the clinical utility of the 6-min walk test (6MWT) for patients with moderate Parkinson's disease (PD) through a determination of factors related to this test. This was a descriptive, observational study carried out at a General Hospital, in-patients. Twenty-four patients with moderate PD were studied. We used Hoehn and Yahr stage ratings (HY stage), Unified Parkinson Disease Rating Scales (UPDRS) motor examination score, 6MWT, Berg Balance scale, Timed 'Up & Go' test (TUG), 10-m walk test (10-m walk speed, 10-m walk steps and cadence), and the energy cost of walking (Ec). The average HY stage was 3.1±0.5 and 6MWT was 340.8±110.9 m. TUG (r=-0.68, P<0.01) and Ec (r=-0.65, P<0.01) were correlated significantly with 6MWT. Multiple regression analysis with age, HY stage, TUG, cadence, and Ec as variables indicated a significant degree of variability in the 6MWT results (R=0.77, P<0.001). The TUG (β=-0.47, P<0.01) and Ec (β=-0.4, P<0.01) were correlated independently with the 6MWT results. In contrast, age, HY stage, and cadence were not independently correlated. The 6MWT is a simple tool for assessing walking capacity for patients with PD. In this study, we confirmed the convergent validity and clinical utility of the 6MWT for patients with moderate PD. The 6MWT is useful for clinical assessment to guide the planning of rehabilitation treatment for patients with moderate PD.

Outcome on Balance and Gait Following Botulinum Toxin Treatment for Striatal Foot in Parkinson's Disease

BACKGROUND

Striatal foot deformity can shorten the stance phase of gait and impair the ability to stand and walk. Botulinum neurotoxin type A (BoNT A) is a treatment option. However, no previous study has included clinical balance testing in the evaluation of treatment effects. The aim of this study was to evaluate gait and balance in patients with striatal foot deformities and Parkinson's disease (PD) before and after treatment with BoNT A injections.

METHOD

The study included 10 patients with PD and striatal foot deformity who visited a neurological clinic. The mean ± standard deviation age and PD-duration was 62.8 ± 8.8 years and 4.9 ± 3.6 years, respectively. Clinical assessment was made before and 4 and 16 weeks after injection and included 5 clinical gait and balance tests. The intensity of distress due to deformities was investigated with a visual analogue scale. Parkinsonian motor status was assessed with the Unified Parkinson's Disease Rating Scale part III (motor part). Based on ordinary clinical examination, electromyography-guided BoNT A injection was given in affected muscles. Clinically effective doses of BoNT A were used.

RESULTS

Improvements were observed regarding functional, dynamic, and standing balance as well as intensity of distress at 4 weeks but not at 16 weeks compared with baseline.

CONCLUSIONS

BoNT A injection treatment improved gait and balance in patients with PD and striatal foot deformities. Multicenter trials are needed; and, to achieve increased power, a randomized, double-blind controlled design is needed and should focus on the ability of tests to capture subtle changes in gait and balance.

Prolonged Walking with a Wearable System Providing Intelligent Auditory Input in People with Parkinson's Disease

Rhythmic auditory cueing is a well-accepted tool for gait rehabilitation in Parkinson's disease (PD), which can now be applied in a performance-adapted fashion due to technological advance. This study investigated the immediate differences on gait during a prolonged, 30 min, walk with performance-adapted (intelligent) auditory cueing and verbal feedback provided by a wearable sensor-based system as alternatives for traditional cueing. Additionally, potential effects on self-perceived fatigue were assessed. Twenty-eight people with PD and 13 age-matched healthy elderly (HE) performed four 30 min walks with a wearable cue and feedback system. In randomized order, participants received: (1) continuous auditory cueing; (2) intelligent cueing (10 metronome beats triggered by a deviating walking rhythm); (3) intelligent feedback (verbal instructions triggered by a deviating walking rhythm); and (4) no external input. Fatigue was self-scored at rest and after walking during each session. The results showed that while HE were able to maintain cadence for 30 min during all conditions, cadence in PD significantly declined without input. With continuous cueing and intelligent feedback people with PD were able to maintain cadence (p = 0.04), although they were more physically fatigued than HE. Furthermore, cadence deviated significantly more in people with PD than in HE without input and particularly with intelligent feedback (both: p = 0.04). In PD, continuous and intelligent cueing induced significantly less deviations of cadence (p = 0.006). Altogether, this suggests that intelligent cueing is a suitable alternative for the continuous mode during prolonged walking in PD, as it induced similar effects on gait without generating levels of fatigue beyond that of HE.

Are the average gait speeds during the 10meter and 6minute walk tests redundant in Parkinson disease?

We investigated the relationships between average gait speed collected with the 10Meter Walk Test (Comfortable and Fast) and 6Minute Walk Test (6MWT) in 346 people with Parkinson disease (PD) and how the relationships change with increasing disease severity. Pearson correlation and linear regression analyses determined relationships between 10Meter Walk Test and 6MWT gait speed values for the entire sample and for sub-samples stratified by Hoehn & Yahr (H&Y) stage I (n=53), II (n=141), III (n=135) and IV (n=17). We hypothesized that redundant tests would be highly and significantly correlated (i.e. r>0.70, p<0.05) and would have a linear regression model slope of 1 and intercept of 0. For the entire sample, 6MWT gait speed was significantly (p<0.001) related to the Comfortable 10 Meter Walk Test (r=0.75) and Fast 10Meter Walk Test (r=0.79) gait speed, with 56% and 62% of the variance in 6MWT gait speed explained, respectively. The regression model of 6MWT gait speed predicted by Comfortable 10 Meter Walk gait speed produced slope and intercept values near 1 and 0, respectively, especially for participants in H&Y stages II-IV. In contrast, slope and intercept values were further from 1 and 0, respectively, for the Fast 10Meter Walk Test. Comfortable 10 Meter Walk Test and 6MWT gait speeds appeared to be redundant in people with moderate to severe PD, suggesting the Comfortable 10 Meter Walk Test can be used to estimate 6MWT distance in this population.

Assistance magnitude versus metabolic cost reductions for a tethered multiarticular soft exosuit

When defining requirements for any wearable robot for walking assistance, it is important to maximize the user's metabolic benefit resulting from the exosuit assistance while limiting the metabolic penalty of carrying the system's mass. Thus, the aim of this study was to isolate and characterize the relationship between assistance magnitude and the metabolic cost of walking while also examining changes to the wearer's underlying gait mechanics. The study was performed with a tethered multiarticular soft exosuit during normal walking, where assistance was directly applied at the ankle joint and indirectly at the hip due to a textile architecture. The exosuit controller was designed such that the delivered torque profile at the ankle joint approximated that of the biological torque during normal walking. Seven participants walked on a treadmill at 1.5 meters per second under one unpowered and four powered conditions, where the peak moment applied at the ankle joint was varied from about 10 to 38% of biological ankle moment (equivalent to an applied force of 18.7 to 75.0% of body weight). Results showed that, with increasing exosuit assistance, net metabolic rate continually decreased within the tested range. When maximum assistance was applied, the metabolic rate of walking was reduced by 22.83 ± 3.17% relative to the powered-off condition (mean ± SEM).

Borg scale is valid for ratings of perceived exertion for individuals with Parkinson's disease

Parkinson's disease is a neurodegenerative disease that has traditionally been treated with anti-parkinsonian medication. There is increasing evidence that exercise is beneficial to those with PD, therefore, it is necessary to validate a measure of exertion that can be implemented across exercise settings that may not have the capability to actively monitor heart rate. The aim of this project was to determine the validity of the Borg RPE scale in individuals with PD undergoing a maximal progressive cycling exercise test. Thirty-eight males and females (58.5 ± 8.1 yrs) with a clinical diagnosis of idiopathic PD, Hoehn and Yahr stage II-III, completed a maximal exercise test. Heart rate was monitored continuously, with RPE being recorded during the last minute of each stage of the test. Correlation analysis was used to evaluate the relationship between RPE and continuous heart rate monitoring. A significant, positive correlation was present between RPE and heart rate and RPE and workload, r = 0.61 and r = 0.77 respectively. A separate mixed effects model regression analyses indicated that RPE was a significant predictor of heart rate (p < 0.001) and workload (p < 0.001). The results of a mixed effect models that RPE scores indicated that RPE values at commonly prescribed workout intensities were not associated with age, gender, or disease severity (p>0.05). Significant, positive correlation between RPE and HR indicates that the Borg category ratio scale may be used in individuals with Parkinson's disease in which formal exercise testing may not be available.

Fatigue in Parkinson's disease

Fatigue is one of the most common nonmotor symptoms in Parkinson's disease and may affect a wide range of everyday activities, cause disability and reduce quality of life. It occurs at every stage of PD, and once present will often persist and may worsen over time. Lack of a consensus of definition and classification, and a range of different self-reporting scales has so far made the study of fatigue challenging. We review a unifying taxonomy for defining fatigue in clinical and research contexts as well as case definition criteria for PD-related fatigue. The potential causes of fatigue in PD are discussed as are recommendations for treatment.

A new method to calculate external mechanical work using force-platform data in ecological situations in humans: Application to Parkinson's disease

BACKGROUND AND AIM

To accurately quantify the cost of physical activity and to evaluate the different components of energy expenditure in humans, it is necessary to evaluate external mechanical work (WEXT). Large platform systems surpass other currently used techniques. Here, we describe a calculation method for force-platforms to calculate long-term WEXT.

METHODS

Each force-platform (2.46×1.60m and 3.80×2.48m) rests on 4 piezoelectric sensors. During long periods of recording, a drift in the speed of displacement of the center of mass (necessary to calculate WEXT) is generated. To suppress this drift, wavelet decomposition is used to low-pass filter the source signal. By using wavelet decomposition coefficients, the source signal can be recovered. To check the validity of WEXT calculations after signal processing, an oscillating pendulum system was first used; then, 10 healthy subjects performed a standardized exercise (squatting exercise). A medical application is also reported in eight Parkinsonian patients during the timed "get-up and go" test and compared with the same test in ten healthy subjects.

RESULTS

Values of WEXT with the oscillating pendulum showed that the system was accurate and reliable. During the squatting exercise, the average measured WEXT was 0.4% lower than theoretical work. WEXT and mechanical work efficiency during the "get-up and go" test in Parkinson's disease patients in comparison with that of healthy subjects were very coherent.

CONCLUSIONS

This method has numerous applications for studying physical activity and mechanical work efficiency in physiological and pathological conditions.

Concerns About Falling in Parkinson's Disease: Associations with Disabilities and Personal and Environmental Factors

BACKGROUND

Fear of falling can be conceptualized in different ways, e.g., as concerns about falling or low fall-related self-efficacy. It is common in people with Parkinson's disease (PD), and there is growing knowledge about its contributing factors. However, previous multivariate studies have mainly focused on fear of falling in relation to PD-related disabilities, and less is known about the associations between fear of falling and personal and environmental factors.

OBJECTIVE

To identify explanatory factors of concerns about falling in people with PD by focusing on personal and environmental factors as well as PD-related disabilities.

METHODS

Data were collected from 241 persons with PD (39% women, median age 70 years, PD duration 8 years). Concerns about falling (assessed with the Falls Efficacy Scale-International, FES-I; categorized into low, moderate, or high concerns) were used as the dependent variable in a multivariate ordinal regression analysis. Personal factors, environmental factors and PD-related disabilities constituted independent variables.

RESULTS

Low, moderate and high concerns about falling were reported by 29% , 24% and 47% of the participants, respectively. Walking difficulties, orthostatism, motor symptoms, age, and fatigue (presented in order of importance) were significant (p <  0.05) explanatory factors of concerns about falling.

CONCLUSIONS

Several factors significantly explained concerns about falling in people with PD. Walking difficulties was by far the strongest explanatory factor. This suggests that minimizing walking difficulties should be a primary target when aiming at reducing concerns about falling in people with PD.

Mechanical Energy Recovery during Walking in Patients with Parkinson Disease

The mechanisms of mechanical energy recovery during gait have been thoroughly investigated in healthy subjects, but never described in patients with Parkinson disease (PD). The aim of this study was to investigate whether such mechanisms are preserved in PD patients despite an altered pattern of locomotion. We consecutively enrolled 23 PD patients (mean age 64±9 years) with bilateral symptoms (H&Y ≥II) if able to walk unassisted in medication-off condition (overnight suspension of all dopaminergic drugs). Ten healthy subjects (mean age 62±3 years) walked both at their 'preferred' and 'slow' speeds, to match the whole range of PD velocities. Kinematic data were recorded by means of an optoelectronic motion analyzer. For each stride we computed spatio-temporal parameters, time-course and range of motion (ROM) of hip, knee and ankle joint angles. We also measured kinetic (Wk), potential (Wp), total (WtotCM) energy variations and the energy recovery index (ER). Along with PD progression, we found a significant correlation of WtotCM and Wp with knee ROM and in particular with knee extension in terminal stance phase. Wk and ER were instead mainly related to gait velocity. In PD subjects, the reduction of knee ROM significantly diminished both Wp and WtotCM. Rehabilitation treatments should possibly integrate passive and active mobilization of knee to prevent a reduction of gait-related energetic components.

Parkinson's disease-related fatigue: A case definition and recommendations for clinical research

Fatigue is one of the most common and disabling symptoms in Parkinson's disease (PD). Since fatigue was first described as a common feature of PD 20 years ago, little progress has been made in understanding its causes or treatment. Importantly, PD patients attending the 2013 World Parkinson Congress voted fatigue as the leading symptom in need of further research. In response, the Parkinson Disease Foundation and ProjectSpark assembled an international team of experts to create recommendations for clinical research to advance this field. The working group identified several areas in which shared standards would improve research quality and foster progress including terminology, diagnostic criteria, and measurement. Terminology needs to (1) clearly distinguish fatigue from related phenomena (eg, sleepiness, apathy, depression); (2) differentiate subjective fatigue complaints from objective performance fatigability; and (3) specify domains affected by fatigue and causal factors. We propose diagnostic criteria for PD-related fatigue to guide participant selection for clinical trials and add rigor to mechanistic studies. Recommendations are made for measurement of subjective fatigue complaints, performance fatigability, and neurophysiologic changes. We also suggest areas in which future research is needed to address methodological issues and validate or optimize current practices. Many limitations in current PD-related fatigue research may be addressed by improving methodological standards, many of which are already being successfully applied in clinical fatigue research in other medical conditions (eg, cancer, multiple sclerosis). © 2016 International Parkinson and Movement Disorder Society.

Main determinants of physical activity levels in individuals with Parkinson’s disease

ABSTRACT This study analyzed the relationship between patient characteristics, factors associated with Parkinson’s disease (PD), and physical activity level of individuals affected by the disease. Forty-six volunteers with mild-to-moderate idiopathic PD were assessed using sections II/III of the Unified Parkinson’s Disease Rating Scale and their motor functions were classified according to the modified Hoehn and Yahr (HY) scale. Data such as age, disease duration, the Human Activity Profile (HAP), the Fatigue Severity Scale were collected. Lower limb bradykinesia and clinical subtypes of PD were defined. Two models that explained 76% of the variance of the HAP were used. The first comprised age, ability to perform activities of daily living (ADL), and the HY scale; the second comprised age, ability to perform ADL, and lower limb bradykinesia. Possible modifiable factors such as the ability to perform ADL and lower limb bradykinesia were identified as predictors of physical activity level of individuals with PD.

Effect of Body Composition on Walking Economy

Purpose. The aim of the study was to evaluate walking economy and physiological responses at two walking speeds in males with similar absolute body mass but different body composition. Methods. The study involved 22 young men with similar absolute body mass, BMI, aerobic performance, calf and thigh circumference. The participants differed in body composition: body fat (HBF group) and lean body mass (HLBM group). In the graded test, maximal oxygen uptake (VO

The Impact of a Portable Metabolic Measurement Device on Gait Characteristics of Older Adults With Mobility Limitations

BACKGROUND AND PURPOSE

Increased carriage loads have been found to alter gait biomechanics in young healthy adults and military personnel; however, less is known regarding the influence of added carriage load on the gait characteristics of older adults-especially those with mobility limitations. The purpose of this study was to examine spatial and temporal gait characteristics during instrumented and noninstrumented overground walking in a sample of older adults with slow gait.

METHODS

Forty older adults with slow gait completed 2 bouts of walking (instrumented and noninstrumented) over a computerized walkway during 1 clinic visit. Mean spatial-temporal characteristics, gait variability, and gait speed over 8 passes were recorded. Paired t tests and intraclass correlation coefficients were used to quantify differences.

RESULTS AND DISCUSSION

Nine of the 10 gait variables did not differ statistically between instrumented and noninstrumented gait (P < .05). Intraclass correlation coefficients (ICCs) for mean gait characteristics were excellent (range ICC = 0.94-0.98; 95% confidence interval = 0.89-0.99), and for gait variability ranged from fair to excellent (range ICC = 0.56-0.79; 95% confidence interval = 0.28-0.89). Our study was able to demonstrate no significant impact of instrumentation on gait characteristics in a sample of older adults with slow gait.

CONCLUSION

Our findings begin to fill in the gaps in the literature regarding the impact of added carriage loads on more vulnerable populations and lend support for the use of similar weighted metabolic devices as a component of gait assessment in older adults with confidence that the additional carriage-load will not significantly impact concurrent measures of gait.