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Objectives This pilot study assessed whether frontal lobe transcranial direct current stimulation (tDCS) combined with complex walking rehabilitation is feasible, safe, and shows preliminary efficacy for improving walking and executive function. Materials and methods Participants were randomized to one of the following 18-session interventions: active tDCS and rehabilitation with complex walking tasks (Active/Complex); sham tDCS and rehabilitation with complex walking tasks (Sham/Complex); or sham tDCS and rehabilitation with typical walking (Sham/Typical). Active tDCS was delivered over F3 (cathode) and F4 (anode) scalp locations for 20 min at 2 mA intensity. Outcome measures included tests of walking function, executive function, and prefrontal activity measured by functional near infrared spectroscopy. Results Ninety percent of participants completed the intervention protocol successfully. tDCS side effects of tingling or burning sensations were low (average rating less than two out of 10). All groups demonstrated gains in walking performance based on within-group effect sizes (d ≥ 0.50) for one or more assessments. The Sham/Typical group showed the greatest gains for walking based on between-group effect sizes. For executive function, the Active/Complex group showed the greatest gains based on moderate to large between-group effect sizes (d = 0.52-1.11). Functional near-infrared spectroscopy (fNIRS) findings suggest improved prefrontal cortical activity during walking. Conclusions Eighteen sessions of walking rehabilitation combined with tDCS is a feasible and safe intervention for older adults. Preliminary effects size data indicate a potential improvement in executive function by adding frontal tDCS to walking rehabilitation. This study justifies future larger clinical trials to better understand the benefits of combining tDCS with walking rehabilitation.

Objective: To assess changes in walking function and walking-related prefrontal cortical activity following two post-stroke rehabilitation interventions: an accurate adaptability (ACC) walking intervention and a steady state (SS) walking intervention. Design: Randomized, single blind, parallel group clinical trial. Setting: Hospital research setting. Subjects: Adults with chronic post-stroke hemiparesis and walking deficits. Interventions: ACC emphasized stepping accuracy and walking adaptability, while SS emphasized steady state, symmetrical stepping. Both included 36 sessions led by a licensed physical therapist. ACC walking tasks recruit cortical regions that increase corticospinal tract activation, while SS walking activates the corticospinal tract less intensely. Main measures: The primary functional outcome measure was preferred steady state walking speed. Prefrontal brain activity during walking was measured with functional near infrared spectroscopy to assess executive control demands. Assessments were conducted at baseline, post-intervention (three months), and follow-up (six months). Results: Thirty-eight participants were randomized to the study interventions (mean age 59.6 ± 9.1 years; mean months post-stroke 18.0 ± 10.5). Preferred walking speed increased from baseline to post-intervention by 0.13 ± 0.11 m/s in the ACC group and by 0.14 ± 0.13 m/s in the SS group. The Time × Group interaction was not statistically significant ( P = 0.86). Prefrontal fNIRS during walking decreased from baseline to post-intervention, with a marginally larger effect in the ACC group ( P = 0.05). Conclusions: The ACC and SS interventions produced similar changes in walking function. fNIRS suggested a potential benefit of ACC training for reducing demand on prefrontal (executive) resources during walking.

We sought to determine how people with Parkinson disease (PD) perform the sit to stand task (STS). After measuring kinetic and kinematic data our results suggest that people with PD perform the STS task by redistributing their joint torques but is accompanied with postural instability.

Walking function is compromised with older age, particularly for cognitively demanding complex walking tasks. Frontal lobe brain networks are important to both complex walking and cognitive function. There is a need for interventions that target this brain region. This pilot study assessed a novel intervention to enhance both walking and executive function in older adults. The primary hypothesis was that eighteen sessions of frontal lobe tDCS combined with complex walking rehabilitation would be feasible, safe, and show preliminary efficacy for improvements in walking and cognition. Eighteen participants were randomized to one of three intervention groups: active tDCS and rehabilitation with complex walking tasks (Active/Complex); sham tDCS and rehabilitation with complex walking tasks (Sham/Complex); or sham tDCS and rehabilitation with typical walking (Sham/Typical). Outcome measures included multiple tests of walking function, executive function, and prefrontal activity during walking measured by functional near infrared spectroscopy. For the walking tests, effect sizes for Active/Complex were generally higher than for Sham/Complex. The Sham/Typical group exhibited walking test effect sizes that were often larger than either of the complex walking groups, possibly due to higher intervention step count. For the executive function tests, effect sizes were largest for the Active/Complex group. Improvements in prefrontal activity during walking were observed, as conceptualized by the Compensation Related Utilization of Neural Circuits Hypothesis. These preliminary findings support that tDCS combined with complex walking rehabilitation in older adults is feasible and may enhance both walking function and executive function.

This pilot study assessed a novel intervention to enhance both walking and executive function in older adults. The primary hypothesis was that eighteen sessions of frontal lobe tDCS combined with walking rehabilitation would be feasible, safe, and show preliminary efficacy. Eighteen participants were randomized to one of three intervention groups: active tDCS and rehabilitation with complex walking tasks (Active/Complex); sham tDCS and rehabilitation with complex walking tasks (Sham/Complex); or sham tDCS and rehabilitation with typical walking (Sham/Typical). Outcome measures included multiple tests of walking function, executive function, and prefrontal activity during walking as measured by functional near infrared spectroscopy (fNIRS). Of the three groups, the Active/Complex group demonstrated the broadest improvements across outcome measures including for prefrontal activity. The functional range of prefrontal activity in this group was increased considerably, as conceptualized by the Compensation Related Utilization of Neural Circuits Hypothesis. Frontal tDCS is a promising adjuvant to walking rehabilitation.

Background: Functional near-infrared spectroscopy (fNIRS) is a valuable neuroimaging approach for studying cortical contributions to walking function. Recruitment of prefrontal cortex during walking has been a particular area of focus in the literature. The present study investigated whether task-related change in prefrontal recruitment measured by fNIRS is affected by individual differences in people post-stroke. The primary hypotheses were that poor mobility function would contribute to prefrontal over-recruitment during typical walking, and that poor cognitive function would contribute to a ceiling in prefrontal recruitment during dual-task walking (i.e., walking with a cognitive task). Methods: Thirty-three adults with chronic post-stroke hemiparesis performed three tasks: typical walking at preferred speed (Walk), serial-7 subtraction (Serial7), and walking combined with serial-7 subtraction (Dual-Task). Prefrontal recruitment was measured with fNIRS and quantified as the change in oxygenated hemoglobin concentration (ΔO2Hb) between resting and active periods for each task. Spatiotemporal gait parameters were measured on an electronic walkway. Stepwise regression was used to assess how prefrontal recruitment was affected by individual differences including age, sex, stroke region, injured hemisphere, stroke chronicity, 10-meter walking speed, balance confidence measured by Activities-specific Balance Confidence (ABC) Scale, sensorimotor impairment measured by Fugl-Meyer Assessment, and cognitive function measured by Mini-Mental State Examination (MMSE). Results: For Walk, poor balance confidence (ABC Scale score) significantly predicted greater prefrontal recruitment (ΔO2Hb; R2 = 0.25, p = 0.003). For Dual-Task, poor cognitive function (MMSE score) significantly predicted lower prefrontal recruitment (ΔO2Hb; R2 = 0.25, p = 0.002). Conclusions: Poor mobility function predicted higher prefrontal recruitment during typical walking, consistent with compensatory over-recruitment. Poor cognitive function predicted lower prefrontal recruitment during dual-task walking, consistent with a recruitment ceiling effect. These findings indicate that interpretation of prefrontal recruitment should carefully consider the characteristics of the person and demands of the task.

Background and purpose Adequate lower limb strength and motor control are essential for mobility and quality of life. People with Parkinson disease (PD) experience a significant and progressive decline in motor capabilities as part of this neurodegenerative disease. The primary objective of this study was to examine the effect of PD on (1) muscular strength and (2) force steadiness in muscles that are primarily responsible for locomotion and stability. Methods Thirteen persons with PD and 13 healthy age-matched controls participated. Participants performed maximal and submaximal (5%, 10%, and 20% maximum voluntary contractions) isometric force tasks with the limb stabilized in a customized device. Strength of the hip extensors and flexors, hip abductors and adductors, and ankle plantar flexors and dorsiflexors was quantified based on data obtained from force transducers, with the relevant joint stabilized in standardized positions. Results Individuals with PD were weaker and exhibited higher amounts of force variability than controls across the lower extremity. Reduced strength was greatest in the hip flexors (2.0 N/kg vs 2.6 N/kg) and ankle plantar flexors (1.74 N/kg vs 2.64 N/kg) and dorsiflexors (1.9 N/kg vs 2.3 N/kg). Force steadiness was impaired in the hip flexors, ankle plantar flexors, and dorsiflexors. Discussion and conclusions Reduced maximal force production was concomitant with impaired force control within the muscles that are critical for effective ambulation (hip flexion, ankle dorsiflexion, and ankle plantar flexion). These features should be evaluated when considering contributors to reduced mobility and quality of life.Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A241).

Muscular weakness and the motor difficulties associated with Parkinson disease (PD) often impair the performance of activities of daily living (ADL). However, little is known about the magnitude and distribution of relative muscular effort of persons with PD during ADL. The purpose of this investigation was to determine the relative magnitude of lower extremity moment production that persons with PD use to perform common ADL.Fifteen participants with mild-to-moderate PD and 14 age/sex-matched controls volunteered. Participants performed a series of ADL tasks, as follows: gait initiation (GI), gait, and stair ascending tasks. Participants were then asked to perform maximal-effort isokinetic tests of hip and knee extension and ankle plantarflexion at speeds of 90° per second and 120° per second. Relative effort was quantified as a percentage of the maximal isokinetic value produced by a joint during performance of the ADL. Relative effort and peak isokinetic joint moments were analyzed using a mixed-model ANOVA with repeated measures. All other comparisons were evaluated using independent t-tests.Persons with PD produced smaller ankle plantarflexion moment at both 90° per second and 120° per second (P0.05). Relative effort during GI (271% vs 189%, P0.05) and gait (270% vs 161%, P0.05) was significantly greater at the ankle in persons with PD. Contribution of the ankle to the support moment was lower in PD during stair ascending (24% vs 34%) and GI (63% vs 57%) compared with that in controls.The reduced ankle moments during ADL are indicative of deficits in muscular capabilities in those with PD. Moreover, PD caused a redistribution of joint torques, such that PD participants used their hip extensors more and ankle plantarflexors less.

Progressive supranuclear palsy (PSP) is the most common form of atypical Parkinsonism; however it is underdiagnosed and often misdiagnosed as Parkinson's disease (PD).We investigated gait initiation (GI) and gait performance in a total of 36 participants (12 PSP, 12 PD and 12 healthy age- and gender-matched controls) to gain further insight into specific motor deficits that characterize dynamic postural control and gait in PSP. Anticipatory postural adjustments (APAs), quantified by center of pressure (COP) displacement and speed prior to an initial heel off, and the maximum distance (COPCOM) between COP and center of mass (COM) during all three GI phases were calculated to evaluate dynamic postural control. Steady-state gait performance was also evaluated and compared across the groups.APAs in PSP were significantly altered such that the posterior COP shift is profoundly diminished when compared to PD (p 0.05). Moreover, proper velocity control during GI in PSP was affected, particularly in the mediolateral direction, when compared to PD (p 0.05). The diminished COPCOM distance is further indicative of more severe dynamic postural instability in PSP than in PD (p 0.05). Significant differences in spatiotemporal parameters, inter-step variability, and asymmetry during gait in PSP, in comparison with PD were also identified (all p's 0.05).The present study reveals that the compensatory GI strategy in PSP is distinct from PD and paradoxically induces lateral instability. Further, gait performance in PSP is slower and more variable which could be the consequence of lateral instability and fear of falling.

Parkinson disease is a progressive neurodegenerative disorder characterized by a variety of motor and nonmotor features. This article reviews the problems of postural instability and gait disturbance in persons with Parkinson disease through the discussion of (1) the neuropathology of parkinsonian motor deficits, (2) behavioral manifestations of gait and postural abnormalities observed in persons with Parkinson disease, and (3) pharmacologic, surgical, and physical therapy-based interventions to combat postural instability and gait disturbance. This article advances the treatment of postural instability and gait disturbance by condensing up-to-date knowledge and making it available to clinicians and rehabilitation professionals.

Bradykinesia is a prominent problem for persons with Parkinson's disease (PD) and has been studied extensively with upper extremity tasks; however there is a lack of research examining bradykinesia in targeted lower extremity tasks related to mobility. Navigating steps and curbs are challenging tasks for older adults and neurologically impaired and thus utilizing these behaviors provides ecological validity to the study of bradykinesia. Herein we assess differences in step negotiation performance between individuals with PD and aged matched older adults. Three-dimensional kinematics and ground reaction forces were collected while 12 participants with PD and 12 older adults performed a single step up onto a platform. Persons with PD spent a significantly greater amount of time in the heel lift phase (P=0.0003, d=1.80). Peak vertical foot velocity of the lead foot was also significantly less in PD (P=0.02, d=1.05). Lastly, persons with PD displayed reduced sagittal hip and knee range of motion during the trail step (P=0.01, d=1.20 and P=0.02, d=1.05, respectively). Parkinson's participants exhibited slight decrement in step negotiation execution. Increased step time and decreased foot velocity and range of motion were attributes associated with Parkinson's step negotiation performance. Contrary to our hypothesis, in many comparisons, persons with PD during their best medicated state performed comparable to older adults, indicative of successful pharmacotherapy. Rehabilitation efforts can seek to improve performance in motor control tasks such as step negotiation, by restoring the relationship between perceived and actual motor output and enhancing muscle coordination and output as well as ranges of motion.