Natural Walking Intensity in Persons With Parkinson Disease.

BACKGROUND AND PURPOSE: Few persons with Parkinson disease (PD) appear to engage in moderate-intensity walking associated with disease-modifying health benefits. How much time is spent walking at lower, yet still potentially beneficial, intensities is poorly understood. The purpose of this exploratory, observational study was to describe natural walking intensity in ambulatory persons with PD. METHODS: Accelerometer-derived real-world walking data were collected for more than 7 days at baseline from 82 participants enrolled in a PD clinical trial. Walking intensity was defined according to the number of steps in each active minute (1-19, 20-39, 40-59, 60-79, 80-99, or ≥100 steps). Daily minutes of walking and duration of the longest sustained walking bout were calculated at each intensity. Number of sustained 10 to 19, 20 to 29, and 30-minute bouts and greater at any intensity also were calculated. Values were analyzed in the context of physical activity guidelines. RESULTS: Most daily walking occurred at lower intensities (157.3 ± 58.1 min of 1-19 steps; 81.3 ± 32.6 min of 20-39 steps; 38.2 ± 21.3 min of 40-59 steps; 15.1 ± 11.5 min of 60-79 steps; 7.4 ± 7.0 min of 80-99 steps; 7.3 ± 9.6 min of ≥100 steps). The longest daily sustained walking bout occurred at the lowest intensity level (15.9 ± 5.2 min of 1-19 steps). Few bouts lasting 20 minutes and greater occurred at any intensity. DISCUSSION AND CONCLUSIONS: Despite relatively high daily step counts, participants tended to walk at remarkably low intensity, in bouts of generally short duration, with relatively few instances of sustained walking. The findings reinforced the need for health promotion interventions designed specifically to increase walking intensity.Video Abstract available for more insight from authors (see the Video, Supplemental Digital Content 1 available at: http://links.lww.com/JNPT/A426 ).

Are Mobile Persons With Parkinson Disease Necessarily More Active?

BACKGROUND AND PURPOSE: Walking activity in persons with Parkinson disease (PD) is important for preventing functional decline. The contribution of walking activity to home and community mobility in PD is poorly understood. METHODS: Cross-sectional baseline data (N = 69) were analyzed from a randomized controlled PD trial. The Life-Space Assessment (LSA) quantified the extent, frequency, and independence across 5 expanding levels of home and community mobility, producing individual subscores and a total score. Two additional summed scores were used to represent mobility within (Levels 1-3) and beyond (Levels 4-5) neighborhood limits. An accelerometer measured walking activity for 7 days. Regression and correlation analyses evaluated relationships between daily steps and mobility scores. Mann-Whitney U tests secondarily compared differences in mobility scores between the active and sedentary groups. RESULTS: Walking activity contributed significantly to the summed Level 1-3 score (ß = 0.001, P = 0.004) but not to the summed Level 4-5 (ß = 0.001, P = 0.33) or total (ß = 0.002, P = 0.07) scores. Walking activity was significantly related to Level 1 (ρ = 0.336, P = 0.005), Level 2 (ρ = 0.307, P = 0.010), and Level 3 (ρ = 0.314, P = 0.009) subscores. Only the summed Level 1-3 score (P = 0.030) was significantly different between the active and sedentary groups. DISCUSSION AND CONCLUSIONS: Persons with PD who demonstrated greater mobility beyond the neighborhood were not necessarily more active; walking activity contributed more so to home and neighborhood mobility. Compared with LSA total score, the Level 1-3 summed score may be a more useful participation-level measure for assessing the impact of changes in walking activity.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1 available at: http://links.lww.com/JNPT/A349).

Design of the WHIP-PD study: a phase II, twelve-month, dual-site, randomized controlled trial evaluating the effects of a cognitive-behavioral approach for promoting enhanced walking activity using mobile health technology in people with Parkinson-disease.

BACKGROUND: Parkinson disease (PD) is a debilitating and chronic neurodegenerative disease resulting in ambulation difficulties. Natural walking activity often declines early in disease progression despite the relative stability of motor impairments. In this study, we propose a paradigm shift with a "connected behavioral approach" that targets real-world walking using cognitive-behavioral training and mobile health (mHealth) technology. METHODS/DESIGN: The Walking and mHealth to Increase Participation in Parkinson Disease (WHIP-PD) study is a twelve-month, dual site, two-arm, randomized controlled trial recruiting 148 participants with early to mid-stage PD. Participants will be randomly assigned to connected behavioral or active control conditions. Both conditions will include a customized program of goal-oriented walking, walking-enhancing strengthening exercises, and eight in-person visits with a physical therapist. Participants in the connected behavioral condition also will (1) receive cognitive-behavioral training to promote self-efficacy for routine walking behavior and (2) use a mHealth software application to manage their program and communicate remotely with their physical therapist. Active control participants will receive no cognitive-behavioral training and manage their program on paper. Evaluations will occur at baseline, three-, six-, and twelve-months and include walking assessments, self-efficacy questionnaires, and seven days of activity monitoring. Primary outcomes will include the change between baseline and twelve months in overall amount of walking activity (mean number of steps per day) and amount of moderate intensity walking activity (mean number of minutes per day in which > 100 steps were accumulated). Secondary outcomes will include change in walking capacity as measured by the six-minute walk test and ten-meter walk test. We also will examine if self-efficacy mediates change in amount of walking activity and if change in amount of walking activity mediates change in walking capacity. DISCUSSION: We expect this study to show the connected behavioral approach will be more effective than the active control condition in increasing the amount and intensity of real-world walking activity and improving walking capacity. Determining effective physical activity interventions for persons with PD is important for preserving mobility and essential for maintaining quality of life. Clinical trials registration NCT03517371, May 7, 2018. TRIAL REGISTRATION: ClinicalTrials.gov: NCT03517371. Date of registration: May 7, 2018. Protocol version: Original.

Multifractality, Interactivity, and the Adaptive Capacity of the Human Movement System: A Perspective for Advancing the Conceptual Basis of Neurologic Physical Therapy.

BACKGROUND AND PURPOSE: Physical therapists seek to optimize movement as a means of reducing disability and improving health. The short-term effects of interventions designed to optimize movement ultimately are intended to be adapted for use across various future patterns of behavior, in potentially unpredictable ways, with varying frequency, and in the context of multiple tasks and environmental conditions. In this perspective article, we review and discuss the implications of recent evidence that optimal movement variability, which previously had been associated with adaptable motor behavior, contains a specific complex nonlinear feature known as "multifractality." SUMMARY OF KEY POINTS: Multifractal movement fluctuation patterns reflect robust physiologic interactivity occurring within the movement system across multiple time scales. Such patterns provide conceptual support for the idea that patterns of motor behavior occurring in the moment are inextricably linked in complex, physiologic ways to patterns of motor behavior occurring over much longer periods. The human movement system appears to be particularly tuned to multifractal fluctuation patterns and exhibits the ability to reorganize its output in response to external stimulation embedded with multifractal features. RECOMMENDATIONS FOR CLINICAL PRACTICE: As a fundamental feature of human movement, multifractality opens new avenues for conceptualizing the link between physiologic interactivity and adaptive capacity. Preliminary evidence supporting the positive influence of multifractal rhythmic auditory stimulation on the gait patterns of individuals with Parkinson disease is used to illustrate how physical therapy interventions might be devised to specifically target the adaptive capacity of the human movement system.Video Abstract available for more insights from the authors (see Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A183).

Exploring the Effects of Using an Oral Appliance to Reduce Movement Dysfunction in an Individual With Parkinson Disease: A Single-Subject Design Study.

BACKGROUND AND PURPOSE: Clinical reports suggest that wearing an oral appliance can improve the gait and balance of an individual with Parkinson disease (PD). Our primary purpose was to systematically explore this effect using a single-subject study design and quantitative motion analysis. Secondarily, we sought to examine the quality-of-life outcomes following 1-month of routine oral appliance wear. METHODS: The participant was a 73-year-old ambulatory man with mid-stage PD. Using an A-B-A design, for which a custom-made oral appliance served as the intervention, kinematic and kinetic data were captured during performance of Four Square Step Test, serpentine walk, and tandem walk tasks. Grip strength was quantified with a dynamometer. Quality-of-life outcomes were collected after 1 month of appliance wear using the Parkinson Disease Questionnaire-39 (PDQ-39). Perceived changes in balance, mobility, and quality of life were captured from the participant using an 11-point Global Rate of Change (GRC) scale. RESULTS: Changes in mobility, postural control, and grip strength during appliance wear were suggestive of reduced movement dysfunction. The PDQ-39 revealed a significant improvement in quality of life, primarily related to increased emotional well-being, decreased stigma, and increased communication. GRC scores indicated a clinically significant improvement in ease of movement in the community (+3), ease of movement during the performance of activities of daily living (+4), and in standing balance while performing activities of daily living (+4). DISCUSSION AND CONCLUSIONS: Study findings provided quantitative evidence supporting the effectiveness of oral appliance wear for reducing movement dysfunction in a patient with mid-stage PD.Video Abstract available for more insights from the authors (see Supplemental Digital Content 1, http://links.lww.com/JNPT/A155).

Two-Year Trajectory of Fall Risk in People With Parkinson Disease: A Latent Class Analysis.

OBJECTIVE: To examine fall risk trajectories occurring naturally in a sample of individuals with early to middle stage Parkinson disease (PD). DESIGN: Latent class analysis, specifically growth mixture modeling (GMM), of longitudinal fall risk trajectories. SETTING: Assessments were conducted at 1 of 4 universities. PARTICIPANTS: Community-dwelling participants with PD of a longitudinal cohort study who attended at least 2 of 5 assessments over a 2-year follow-up period (N=230). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Fall risk trajectory (low, medium, or high risk) and stability of fall risk trajectory (stable or fluctuating). Fall risk was determined at 6 monthly intervals using a simple clinical tool based on fall history, freezing of gait, and gait speed. RESULTS: The GMM optimally grouped participants into 3 fall risk trajectories that closely mirrored baseline fall risk status (P=.001). The high fall risk trajectory was most common (42.6%) and included participants with longer and more severe disease and with higher postural instability and gait disability (PIGD) scores than the low and medium fall risk trajectories (P<.001). Fluctuating fall risk (posterior probability <0.8 of belonging to any trajectory) was found in only 22.6% of the sample, most commonly among individuals who were transitioning to PIGD predominance. CONCLUSIONS: Regardless of their baseline characteristics, most participants had clear and stable fall risk trajectories over 2 years. Further investigation is required to determine whether interventions to improve gait and balance may improve fall risk trajectories in people with PD.

Life-Space Assessment and Physical Activity Scale for the Elderly: validity of proxy informant responses.

OBJECTIVE: To validate the administration of the Life-Space Assessment (LSA) and Physical Activity Scale for the Elderly (PASE) surveys to proxy informants, as would be necessary when measuring long-term outcomes in acutely ill, hospitalized older adults who are initially incapacitated but eventually return to the community. DESIGN: Cross-sectional study. SETTING: General community. PARTICIPANTS: Convenience sample of dyads (N=40) composed of an ambulatory older adult and a familiar companion. INTERVENTIONS: Dyads completed the LSA and PASE surveys on 1 occasion. Companions based their responses on the recent mobility and physical activity of the older adult. MAIN OUTCOME MEASURES: Paired total scores for each instrument. RESULTS: At a group level, the difference between older adult and companion mean scores for each instrument was not significant (P>.05). Standardized mean difference values were small (d<0.1). Paired scores were significantly yet moderately associated: intraclass correlation coefficient(1,1)=.84 to .88; P<.01. Difference in scores was not associated with time spent together (P>.05) or older adult gait speed (P>.05). At an individual level, older adults and companions agreed more closely on the LSA than on the PASE. However, disagreement in excess of estimated measurement error occurred in 40% of the dyads for the LSA and in none of the dyads for the PASE. CONCLUSIONS: Older adults and companions collectively provided similar responses on each instrument. Nonetheless, varying levels of agreement within individual dyads suggested that proxy responses should be considered carefully. Implications for clinical research and practice research are discussed.

Differential effects of cardiovascular and resistance exercise on functional mobility in individuals with advanced cancer: a randomized trial.

OBJECTIVE: To compare the effects of resistance and cardiovascular exercise on functional mobility in individuals with advanced cancer. DESIGN: Prospective, 2-group pretest-posttest pilot study with randomization to either resistance or cardiovascular exercise mode. SETTING: Comprehensive community cancer center and a hospital-based fitness facility. PARTICIPANTS: Volunteer sample of individuals (N=66; 30 men; 36 women; mean age, 62y) with advanced cancer recruited through the cancer center, palliative care service, rehabilitation department, and a local hospice. INTERVENTIONS: Ten weeks of individualized resistance or cardiovascular exercise, prescribed and monitored by oncology-trained exercise personnel. MAIN OUTCOME MEASURES: Functional mobility was assessed using the Short Physical Performance Battery (SPPB); self-reported pain and fatigue were assessed secondarily using visual analog scales. Data were analyzed using a split plot 2×2 analysis of variance (α=.05). RESULTS: Fifty-two patients (78.8%) completed the study: 23 (67.7%) of 34 patients in the resistance arm and 29 (90.6%) of 32 patients in the cardiovascular arm. No participant withdrew because of study adverse events. Ten-week outcomes (n=52) included a significant increase in SPPB total score (P<.001), increase in gait speed (P=.001), and reduction in fatigue (P=.05). Although cardiovascular exercise participants had a modestly greater improvement in SPPB total score than resistance training participants (F1,49=4.21, P=.045), the difference was not confirmed in a subsequent intention-to-treat analysis (N=66). CONCLUSIONS: Individuals with advanced cancer appear to benefit from exercise for improving functional mobility. Neither resistance nor cardiovascular exercise appeared to have a strong differential effect on outcome.

Narrowing the physiotherapy knowledge-practice gap: faculty training beyond the health sciences.

Physiotherapists seek to improve client movement and promote function within an individual's unique environmental and social realities. Despite this intention, there is a well-noted knowledge-practice gap, that is, therapists generally lack sufficient foundational preparation to effectively navigate societal challenges impacting contemporary healthcare. As one step toward addressing the issue, we propose an educational solution targeting current and future physiotherapy faculty, whose responsibilities for entry-level course development and curriculum design substantially impact student readiness for clinical practice. We propose that physiotherapy faculty trained via postprofessional education in a non-biomedical field (e.g. psychology, education, and philosophy) will be uniquely prepared to provide students with tools for dealing with complex social issues facing their clients; critical analysis skills; statistical and technological training; and a deeper theoretical and philosophical understanding of practice. Taken together, such interdisciplinary tools could help address the knowledge-practice gap for physiotherapists and promote the ongoing evolution of the profession in concert with contemporary healthcare. Physiotherapists who pursue interdisciplinary studies may more deeply understand the challenges faced by clinicians and may be well-positioned to leverage knowledge and methods in another scientific discipline to expand and transform the scope of solutions to these challenges.

Feasibility and Proof-of-Concept of Delivering an Autonomous Music-Based Digital Walking Intervention to Persons with Parkinson's Disease in a Naturalistic Setting.

BACKGROUND: Reduced motor automaticity in Parkinson's disease (PD) negatively impacts the quality, intensity, and amount of daily walking. Rhythmic auditory stimulation (RAS), a clinical intervention shown to improve walking outcomes, has been limited by barriers associated with the need for ongoing clinician input. OBJECTIVE: To assess the feasibility, proof-of-concept, and preliminary clinical outcomes associated with delivering an autonomous music-based digital walking intervention based on RAS principles to persons with PD in a naturalistic setting. METHODS: Twenty-three persons with PD used the digital intervention independently for four weeks to complete five weekly 30-minute sessions of unsupervised, overground walking with music-based cues. The intervention progressed autonomously according to real-time gait sensing. Feasibility of independent use was assessed by examining participant adherence, safety, and experience. Intervention proof-of-concept was assessed by examining spatiotemporal metrics of gait quality, daily minutes of moderate intensity walking, and daily steps. Preliminary clinical outcomes were assessed following intervention completion. RESULTS: Participants completed 86.4% of sessions and 131.1% of the prescribed session duration. No adverse events were reported. Gait speed, stride length, and cadence increased within sessions, and gait variability decreased (p < 0.05). Compared to baseline, increased daily moderate intensity walking (mean Δ= +21.44 minutes) and steps (mean Δ= +3,484 steps) occurred on designated intervention days (p < 0.05). Quality of life, disease severity, walking endurance, and functional mobility were improved after four weeks (p < 0.05). CONCLUSIONS: Study findings supported the feasibility and potential clinical utility of delivering an autonomous digital walking intervention to persons with PD in a naturalistic setting.

Capturing ambulatory activity decline in Parkinson's disease.

BACKGROUND AND PURPOSE: Relatively little is known about the natural evolution of physical activity-related participation restrictions associated with Parkinson's disease (PD). We examined this issue prospectively, using continuous monitoring technology to capture the free-living ambulatory activity of persons with PD engaging in life situations. We specifically sought (1) to explore natural, long-term changes in daily ambulatory activity and (2) to compare the responsiveness of ambulatory activity parameters to clinical measures of gait and disease severity. METHODS: Thirty-three persons with PD participated (Hoehn and Yahr range of 1-3). Participants wore a step activity monitor for up to 7 days at baseline and again at 1-year follow-up. Mean daily values were calculated for parameters indicative of amount, intensity, frequency, and duration of ambulatory activity. Clinical measures included the Unified Parkinson Disease Rating Scale, the 6-Minute Walk, and Maximal Gait Speed. Parametric tests for paired samples were used to investigate changes in ambulatory activity parameters and clinical measures. RESULTS: Participants had significant declines in the amount and intensity of daily ambulatory activity but not in its frequency and duration (P < 0.007). Declines occurred in the absence of changes in clinical measures of gait or disease severity. The greatest 1-year decline occurred in the number of daily minutes participants spent engaging in at least moderate-intensity ambulatory activity. CONCLUSION: Continuous monitoring of ambulatory activity beyond mere step counts may serve as a distinct and important means of quantifying declining ambulatory behavior associated with disease progression or improved ambulatory behavior resulting from rehabilitation and medical and/or surgical interventions in persons with PD.

Does clinically measured walking capacity contribute to real-world walking performance in Parkinson's disease?

OBJECTIVE: The study examined how clinically measured walking capacity contributes to real-world walking performance in persons with Parkinson's disease (PD). METHODS: Cross-sectional baseline data (n = 82) from a PD clinical trial were analyzed. The 6-Minute Walk Test (6MWT) and 10-Meter Walk Test (10MWT) were used to generate capacity metrics of walking endurance and fast gait speed, respectively. An activity monitor worn for seven days was used to generate performance metrics of mean daily steps and weekly moderate intensity walking minutes. Univariate linear regression analyses were used to examine associations between each capacity and performance measure in the full sample and less and more active subgroups. RESULTS: Walking capacity significantly contributed to daily steps in the full sample (endurance: R2=.13, p < .001; fast gait speed: R2=.07, p = .017) and in the less active subgroup (endurance: R2 =.09, p = .045). Similarly, walking capacity significantly contributed to weekly moderate intensity minutes in the full sample (endurance: R2=.13, p < .001; fast gait speed: R2=.09, p = .007) and less active subgroup (endurance: R2 = .25, p < .001; fast gait speed: R2 =.21, p = .007). Walking capacity did not significantly contribute to daily steps or moderate intensity minutes in the more active subgroup. CONCLUSIONS: Walking capacity contributed to, but explained a relatively small portion of the variance in, real-world walking performance. The contribution was somewhat greater in less active individuals. The study adds support to the idea that clinically measured walking capacity may have limited benefit for understanding real-world walking performance in PD. Factors beyond walking capacity may better account for actual walking behavior.

Ambulatory activity in individuals with multiple sclerosis.

BACKGROUND AND PURPOSE: Specific characteristics of physical activity limitations associated with multiple sclerosis (MS) remain unclear. Our purpose was to examine the impact of MS disability on physical activity behaviors involving ambulation. We also explored relationships among ambulatory activity parameters and clinical measures of gait, balance, and fatigue. METHODS: Twenty-one adults with MS participated: 11 without ambulatory limitation (Expanded Disability Status Scale [EDSS] score ≤ 4.5) and 10 with ambulatory limitation (EDSS score > 4.5). Participants wore a step activity monitor for up to 7 days. Daily values were calculated for parameters indicative of (1) overall activity, (2) upper limits of activity output, and (3) activity work-rest cycles. Clinical measures included Multiple Sclerosis Walking Scale, Timed 25-Foot Walk, Timed Up and Go test, 6-Minute Walk, Dynamic Gait Index, Berg Balance Scale, Activities-specific Balance Confidence Scale, and Modified Fatigue Impact Scale. Statistical analyses were conducted using nonparametric tests. RESULTS: Participants without limitation were more active, demonstrated higher upper limits of activity output, and had longer activity bouts than participants with limitation (P < 0.05). Only 1 participant averaged more than 100 steps per minute over a 30-minute period. Of the ambulatory activity parameters, daily step count was most strongly related to gait and balance measures. Of the clinical measures, EDSS and Multiple Sclerosis Walking Scale scores were most strongly related to daily step count. CONCLUSION: Individuals with MS are not necessarily sedentary, but few may achieve recommended daily physical activity levels. Ambulatory activity characteristics revealed new insights into physical activity limitations in MS. The study findings suggest that disability status should direct physical activity interventions.

Charting the progression of disability in Parkinson disease: study protocol for a prospective longitudinal cohort study.

BACKGROUND: People with Parkinson disease (PD), even in the presence of symptomatic relief from medical, surgical, and rehabilitative interventions, face a persistent worsening of disability. This disability is characterized by diminished quality of life, reduced functional mobility, declining performance in activities of daily living and worsening neurological impairments. While evidence has emerged supporting the clinically meaningful benefits of short-term exercise programs on these underlying factors, assertions regarding the effects of sustained programs of exercise and physical activity on the trajectory of disablement in PD are made in the absence of direct evidence. Indeed, the natural decline in quality of life and functional mobility in people diagnosed with PD is poorly understood. Moreover, outcome measures commonly used in clinical exercise trials typically do not capture the full spectrum of disability as defined by the World Health Organization (WHO). METHODS/DESIGN: The objective of this multicenter prospective study will be to examine the 2-year trajectory of disablement in a cohort of persons with PD. Two hundred sixty participants will be recruited to produce an expected final sample size of 150 individuals. Participants will be included if they are greater than 40 years of age, have a neurologist confirmed diagnosis of idiopathic PD, and are at Hoehn and Yahr stages 1 through 4. Data will be collected every 6 months during the study period. Primary outcome measures reflecting a broad spectrum of disablement will include, but will not be limited to, MDS-UPDRS, Timed Up and Go, Berg Balance Test, Nine Hole Peg Test, PDQ-39, and directly monitored ambulatory activity. Self-reported exercise and physical activity data also will be recorded. Statistical analyses will be used to characterize the trajectory of disablement and examine the influence of its underlying contributing factors. DISCUSSION: Tertiary prevention is an important component of contemporary healthcare for individuals living with degenerative disease. For individuals with PD, there is growing recognition that exercise and/or physical activity efforts to slow the rate of functional mobility decline, in particular, may be critical for optimizing quality of life. By describing the natural trajectory of disablement, exercise habits, and physical activity in a cohort of persons with PD, this investigation will establish an important foundation for future intervention research. Specifically, through the evaluation of the influence of sustained exercise and physical activity on disablement, the study will serve as a preliminary step toward developing a randomized controlled trial of long-term exercise in persons with PD.

Comparative Effectiveness of mHealth-Supported Exercise Compared With Exercise Alone for People With Parkinson Disease: Randomized Controlled Pilot Study.

Background: Declining physical activity commonly occurs in people with Parkinson disease (PD) and contributes to reduced functional capacity and quality of life. Objective: The purpose of this study was to explore the preliminary effectiveness, safety, and acceptability of a mobile health (mHealth)-mediated exercise program designed to promote sustained physical activity in people with PD. Design: This was a 12-month single-blind (assessor), pilot, comparative-effectiveness, randomized controlled study. Methods: An mHealth-mediated exercise program (walking with a pedometer plus engagement in planned exercise supported by a mobile health application) was compared over 1 year with an active control condition (walking with a pedometer and exercise only). There were 51 participants in a community setting with mild-to-moderately severe (Hoehn and Yahr stages 1-3) idiopathic PD. Daily steps and moderate-intensity minutes were measured using a step activity monitor for 1 week at baseline and again at 12 months. Secondary outcomes included the 6-Minute Walk Test, Parkinson Disease Questionnaire 39 mobility domain, safety, acceptability, and adherence. Results: Both groups increased daily steps, moderate-intensity minutes, and 6-Minute Walk Test, with no statistically significant between-group differences observed. In the less active subgroup, changes in daily steps and moderate-intensity minutes were clinically meaningful. An improvement in the Parkinson Disease Questionnaire 39 mobility score favored mHealth in the overall comparison and was statistically and clinically meaningful in the less active subgroup. Limitations: The limitation of the current study was the small sample size. Conclusions: Both groups improved physical activity compared with expected activity decline over 1 year. The addition of the mHealth app to the exercise intervention appeared to differentially benefit the more sedentary participants. Further study in a larger group of people with low activity at baseline is needed.

Using step activity monitoring to characterize ambulatory activity in community-dwelling older adults.

OBJECTIVES: To explore the potential of using step activity monitoring to detect differences in ambulatory activity associated with advancing age and declining function in community-dwelling seniors. DESIGN: Cross-sectional pilot study. SETTING: General communities of Seattle, Washington; Catonsville, Maryland; and Durham, North Carolina. PARTICIPANTS: Thirty healthy younger adults, 28 healthy older adults, and 12 older adults reporting functional limitations. MEASUREMENTS: Ambulatory activity data were collected over 6 days with the StepWatch 3. Average daily values were calculated for number of steps, number of minutes of activity, number of activity bouts, variability of minute-to-minute activity, and randomness of minute-to-minute activity fluctuations. RESULTS: Healthy older adults engaged in fewer bouts of activity (P=.03) and displayed less-variable activity (P=.02) than younger adults. Older adults reporting functional limitations not only engaged in fewer bouts of activity (P=.009) and less variable activity (P<.001) than younger adults, but also accumulated fewer total steps (P=.003) and minutes of activity (P=.008) and had less-random minute-to-minute activity fluctuations (P=.02). CONCLUSION: Step activity monitoring data were useful for detecting differences in ambulatory activity according to age and functional limitation. Monitor-based measures reflecting patterns of ambulatory activity show promise for use in studies of physical functioning.

Approximate entropy detects the effect of a secondary cognitive task on postural control in healthy young adults: a methodological report.

BACKGROUND: Biomechanical measures of postural stability, while generally useful in neuroscience and physical rehabilitation research, may be limited in their ability to detect more subtle influences of attention on postural control. Approximate entropy (ApEn), a regularity statistic from nonlinear dynamics, recently has demonstrated relatively good measurement precision and shown promise for detecting subtle change in postural control after cerebral concussion. Our purpose was to further explore the responsiveness of ApEn by using it to evaluate the immediate, short-term effect of secondary cognitive task performance on postural control in healthy, young adults. METHODS: Thirty healthy, young adults performed a modified version of the Sensory Organization Test featuring single (posture only) and dual (posture plus cognitive) task trials. ApEn values, root mean square (RMS) displacement, and equilibrium scores (ES) were calculated from anterior-posterior (AP) and medial-lateral (ML) center of pressure (COP) component time series. For each sensory condition, we compared the ability of the postural control parameters to detect an effect of cognitive task performance. RESULTS: COP AP time series generally became more random (higher ApEn value) during dual task performance, resulting in a main effect of cognitive task (p = 0.004). In contrast, there was no significant effect of cognitive task for ApEn values of COP ML time series, RMS displacement (AP or ML) or ES. CONCLUSION: During dual task performance, ApEn revealed a change in the randomness of COP oscillations that occurred in a variety of sensory conditions, independent of changes in the amplitude of COP oscillations. The finding expands current support for the potential of ApEn to detect subtle changes in postural control. Implications for future studies of attention in neuroscience and physical rehabilitation are discussed.

Adaptation of postural recovery responses to a vestibular sensory illusion in individuals with Parkinson disease and healthy controls.

BACKGROUND: The ability to adapt postural responses to sensory illusions diminishes with age and is further impaired by Parkinson disease. However, limited information exists regarding training-related adaptions of sensory reweighting in these populations. METHODS: This study sought to determine whether Parkinson disease or age would differentially affect acute postural recovery or adaptive postural responses to novel or repeated exposure to sensory illusions using galvanic vestibular stimulation during quiet stance. FINDINGS: Acutely, individuals with Parkinson disease demonstrated larger center of pressure coefficient of variation compared to controls. Unlike individuals with Parkinson disease and asymptomatic older adults, healthy young adults acutely demonstrated a reduction in Sample Entropy to the sensory illusion. Following a period of consolidation Sample Entropy increased in the healthy young group, which coincided with a decreased center of pressure coefficient of variation. Similar changes were not observed in the Parkinson disease or older adult groups. INTERPRETATION: Taken together, these results suggest that young adults learn to adapt to vestibular illusion in a more robust manner than older adults or those with Parkinson disease. Further investigation into the nature of this adaptive difference is warranted.

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.

Recovery of postural control after cerebral concussion: new insights using approximate entropy.

CONTEXT: The return-to-play decision after sport-related cerebral concussion depends in part on knowing when an athlete has fully recovered postural control after injury. OBJECTIVE: To describe the postconcussion recovery of postural control using approximate entropy (ApEn), a regularity statistic from nonlinear dynamics. DESIGN: Retrospective case series analysis. SETTING: Sports medicine research laboratory. PATIENTS OR OTHER PARTICIPANTS: Collegiate athletes from whom center-of-pressure and symptom data were collected at preseason, less than 48 hours after injury, and 48 to 96 hours after injury. MAIN OUTCOME MEASURE(S): Approximate entropy values reflecting the amount of randomness contained in center-of-pressure oscillations were calculated for anterior-posterior (AP) and medial-lateral (ML) time series. Equilibrium scores reflecting the amplitude of center-of-pressure AP oscillations were used to indicate postural stability. The number and severity of symptoms were described. RESULTS: Compared with the healthy preseason state, ApEn values for the AP and ML time series generally declined immediately after injury in both steady and unsteady injured athletes. At 48 to 96 hours after injury, ApEn values for the ML time series remained significantly depressed (mean difference compared with preseason = -0.268, standard error = 0.072), even among athletes whose initial postural instability had resolved. We found few significant relationships between changes in ApEn values and changes in symptoms before and after injury. CONCLUSIONS: The effects of cerebral concussion on postural control appear to persist for longer than 3 to 4 days, even among athletes with no signs of unsteadiness. Our results may reflect changes in neurophysiologic or mechanical constraints on postural control. Approximate entropy provides a theoretically distinct, valuable measurement alternative that may prove useful for reducing uncertainty in the return-to-play decision.