Academy of Geriatric Physical Therapy Research Agenda: Rationale for the Development and the Intent for Use.

The rationale for the development and the intent for use of a research agenda for the Academy of Geriatric Physical Therapy is described. The reasons for the research agenda for geriatric physical therapy are (1) to have a broad representation of the research conducted by physical therapist(s) working with older adults, (2) to provide guidance and assistance to emerging investigators to aid the trajectory of a research career, and (3) as a document to engage potential funding agencies, foundations, and individuals in support of physical therapist-conducted research. The design was based on the Research Agenda for Physical Therapy (APTA document), formatted to be consistent with the World Health Organization International Classification of Functioning, Disability and Health, priority ratings for the research statements, and specific examples of research questions for each category of the Research Agenda. The Academy of Geriatric Physical Therapy Research Agenda generated to be a living document, with revisions to research questions and priority ratings expected in the future to enable the agenda to adapt to changes in science, practice, workforce, education, and health policy.

The Figure-of-8 Walk Test used to detect the loss of motor skill in walking among persons with Parkinson's disease.

BACKGROUND: The Figure-of-8 Walk Test (F8W) is a valid measure of walking skill in older adults with a mobility disability. Use of the F8W in assessing walking skill in persons with Parkinson's disease (PWP) is unknown. PURPOSE: We examined the validity of the F8W by associations with mobility, and cognitive and physical function, and determined the ability of the F8W to discriminate the motor skill of walking in PWP from that of older adults (OA). METHODS: Participants, PWP (n = 60) and OA (n = 34) performed the F8W, usual straight path walking, the Montreal Cognitive Assessment (MoCA), and the Late-Life Function and Disability Instrument (LLFDI). RESULTS: Among PWP, F8W time and steps related to: usual gait speed (r = -0.660, -0.650); stride time variability (r = 0.377, 0.438); cognition (r = -0.293, time only); and physical function (r = -0.532, - 0.619), all p < .05. Area under the curve (AUC) analyses demonstrated greater sensitivity and specificity of F8W performance (0.811, 0.790) compared to usual gait speed (0.729) to recognize the motor skill of walking in PWP from that of OA. CONCLUSION: The F8W is a valid indicator of the motor skill of walking in PWP. Use of the F8W may uncover walking difficulties not identified by usual gait speed.

Long-term Effects of Calcium ß-Hydroxy-ß-Methylbutyrate and Vitamin D3 Supplementation on Muscular Function in Older Adults With and Without Resistance Training: A Randomized, Double-blind, Controlled Study.

The primary aim of this study was to determine whether supplementation with calcium ß-hydroxy-ß-methylbutyrate (HMB) and vitamin D3 (D) would enhance muscle function and strength in older adults. Older adults over 60 years of age with insufficient circulating 25-hydroxy-vitamin D (25OH-D) levels were enrolled in a double-blinded controlled 12-month study. Study participants were randomly assigned to treatments consisting of: (a) Control + no exercise, (b) HMB+D + no exercise, (c) Control + exercise, and (d) HMB+D + exercise. The study evaluated 117 participants via multiple measurements over the 12 months that included body composition, strength, functionality, and questionnaires. HMB+D had a significant benefit on lean body mass within the nonexercise group at 6 months (0.44 ± 0.27 kg, HMB+D vs -0.33 ± 0.28 kg, control, p < .05). In nonexercisers, improvement in knee extension peak torque (60°/s) was significantly greater in HMB+D-supplemented participants than in the nonsupplemented group (p = .04) at 3 months, 10.9 ± 5.7 Nm and -5.2 ± 5.9 Nm, respectively. A composite functional index, integrating changes in handgrip, Get Up, and Get Up and Go measurements, was developed. HMB+D + no exercise resulted in significant increases in the functional index compared with those observed in the control + no exercise group at 3 (p = .03), 6 (p = .04), and 12 months (p = .04). Supplementation with HMB+D did not further improve the functional index within the exercising group. This study demonstrated the potential of HMB and vitamin D3 supplementation to enhance muscle strength and physical functionality in older adults, even in individuals not engaged in an exercise training program.

Does Instructor Experience Impact Balance and Health-Related Quality of Life in Healthy Older Adult Participants following a Tai Chi for Arthritis Program?

Tai chi improves balance in older adults; however, the level of instructor expertise on balance outcomes is not known. Older adults (mean age 72.6 ± 4.2 yrs.) were taught for 6 months by experienced (n = 15) or novice (n = 11) instructors. Both groups had large standardized response means (SRM) for the Four-Square-Step-Test. Only the experienced group had moderate to large SRMs (range 0.439-0.741) in all sway measures under challenge (standing with eyes closed on foam). Participants taught by experienced instructors had greater balance gains; the experience of instructors should be considered in future studies and community referrals.

Spatiotemporal variability underlying skill in curved-path walking.

BACKGROUND: Daily life walking frequently involves curved paths. While mean gait characteristics and orientation of the body during curved path walking have been described, little has been reported about spatiotemporal variability during curved path walking and its relation to the motor skill of walking in older adults. RESEARCH QUESTION: Among community-dwelling older adults, is greater spatiotemporal variability during curved path walking related to better curved path walking ability? METHODS: Community dwelling older adults (n = 34) completed the Figure-of-8 Walk Test (F8W, a measure of curved path walking ability) and usual straight path walking on an instrumented walkway. Standard deviations for step length, stride width and step time (step length variability, SLV, stride width variability, SWV, step time variability, STV) during both conditions were determined, along with time and number of steps to complete F8W. Associations were examined with Pearson r correlation coefficients, regressions determined contributions of variability during curved path walking to F8W performance, and AUC analyses were used to determine the ability of variability during curved path walking to distinguish better vs poorer F8W performance. RESULTS: F8W time and steps were negatively associated with both SLV (r's = -0.37, p < 0.05) and SWV (r's = -0.67 to -0.82, p < 0.001). Both SLV and SWV independently contributed to F8W performance (SLV ßs = -0.26 to -0.29, p < 0.03; SWV ßs = -0.74 to -0.76, p < 0.001). The AUC of the ROC curve for SLV was 0.716, and for SWV was 0.765. SIGNIFICANCE: Greater spatial variability, particularly SWV, was associated with better motor skill of curved path walking. It is important for clinicians to understand the variables that contribute to successful performance of complex walking tasks as these can be targets for rehabilitation. The findings suggest that practice of adjustment of stride width and step length during walking are important.

Age-Related Differences in Locomotor Strategies During Adaptive Walking.

Simultaneous control of lower limb stepping movements and trunk motion is important for skilled walking; adapting gait to environmental constraints requires frequent alternations in stepping and trunk motion. These alterations provide a window into the locomotor strategies adopted by the walker. The authors examined gait strategies in young and healthy older adults when manipulating step width. Anteroposterior (AP) and mediolateral (ML) smoothness (quantified by harmonic ratios) and stepping consistency (quantified by gait variability) were analyzed during narrow and wide walking while controlling cadence to preferred pace. Results indicated older adults preserved ML smoothness at the expense of AP smoothness, shortened their steps, and exhibited reduced stepping consistency. The authors conclude that older adults prioritized ML control over forward progression during adaptive walking challenges.

Extraction of stride events from gait accelerometry during treadmill walking.

OBJECTIVE: Evaluating stride events can be valuable for understanding the changes in walking due to aging and neurological diseases. However, creating the time series necessary for this analysis can be cumbersome. In particular, finding heel contact and toe-off events which define the gait cycles accurately are difficult. METHOD: We proposed a method to extract stride cycle events from tri-axial accelerometry signals. We validated our method via data collected from 14 healthy controls, 10 participants with Parkinson's disease and 11 participants with peripheral neuropathy. All participants walked at self-selected comfortable and reduced speeds on a computer-controlled treadmill. Gait accelerometry signals were captured via a tri-axial accelerometer positioned over the L3 segment of the lumbar spine. Motion capture data were also collected and served as the comparison method. RESULTS: Our analysis of the accelerometry data showed that the proposed methodology was able to accurately extract heel and toe contact events from both feet. We used t-tests, ANOVA and mixed models to summarize results and make comparisons. Mean gait cycle intervals were the same as those derived from motion capture and cycle-to-cycle variability measures were within 1.5%. Subject group differences could be identified similarly using measures with the two methods. CONCLUSIONS: A simple tri-axial acceleromter accompanied by a signal processing algorithm can be used to capture stride events. Clinical Impact: The proposed algorithm enables the assessment of stride events during treadmill walking, and is the first step towards the assessment of stride events using tri-axial accelerometers in real-life settings.

Understanding the effects of pre-processing on extracted signal features from gait accelerometry signals.

Gait accelerometry is an important approach for gait assessment. Previous contributions have adopted various pre-processing approaches for gait accelerometry signals, but none have thoroughly investigated the effects of such pre-processing operations on the obtained results. Therefore, this paper investigated the influence of pre-processing operations on signal features extracted from gait accelerometry signals. These signals were collected from 35 participants aged over 65years: 14 of them were healthy controls (HC), 10 had Parkinson׳s disease (PD) and 11 had peripheral neuropathy (PN). The participants walked on a treadmill at preferred speed. Signal features in time, frequency and time-frequency domains were computed for both raw and pre-processed signals. The pre-processing stage consisted of applying tilt correction and denoising operations to acquired signals. We first examined the effects of these operations separately, followed by the investigation of their joint effects. Several important observations were made based on the obtained results. First, the denoising operation alone had almost no effects in comparison to the trends observed in the raw data. Second, the tilt correction affected the reported results to a certain degree, which could lead to a better discrimination between groups. Third, the combination of the two pre-processing operations yielded similar trends as the tilt correction alone. These results indicated that while gait accelerometry is a valuable approach for the gait assessment, one has to carefully adopt any pre-processing steps as they alter the observed findings.

Improving motor control in walking: a randomized clinical trial in older adults with subclinical walking difficulty.

OBJECTIVE: To test the proposed mechanism of action of a task-specific motor learning intervention by examining its effect on measures of the motor control of gait. DESIGN: Single-blinded randomized clinical trial. SETTING: University research laboratory. PARTICIPANTS: Adults (N=40) aged ≥65 years with gait speed >1.0m/s and impaired motor skill (figure-of-8 walk time >8s). INTERVENTIONS: The 2 interventions included a task-oriented motor learning and a standard exercise program; both interventions included strength training. Both lasted 12 weeks, with twice-weekly, 1-hour, physical therapist-supervised sessions. MAIN OUTCOME MEASURES: Two measures of the motor control of gait, gait variability and smoothness of walking, were assessed pre- and postintervention by assessors masked to the treatment arm. RESULTS: Of 40 randomized subjects, 38 completed the trial (mean age ± SD, 77.1±6.0y). The motor learning group improved more than the standard group in double-support time variability (.13m/s vs .05m/s; adjusted difference [AD]=.006, P=.03). Smoothness of walking in the anteroposterior direction improved more in the motor learning than standard group for all conditions (usual: AD=.53, P=.05; narrow: AD=.56, P=.01; dual task: AD=.57, P=.04). Smoothness of walking in the vertical direction also improved more in the motor learning than standard group for the narrow-path (AD=.71, P=.01) and dual-task (AD=.89, P=.01) conditions. CONCLUSIONS: Among older adults with subclinical walking difficulty, there is initial evidence that task-oriented motor learning exercise results in gains in the motor control of walking, while standard exercise does not. Task-oriented motor learning exercise is a promising intervention for improving timing and coordination deficits related to mobility difficulties in older adults, and needs to be evaluated in a definitive larger trial.

A comprehensive assessment of gait accelerometry signals in time, frequency and time-frequency domains.

Gait accelerometry is a promising tool to assess human walking and reveal deteriorating gait characteristics in patients and can be a rich source of clinically relevant information about functional declines in older adults. Therefore, in this paper, we present a comprehensive set of signal features that may be used to extract clinically valuable information from gait accelerometry signals. To achieve our goal, we collected tri-axial gait accelerometry signals from 35 adults 65 years of age and older. Fourteen subjects were healthy controls, 10 participants were diagnosed with Parkinson's disease, and 11 participants were diagnosed with peripheral neuropathy. The data were collected while the participants walked on a treadmill at a preferred walking speed. Accelerometer signal features in time, frequency and time-frequency domains were extracted. The results of our analysis showed that some of the extracted features were able to differentiate between healthy and clinical populations. Signal features in all three domains were able to emphasize variability among different groups, and also revealed valuable information about variability of the signals between anterior-posterior, mediolateral, and vertical directions within subjects. The current results imply that the proposed signal features can be valuable tools for the analysis of gait accelerometry data and should be utilized in future studies.

Walking smoothness is associated with self-reported function after accounting for gait speed.

BACKGROUND: Gait speed has shown to be an indicator of functional status in older adults; however, there may be aspects of physical function not represented by speed but by the quality of movement. The purpose of this study was to determine the relations between walking smoothness, an indicator of the quality of movement based on trunk accelerations, and physical function. METHODS: Thirty older adults (mean age, 77.7±5.1 years) participated. Usual gait speed was measured using an instrumented walkway. Walking smoothness was quantified by harmonic ratios derived from anteroposterior, vertical, and mediolateral trunk accelerations recorded during overground walking. Self-reported physical function was recorded using the function subscales of the Late-Life Function and Disability Instrument. RESULTS: Anteroposterior smoothness was positively associated with all function components of the Late-Life Function and Disability Instrument, whereas mediolateral smoothness exhibited negative associations. Adjusting for gait speed, anteroposterior smoothness remained associated with the overall and lower extremity function subscales, whereas mediolateral smoothness remained associated with only the advanced lower extremity subscale. CONCLUSION: These findings indicate that walking smoothness, particularly the smoothness of forward progression, represents aspects of the motor control of walking important for physical function not represented by gait speed alone.

The dose-response relationship of balance training in physically active older adults.

A 6-wk group balance-training program was conducted with physically active older adults (based on American College of Sports Medicine requirements) to investigate the effect of dose-related static and dynamic balance-specific training. All participants, age 60-87 yr, continued their regular exercise program while adding balance training in 1 of 3 doses: three 20-min sessions/wk (n = 20), one 20-min session/wk (n = 21), or no balance training (n = 19). Static balance (single-leg-stance, tandem), dynamic balance (alternate stepping, limits of stability), and balance confidence (ABC) were assessed pre- and posttraining. Significant interactions were observed for time in single-leg stance, excursion in limits of stability, and balance confidence, with the greatest increase observed in the group that completed 3 training sessions/wk. The results demonstrate a dose-response relationship indicating that those who are already physically active can improve balance performance with the addition of balance-specific training.

Contributions of cognitive function to straight- and curved-path walking in older adults.

OBJECTIVE: To determine whether the cognitive function contribution to straight- and curved-path walking differs for older adults. DESIGN: Cross-sectional observational study. SETTING: Ambulatory clinical research training center. PARTICIPANTS: People (N=106) aged 65 to 92 years, able to walk household distances independently with or without an assistive device, and who scored 24 or greater on the Mini-Mental State Examination. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Cognitive function was assessed using the Digit Symbol Substitution Test (DSST) as a measure of psychomotor speed, and Trail Making Test Parts A and B (TMT-A and TMT-B) and the Trail Making Test difference score (TMT-B-A) as executive function measures of complex visual scanning and set shifting. Gait speed recorded over an instrumented walkway was used as the measure of straight-path walking. Curved-path walking was assessed using the Figure-of-8 Walk Test (F8W) and recorded as the total time and number of steps for completion. RESULTS: Both DSST and TMT-A independently contributed to usual gait speed (P<.001). TMT-A performance contributed to F8W time (P<.001). Neither TMT-B nor TMT-B-A contributed to usual gait speed or time to complete the F8W. For the number of steps taken to complete the F8W, TMT-A, TMT-B, and TMT-B-A (all P<.001) were independent contributors, while DSST performance was not. CONCLUSIONS: Curved-path walking, as measured by the F8W, involves different cognitive processes compared with straight-path walking. Cognitive flexibility and set-shifting processes uniquely contributed to how individuals navigated curved paths. The measure of curved-path walking provides different and meaningful information about daily life walking ability than usual gait speed alone.

Successful aging as a continuum of functional independence: lessons from physical disability models of aging.

Successful aging is a multidimensional construct that could be viewed as a continuum of achievement. Based on the disability model proposed by the WHO International Classification of Functioning, Disability and Health, successful aging includes not only the presence or absence of disease, but also aspects of mobility and social participation. Here we review definitions of successful aging and discuss relevance of the disability model in the evaluation of successful aging and frailty. In particular, we summarize evidences that highlight the importance of measures of mobility (ability to walk and perform activities of daily living), and social participation in identifying and locating older adults across the range of the successful aging continuum. Lastly, we discuss the role of inflammation in age-related decline and in frailty. Future research directions are proposed, including identifying causal pathways among inflammatory markers, disability, and frailty. A better understanding of immunological functioning in late life may help unlock novel ways to promote successful aging.

Effects of extensive practice on bradykinesia in Parkinson's disease: improvement, retention and transfer.

We investigated the effects of extensive practice of rapid aiming on bradykinesia and, more specifically, generation of peak velocity, in discrete rapid aiming and in transfer to reach-to-grasp. Twenty-one participants (seven young adults, seven older adults, and seven adults with mild to moderate Parkinson's disease (PD) while on medication) engaged in eight practice periods per week for three weeks (> 700 trials), with changes in performance measured weekly. Retention was measured weekly for three weeks postpractice. Movement time decreased with one week of practice, primarily due to a decrease in time-to-peak velocity. With practice and after retention, the PD group generated peak velocity as consistently as both neurologically healthy groups, but remained more variable in time-to-peak velocity. Transfer was observed in the neurologically healthy groups, but not in the PD group. We concluded that short-term practice (one week in our paradigm) is sufficient for decreasing movement time, but more extensive practice is needed to improve consistency of rapid aiming performance for people with mild to moderate PD.

Use of harmonic ratios to examine the effect of cueing strategies on gait stability in persons with Parkinson's disease.

OBJECTIVE: To determine if gait stability, as measured by harmonic ratios (HRs) derived from trunk accelerations, is improved during 3 amplitude-based cueing strategies (visual cues, lines on the floor 20% longer than preferred step length; verbal cues, experimenter saying "big step" every third; cognitive cues, participants think "big step") in people with Parkinson's disease. DESIGN: Gait analysis with a triaxial accelerometer. SETTING: University research laboratory. PARTICIPANTS: A volunteer sample of persons with Parkinson's disease (N=7) (Hoehn and Yahr stages 2-3). INTERVENTIONS: Not applicable MAIN OUTCOME MEASURES: Gait stability was quantified by anterior-posterior (AP), vertical, and mediolateral (ML) HRs; higher ratios indicated improved gait stability. Spatiotemporal parameters assessed were walking speed, stride length, cadence, and the coefficient of variation for stride time. RESULTS: Of the amplitude-based cues, verbal and cognitive resulted in the largest improvements in the AP HR (P=.018) with a trend in the vertical HR as well as the largest improvements in both stride length and velocity. None of the cues positively affected stability in the ML direction. Descriptively, all participants increased speed and stride length, but only those in Hoehn and Yahr stage 2 (not Hoehn and Yahr stage 3) showed improvements in HRs. CONCLUSIONS: Cueing for "big steps" is effective for improving gait stability in the AP direction with modest improvements in the vertical direction, but it is not effective in the ML direction. These data support the use of trunk acceleration measures in assessing the efficacy of common therapeutic interventions.

Walking stability using harmonic ratios in Parkinson's disease.

Kinematic changes in Parkinson's disease (PD) gait are well documented; however, upper body dynamics are less understood. Harmonic ratios (HRs) measure the rhythm of trunk accelerations and can be examined in the vertical, anterior-posterior, and mediolateral planes, providing an indication of global walking stability (lower HR indicates poorer stability). We examined differences in HRs between persons with PD and healthy older adults and relationships between HRs and stride parameters. Eleven people with PD and 11 older adults walked over ground at their preferred pace. A triaxial accelerometer measured trunk accelerations. HRs and spatiotemporal parameters were calculated and standardized to remove the influence of gait velocity. The PD group exhibited lower HRs in all three planes, with the most pronounced differences in the mediolateral and anterior-posterior planes. Greater stride time variability was most closely associated with a lower anterior-posterior HR in PD and the presence of disease with the mediolateral HR. By demonstrating decreased walking stability in medial-lateral and anterior-posterior planes, we conclude that HRs offer unique information beyond that of typical stride parameters, and stride time variability is most closely associated with these direct measures of global walking stability.

Exercise, fitness, and neurocognitive function in older adults: the "selective improvement" and "cardiovascular fitness" hypotheses.

BACKGROUND: Although basic research has uncovered biological mechanisms by which exercise could maintain and enhance adult brain health, experimental human studies with older adults have produced equivocal results. PURPOSE: This randomized clinical trial aimed to investigate the hypotheses that (a) the effects of exercise training on the performance of neurocognitive tasks in older adults is selective, influencing mainly tasks with a substantial executive control component and (b) performance in neurocognitive tasks is related to cardiorespiratory fitness. METHODS: Fifty-seven older adults (65-79 years) participated in aerobic or strength-and-flexibility exercise training for 10 months. Neurocognitive tasks were selected to reflect a range from little (e.g., simple reaction time) to substantial (i.e., Stroop Word-Color conflict) executive control. RESULTS: Performance in tasks requiring little executive control was unaffected by participating in aerobic exercise. Improvements in Stroop Word-Color task performance were found only for the aerobic exercise group. Changes in aerobic fitness were unrelated to changes in neurocognitive function. CONCLUSIONS: Aerobic exercise in older adults can have a beneficial effect on the performance of speeded tasks that rely heavily on executive control. Improvements in aerobic fitness do not appear to be a prerequisite for this beneficial effect.

Learning and retention of movement sequences in Parkinson's disease.

The purpose of this study was to examine motor learning and retention given extensive practice in two fundamentally different movement sequences. One sequence was a memory-driven task (performing a series of whole body positions from memory) and the other a context-driven task (buttoning). Practice took place over 3 weeks, with performance measured weekly; retention was measured weekly for 3 weeks after practice. There were 7 people with Parkinson's disease (PD) and 7 age-matched neurologically healthy people who participated in this study. Both groups improved performance on both tasks with practice, with the majority of the change for the PD group occurring between 1 and 2 weeks of practice. Although those with PD did not necessarily perform as well as age-matched controls, they learned both sequences in a manner similar to age-matched controls, and exhibited retention across the 3-week retention interval. If people with PD are given sufficient practice they can learn and retain both memory-based and context-driven movement sequences as well as age-matched controls. The results provide support for maintaining physical activity and for intervention through movement therapy.