Susan W. Hunter

Neuromuscular contributions to the age-related reduction in muscle power: Mechanisms and potential role of high velocity power training

Although much of the literature on neuromuscular changes with aging has focused on loss of muscle mass and isometric strength, deficits in muscle power are more pronounced with aging and may be a more sensitive measure of neuromuscular degeneration. This review aims to identify the adaptations to the neuromuscular system with aging, with specific emphasis on changes that result in decreased muscle power. We discuss how these changes in neuromuscular performance can affect mobility, and ultimately contribute to an increased risk for falls in older adults. Finally, we evaluate the literature regarding high-velocity muscle power training (PT), and its potential advantages over conventional strength training for improving functional performance and mitigating fall risk in older adults.

Individualized home-based exercise programs for older people to reduce falls and improve physical performance: A systematic review and meta-analysis

There is considerable diversity in the types of exercise programs investigated to reduce falls in older people. The purpose of this paper was to review the effectiveness of individualized (tailored) home-based exercise programs in reducing falls and improving physical performance among older people living in the community. A systematic review and meta-analysis was conducted of randomized or quasi-randomized trials that utilized an individualized home-based exercise program with at least one falls outcome measure reported. Single intervention exercise studies, and multifactorial interventions where results for an exercise intervention were reported independently were included. Two researchers independently rated the quality of each included study. Of 16,871 papers identified from six databases, 12 met all inclusion criteria (11 randomized trials and a pragmatic trial). Study quality overall was high. Sample sizes ranged from 40 to 981, participants had an average age 80.1 years, and although the majority of studies targeted the general older population, several studies included clinical groups as their target (Parkinsons disease, Alzheimers disease, and hip fracture). The meta-analysis results for the five studies reporting number of fallers found no significant effect of the intervention (RR [95% CI]=0.93 [0.72-1.21]), although when a sensitivity analysis was performed with one study of participants recently discharged from hospital removed, this result was significant (RR [95% CI] = 0.84 [0.72-0.99]). The meta-analysis also found that intervention led to significant improvements in physical activity, balance, mobility and muscle strength. There were no significant differences for measures of injurious falls or fractures.

Risk factors for falls in people with a lower limb amputation: a systematic review

To review the evidence connecting risk factors to falls in adults with a lower limb amputation (LLA) across the continuum of care settings.

Association Between Montreal Cognitive Assessment Scores and Measures of Functional Mobility in Lower Extremity Amputees After Inpatient Rehabilitation

OBJECTIVE To determine whether scores on a cognitive measure are associated with walking endurance and functional mobility of individuals with transfemoral or transtibial amputations at discharge from inpatient prosthetic rehabilitation. DESIGN Retrospective cohort study. SETTING Rehabilitation hospital. PARTICIPANTS Consecutive admissions (N=176; mean age ± SD, 64.27±13.23y) with transfemoral or transtibial amputation that had data at admission and discharge from an inpatient prosthetic rehabilitation program. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Cognitive status was assessed using the Montreal Cognitive Assessment (MoCA). The L Test and the 2-minute walk test (2MWT) were used to estimate functional mobility and walking endurance. RESULTS The mean ± SD MoCA score was 24.05±4.09 (range, 6-30), and 56.3% of patients had scores <26. MoCA scores had a small positive correlation with the 2MWT (r=.29, P<.01), and a small negative correlation to the L Test (r=-.24, P<.01). In multivariable linear regression, compared with people with the highest MoCA score quartile, there was no difference on the 2MWT, but people in the lowest 2 quartiles took longer to complete the L Test. CONCLUSIONS Cognitive impairment was very prevalent. The association between MoCA and functional mobility was statistically significant. These results highlight the potential for differences on complex motor tasks for individuals with cognitive impairment but does not indicate a need to exclude them from rehabilitation on the basis of cognitive impairment alone.

A randomised trial comparing spatio-temporal gait parameters after total hip arthroplasty between the direct anterior and direct lateral surgical approaches

Introduction: Total hip arthroplasty (THA) is a successful procedure for relieving symptoms of severe osteoarthritis. Surgical approach is a key factor in early recovery and although controversial, little has been written about the direct anterior (DA) approach using objective early measures. Methods: 78 participants were prospectively enrolled to undergo a THA through either a DA or direct lateral (DL) surgical approach. Outcome measures were collected preoperatively and at discharge from the hospital, and 2-, 6- and 12-weeks. Outcome measures included the GAITRite® system to measure gait velocity, stride length, single-limb support and single-limb support symmetry. At each time point participants also completed the Timed Up and Go (TUG), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), 12-Item Short-Form Survey (SF-12), Harris Hip Score, and pain visual analog scale (VAS). Results: We found statistically significant differences in gait velocity at discharge, 2-weeks and 6-weeks in favour of the DA group (all p < 0.01). We also found significant differences in favour of the DA group for single-limb support symmetry at 6-weeks (p < 0.01) and 12-weeks (p < 0.01). The time to complete the TUG test was also significantly shorter in the DA group at 2-weeks (p < 0.01) and 6-weeks (p < 0.01) compared to the DL group. However, there were no statistically significant differences in any of the patient-reported outcomes. Conclusion: The DA surgical approach was found to offer significant early advantages in function compared to the DL group, with no differences in quality of life or pain.

Comparing the Effects of Dual-Task Gait Testing in New and Established Ambulators With Lower Extremity Amputations

Gait is a complex process that involves coordinating motor and sensory systems through higher‐order cognitive processes. Walking with a prosthesis after lower extremity amputation challenges these processes. However, the factors that influence the cognitive‐motor interaction in gait among lower extremity amputees has not been evaluated. To assess the interaction of cognition and mobility, individuals must be evaluated using the dual‐task paradigm.

Frailty Screening and Case-Finding for Complex Chronic Conditions in Older Adults in Primary Care

With the aging population, escalating demand for seniors’ care and limited specialist resources, new care delivery models are needed to improve capacity for primary health care for older adults. This paper describes the “C5-75” (Case-finding for Complex Chronic Conditions in Seniors 75+) program, an innovative care model aimed at identifying frailty and commonly associated geriatric conditions among older adults within a Canadian family practice setting and targeting interventions for identified conditions using a feasible, systematic, evidence-informed multi-disciplinary approach. We screen annually for frailty using gait speed and handgrip strength, screen for previously undiagnosed comorbid conditions, and offer frail older adults multi-faceted interventions that identify and address unrecognized medical and psychosocial needs. To date, we have assessed 965 older adults through this program; 14% were identified as frail based on gait speed alone, and 5% identified as frail based on gait speed with grip strength. The C5-75 program aims to re-conceptualize care from reactive interventions post-diagnosis for single disease states to a more proactive approach aimed at identifying older adults who are at highest risk of poor health outcomes, case-finding for unrecognized co-existing conditions, and targeting interventions to maintain health and well-being and potentially reduce vulnerability and health destabilization.

The effect of walking path configuration on gait in adults with Alzheimer’s dementia

BACKGROUND Walking is a cognition intensive activity and impaired walking is associated with an increased fall risk in people with Alzheimers dementia (AD). Walking in a curved path configuration increases complexity of the task, reflects real-life environments and situations when falls occur. The effect of walking path task complexity has not been evaluated in people with AD. RESEARCH QUESTION The purpose was 1) to assess the utility of a curved path walking task to detect differences in gait performance between people with AD and healthy controls and 2) to assess the relationship of cognitive function to gait performance on straight path and curved path walking. METHODS Participants with AD (n = 14, mean age ± SD = 73.08 ± 9.22) and age and sex matched controls (n = 14, mean age = 72.86 ± 9.53) were recruited. Time to complete a 6-meter straight path and a curved path (Figure of 8 Test) walking task was recorded. Steps taken, accuracy and qualitative measures of smoothness were rated for curved-path walking. Measures of global cognition (MMSE, MoCA) and executive function (Trail making A and B, Digit Span forwards and backwards) were assessed. RESULTS Gait was significantly slower in people with AD for both the straight-path (AD = 6.05 ± 1.26 s, Control = 5.09 ± 0.76 s, p = 0.02) and curved-path walking (AD = 11.25 ± 4.87 s, Control = 8.28 ± 2.44 s, p =  0.05). In addition, smoothness scores were significantly lower for people with AD (AD = 1.93±1.26; Control = 3.00±0.00, p = 0.004). SIGNIFICANCE Walking in a curved path resulted in a significant deterioration in gait quality in the people with AD. Executive function was related only to curved path walking, in which lower executive function scores were associated with longer time to walk.

Dual-task Related Gait Changes in Individuals with Trans-Tibial Lower Extremity Amputation

BACKGROUND The improvement of gait and mobility are major rehabilitation goals following lower extremity amputations. However, when living in the community many daily activities require the multitasking of motor and cognitive tasks. The dual-task paradigm can be used to evaluate the concurrent performance of mobility and cognitive tasks. RESEARCH QUESTION The purpose of this study was to evaluate the effects of dual-task gait testing in older adults with trans-tibial amputations. METHODS Twenty-four people (15 men, mean age ± SD, 62.72 ± 8.59) with trans-tibial amputation walked on an electronic walkway at i) self-selected comfortable pace and ii) self-selected comfortable pace while counting backwards by threes from a number randomly selected between 100 and 150. Cognitive performance, in the form of corrected response rate, was also evaluated as a single-task. RESULTS The dual-task testing produced poorer performance in velocity (single-task = 58.15 ± 23.16 cm/s, dual-task = 50.92 ± 21.16 cm/s, p = 0.008), cadence (single-task = 76.65 ± 15.84 steps/min, dual-task = 67.85 ± 15.76 steps/min, p = 0.002) and stride time (single-task = 1094 ± 458.28 ms, dual-task = 1241.44 ± 513.73 ms, p = 0.005). Step length, stance time and single limb support time symmetry were also affected, such that less time was spent on the amputated limb during the dual-task testing. SIGNIFICANCE Dual-task testing demonstrated interference resulting in a poor performance in both gait and cognitive performance in trans-tibial amputees. Further research is suggested to evaluate the change in cognition-mobility effects over time and the relationship of this value to future adverse events such as falls and successful outcomes such as community ambulation and reintegration.

Determining Reliability of a Dual-Task Functional Mobility Protocol for Individuals With Lower Extremity Amputation

OBJECTIVE To determine the relative and absolute reliability of a dual-task functional mobility assessment. DESIGN Cross-sectional study. SETTING Academic rehabilitation hospital. PARTICIPANTS Individuals (N=60) with lower extremity amputation attending an outpatient amputee clinic (mean age, 58.21±12.59y; 18, 80% male) who were stratified into 3 groups: (1) transtibial amputation of vascular etiology (n=20); (2) transtibial amputation of nonvascular etiology (n=20); and (3) transfemoral or bilateral amputation of any etiology (n=20). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Time to complete the L Test measured functional mobility under single- and dual-task conditions. The addition of a cognitive task (serial subtractions by 3s) created dual-task conditions. Single-task performance on the cognitive task was also reported. Intraclass correlation coefficients (ICCs) measured relative reliability; SEM and minimal detectable change with a 95% confidence interval (MDC95) measured absolute reliability. Bland-Altman plots measured agreement between assessments. RESULTS Relative reliability results were excellent for all 3 groups. Values for the dual-task L Test for those with transtibial amputation of vascular etiology (n=20; mean age, 60.36±7.84y; 19, 90% men) were ICC=.98 (95% confidence interval [CI], .94-.99), SEM=1.36 seconds, and MDC95=3.76 seconds; for those with transtibial amputation of nonvascular etiology (n=20; mean age, 55.85±14.08y; 17, 85% men), values were ICC=.93 (95% CI, .80-.98), SEM=1.34 seconds, and MDC95=3.71 seconds; and for those with transfemoral or bilateral amputation (n=20; mean age, 58.21±14.88y; 13, 65% men), values were ICC=.998 (95% CI, .996-.999), SEM=1.03 seconds, and MDC95=2.85 seconds. Bland-Altman plots indicated that assessments did not vary systematically for each group. CONCLUSIONS This dual-task assessment protocol achieved approved levels of relative reliability values for the 3 groups tested. This protocol may be used clinically or in research settings to assess the interaction between cognition and functional mobility in the population with lower extremity amputation.