Nima Toosizadeh

Frailty is a geriatric syndrome that leads to impairment in interrelated physiological systems and progressive homeostatic dysregulation in physiological systems. The focus of the present systematic review was to study the association between the activity of the cardiac autonomic nervous system (ANS) and frailty. A systematic literature search was conducted in multiple databases: PubMed/MEDLINE, Embase, Cochrane Library, Web of Science, CINAHL, and ClinicalTrials.gov; the last search was performed in March 2015. Inclusion criteria were: (1) that the studied population was classified for frailty according to a standard definition, such as Fried's criteria; (2) that the study had a nonfrail control group, and (3) that heart rate (HR) and/or heart rate variability (HRV) were parameters of interest in the study. Of the 1,544 articles screened, 54 were selected for full-text review and 6 studies met the inclusion criteria. Assessment of HRV using different standard time domain, frequency domain, and nonlinear domain approaches confirmed the presence of an impaired cardiac ANS function in frail compared to nonfrail participants. Furthermore, HR changes while performing a clinical test (e.g., the seated step test or the lying-to-standing orthostatic test) were decreased in the frail group compared to the nonfrail group. The current systematic review provides evidence that the cardiac ANS is impaired in frail compared to nonfrail older adults, as indicated by a reduction in the complexity of HR dynamics, reduced HRV, and reduced HR changes in response to daily activities. Four out of 6 included articles recruited only female participants, and in the other 2 articles the effect of gender on impairment of cardiac ANS was insufficiently investigated. Therefore, further studies are required to study the association between cardiac ANS impairments and frailty in males. Furthermore, HRV was studied only during static postures such as sitting, or without considering the level of activity as a potential confounder. Accordingly, simultaneous measurement of both physiological (i.e., HRV) and kinematic (e.g., using wearable sensor technology) information may provide a better understanding of cardiac ANS impairments with frailty while controlling for activity. © 2015 S. Karger AG, Basel.

Objective motor performance measures, especially gait assessment, could improve evaluation of low back disorder surgeries. However, no study has compared the relative effectiveness of gait parameters for assessing motor performance in low back disorders after surgery. The purpose of the current review was to determine the sensitive gait parameters that address physical improvements in each specific spinal disorder after surgical intervention. Articles were searched with the following inclusion criteria: 1) population studied consisted of individuals with low back disorders requiring surgery; 2) low back disorder was measured objectively using gait assessment tests pre- and post-surgery. The quality of the selected studies was assessed using Delphi consensus, and meta-analysis was performed to compare pre- and post-surgical changes. Thirteen articles met inclusion criteria, which, almost exclusively, addressed two types of spinal disorders/interventions: 1) scoliosis/spinal fusion; and 2) stenosis/decompression. For patients with scoliosis, improvements in hip and shoulder motion (effect size=0.32-1.58), energy expenditure (effect size=0.59-1.18), and activity symmetry of upper-body muscles during gait were present after spinal fusion. For patients with spinal stenosis, increases in gait speed, stride length, cadence, symmetry, walking smoothness, and walking endurance (effect size=0.60-2.50), and decrease in gait variability (effect size=1.45) were observed after decompression surgery. For patients with scoliosis, gait improvements can be better assessed by measuring upper-body motion and EMG rather than the lower extremities. For patients with spinal stenosis, motor performance improvements can be captured by measuring walking spatio-temporal parameters, gait patterns, and walking endurance.

To objectively identify frailty using wireless sensors and an innovative upper extremity motion assessment routine that does not rely on gait. Validation study. Southwestern tertiary academic medical center, Tucson, Arizona. Convenience subsample of the Arizona Frailty Cohort, a community-dwelling older adults (≥65; n = 117; 50 nonfrail, 51 prefrail, 16 frail). Wireless sensors were attached to the upper arm and forearm with bands, and subjects performed repetitive elbow flexion for 20 seconds on each side. Information was extracted on objective slowness, weakness, exhaustion, and flexibility measures, and associations between parameters and Fried frailty categories were determined. Speed of elbow flexion (slowness) was 29% less in prefrail and 59% less in frail than in nonfrail controls (P < .001), power of movement (weakness) was 61% less in prefrail and 89% less frail (P < .001), and speed variation (exhaustion) was 35% more in prefrail and 272% more in frail (P < .001). Using elbow flexion parameters in regression models, sensitivity and specificity of 100% were achieved in predicting frailty and sensitivity of 87% and specificity of 95% in predicting prefrailty compared to Fried frailty category. The suggested innovative upper extremity frailty assessment method integrates low-cost sensors, and the physical assessment is easily performed in less than 1 minute. The uniqueness of the proposed technology is its applicability in older nonambulatory individuals, such as those in emergency settings. Further improvement is warrant to make it suitable for routine clinical applications.

Advances in wearable technology allow for the objective assessment of motor performance in both in-home and in-clinic environments and were used to explore motor impairments in Parkinson's disease (PD). The aims of this study were to: 1) assess differences between in-clinic and in-home gait speed, and sit-to-stand and stand-to-sit duration in PD patients (in comparison with healthy controls); and 2) determine the objective physical activity measures, including gait, postural balance, instrumented Timed-up-and-go (iTUG), and in-home spontaneous physical activity (SPA), with the highest correlation with subjective/semi-objective measures, including health survey, fall history (fallers vs. non-fallers), fear of falling, pain, Unified Parkinson's Disease Rating Scale, and PD stage (Hoehn and Yahr). Objective assessments of motor performance were made by measuring physical activities in the same sample of PD patients (n = 15, Age: 71.2±6.3 years) and age-matched healthy controls ...

As the population of older adults quickly increases, the incidence of frailty syndrome, a reduction in physiological reserve across multiple physiological systems, likewise increases. To date, impaired balance has been associated with frailty; however, the underlying frailty-related postural balance mechanisms remain unclear. The aim of the current study was to use open-loop (OL; postural muscles) and closed-loop (CL; postural muscles plus sensory feedback) mechanisms to explore differences in postural balance mechanisms between nonfrail (n = 44), prefrail (n = 59) and frail individuals (n = 19). One hundred and twenty-two older adults (age ≥65 years) without major mobility disorders were recruited, and frailty was measured using Fried's criteria. Each participant performed two 15-second trials of Romberg balance assessment, once with their eyes open and once with their eyes closed. Body-worn sensors were used to estimate center of gravity (COG) plots. Body-sway (traditional sta...

Motorized mobility scooters (MMS) have become the most acceptable powered assistive device for those with impaired mobility, who have sufficient upper body strength and dexterity, and postural stability. Although several benefits have been attributed to MMS usage, there are likewise risks of use, including injuries and even deaths. The aim of the current review was to summarize results from clinical studies regarding the enhancement of MMS driver safety with a primary focus on improving driving skills/performance using clinical approaches. We addressed three main objectives: (1) to identify and summarize any available evidence (strong, moderate, or weak evidence based on the quality of studies) regarding improved driving skills/performance following training/intervention; (2) to identify types of driving skills/performance that might be improved by training/intervention, and (3) to identify the use of technology in improving MMS performance or training procedure. Articles were searc...

ABSTRACT OBJECTIVE: Assessing effectiveness of a standardized electro-acupuncture (EA) regimen for improving balance and gait in patients with idiopathic Parkinson’s Disease (PD) using objective modalities employing innovative body-worn sensor technology.BACKGROUND: Balance and gait disturbances, predictors of falling risk and impaired quality of life, have emerged as major therapeutic concerns in PD. While acupuncture is increasingly used as a complementary PD therapy, objective measures of its effectiveness in improving clinically relevant ambulatory performance in PD are lacking.DESIGN/METHODS:Thirteen PD patients were randomly assigned to an intervention group (n=10) or a control group (n=3). All patients underwent either real or sham acupuncture for 3 weeks in once-weekly, 30-minute sessions. Outcomes were assessed in an off-medication state at baseline prior to and at the end of therapy. Measurements included balance (assessed by ratio of mediolateral center of mass sway to anteroposterior sway during eyes open, eyes closed, and eyes open dual-task), gait (assessed during single-task vs. dual-task habitual or fast walking), postural transitions (assessed by Timed Up and Go, TUG), quality of life (SF12) and UPDRS.RESULTS:Significant improvement occurred in the intervention group compared to baseline for balance, gait, TUG, SF12, UPDRS II on fall and UPDRS III. Overall balance improved by 31% (reduction in ML/AP sway); gait speed increased by 10%, and stride length increased by 5% among all participants in active group for all different conditions of testing. No improvement for any measurement was found in the control group compared to baseline. No between group difference was observed for baseline assessments and demographic information (P>0.11). After treatment, between groups comparison revealed that balance, gait speed and stride length during all conditions was significantly better in the intervention group compared to control group (p<0.05).CONCLUSIONS: EA is an effective therapy in improving certain aspects of balance and gait disorders in PD.

Experimental studies suggest that flexed working postures reduce passive support of the spine, which could represent a significant risk factor for the development of occupational low back disorders. Neuromuscular compensations to reduced passive stiffness include increases in baseline activity or reflexive activation of trunk muscles. Yet, alterations and recovery of the synergy between active and passive tissues following prolonged flexion in humans are currently unknown. Twelve healthy participants were exposed to all combinations of two trunk flexion durations (2 and 16 min) and three flexion angles (33, 66, and 100% of individual flexion-relaxation angle). Load relaxation was recorded throughout exposures, whereas trunk stiffness and reflexive behaviors of the lumbar extensor muscles were investigated during dynamic responses to sudden perturbations. The magnitude of load relaxation increased with increasing flexion angle. Trunk stiffness decreased and reflex gains increased following flexion exposures; for both outcomes, acute changes were larger following exposure to increasing flexion angle. Reflex gains remained elevated one hour after exposure to maximum flexion. Exposure to prolonged trunk flexion changed trunk stiffness and reflex behavior in patterns consistent with epidemiological evidence linking such exposure with the risk of occupational low back disorders. Observed increases in reflex gains, at least among healthy individuals, may be a compensation for decreases in passive trunk stiffness following acute exposure to flexed postures. It remains to be determined whether the neuromuscular system can similarly respond to accumulated disturbances in passive structures following exposure to repeated flexion tasks.

ABSTRACT Occupations involving frequent trunk flexion are associated with a higher incidence of low back pain. To investigate the effects of repeated static flexion on trunk behaviors, 12 participants completed six combinations of three static flexion durations (1, 2, and 4 min), and two flexion duty cycles (33% and 50%). Trunk mechanical and neuromuscular behaviors were obtained pre- and post-exposure and during recovery using sudden perturbations. A longer duration of static flexion and a higher duty cycle increased the magnitude of decrements in intrinsic stiffness. Increasing duty cycle caused larger decreases in reflexive muscle responses, and females had substantially larger decreases in reflexive responses following exposure. Patterns of recovery for intrinsic trunk stiffness and reflexive responses were consistent across conditions and genders, and none of these measures returned to pre-exposure values after 20 min of recovery. Reflexive responses may not provide a compensatory mechanism to offset decreases in intrinsic trunk stiffness following repetitive static trunk flexion. A prolonged recovery duration may lead to trunk instability and a higher risk of low back injury.

Poor balance control and increased fall risk have been reported in people with diabetic peripheral neuropathy (DPN). Traditional body sway measures are unable to describe underlying postural control mechanism. In the current study, we used stabilogram diffusion analysis to examine the mechanism under which balance is altered in DPN patients under local-control (postural muscle control) and central-control (postural control using sensory cueing). DPN patients and healthy age-matched adults over 55 years performed two 15-second Romberg balance trials. Center of gravity sway was measured using a motion tracker system based on wearable inertial sensors, and used to derive body sway and local/central control balance parameters. Eighteen DPN patients (age = 65.4±7.6 years; BMI = 29.3±5.3 kg/m2) and 18 age-matched healthy controls (age = 69.8±2.9; BMI = 27.0±4.1 kg/m2) with no major mobility disorder were recruited. The rate of sway within local-control was significantly higher in the DPN group by 49% (healthy local-controlslope = 1.23±1.06×10-2 cm2/sec, P<0.01), which suggests a compromised local-control balance behavior in DPN patients. Unlike local-control, the rate of sway within central-control was 60% smaller in the DPN group (healthy central-controlslope-Log = 0.39±0.23, P<0.02), which suggests an adaptation mechanism to reduce the overall body sway in DPN patients. Interestingly, significant negative correlations were observed between central-control rate of sway with neuropathy severity (rPearson = 0.65-085, P<0.05) and the history of diabetes (rPearson = 0.58-071, P<0.05). Results suggest that in the lack of sensory feedback cueing, DPN participants were highly unstable compared to controls. However, as soon as they perceived the magnitude of sway using sensory feedback, they chose a high rigid postural control strategy, probably due to high concerns for fall, which may increase the energy cost during extended period of standing; the adaptation mechanism using sensory feedback depends on the level of neuropathy and the history of diabetes.