Validity and Reliability of Two-Dimensional Motion Analysis for Quantifying Postural Deficits in Adults With and Without Neurological Impairment.

Frequently, clinical balance outcome measures are limited by floor or ceiling effects and provide insufficient resolution to determine subtle deficits. Detailed assessment of postural control obtained through posturography may be cost-prohibitive or logistically infeasible in some clinical settings. Two-dimensional (2D) motion analysis may provide a clinically feasible means of obtaining detailed quantification of balance deficits. Forty-five participants aged 18-80 years, with and without Parkinson disease, performed the Push and Release (PR) test, sit-to-stand (STS), and timed single leg stance (SLS). Performance was captured simultaneously using a three-dimensional (3D) (10-camera laboratory-based 3D motion capture system and 3D motion analysis software) and 2D (two commercially available video cameras and 2D motion analysis software) system. Agreement was excellent between 2D and 3D systems for all outcomes of the PR and SLS (intraclass correlation coefficients [ICC2,1 ] 0.96-0.99, 95% CIs 0.92-0.98 to 0.99-1.0), and ranged from fair to excellent for STS outcomes (ICC2,1 0.59-0.93, 95% CIs 0.36-0.75 to 0.87-0.96). Test-retest reliability (ICC3,1 0.89-1.0, 95% CIs 0.76-0.96 to 1.0-1.0) and inter-rater reliability (ICC2,1 0.77-1.0, 95% CIs 0.61-0.87 to 1.0-1.0) of the 2D obtained outcomes were excellent. A technology package of commonly available video cameras and 2D motion analysis software was a valid and reliable method for quantifying outcomes of postural control tasks in people with a range of balance abilities. Two-dimensional analysis can be used in clinical practice to provide balance assessments as a cost-effective alternative to 3D motion capture. Anat Rec, 299:1165-1173, 2016. © 2016 Wiley Periodicals, Inc.

Intramuscular fat and inflammation differ in older adults: the impact of frailty and inactivity.

OBJECTIVES: Intramuscular adipose tissue (IMAT) is recognized as a negative predictor of both muscle and mobility function in older adults, however the mechanism by which IMAT may negatively influence muscle and mobility function is currently unknown. The release of pro-inflammatory cytokines from IMAT provides a potential reason for these negative associations. To explore this hypothesis we compared IMAT and muscular inflammation in age-and BMI-matched older non-obese frail and non-frail adults. We also sought to examine the relationship between IMAT and inflammation, and muscle and mobility function in this group of older adults. DESIGN: A case-control sampling was used for this study. Age-and BMI-matched non-obese frail and non-frail individuals (<65 years) were recruited. MEASUREMENTS: MRI was used to quantify thigh IMAT and lean tissue. Unilateral muscle biopsies were used to quantify muscular inflammation as represented by interleukin-6 (IL-6) and tumor-necrosis factor alpha (TNF-α). Muscle and mobility function was also measured using a maximal voluntary isometric contraction, six-minute walk, and self-selected gait speed. PARTICIPANTS: 26 older (80.7 +/- 5.4 years) individuals (8 frail and 18 non-frail) were enrolled. RESULTS: The frail-group had increased IMAT (p<0.01) and decreased lean tissue (p<0.01), and elevated IL-6 muscle mRNA (p=0.02) and IL-6 protein content (p=0.02) compared to the non-frail group. IMAT was significantly associated with IL-6 mRNA (r=0.43, p=.04) and protein expression within the muscle (r=0.41, p= 0.045). IL-6 mRNA was significantly associated with six-minute walk (r=-0.63, p<0.01), and gait speed (r=-0.60, p <0.01) and IL-6 protein was significantly associated with muscle force (r=-0.54, p=0.01), six-minute walk (r=-0.66, p<0.01), and gait speed (r=-0.76, p<0.01). No significant relationships were found for any variables with TNF-a. CONCLUSION: Non-obese, older, frail individuals have increased IMAT and muscular inflammation when compared to their non-frail, age- and BMI-matched peers. A significant relationship exists between IMAT and muscle IL-6 expression as well as between IL-6 and muscle and mobility function of these older adults. This IMAT-inflammatory pathway provides a potential link between IMATs and decreased muscle and mobility function.

Improved Dynamic Postural Task Performance without Improvements in Postural Responses: The Blessing and the Curse of Dopamine Replacement.

Introduction. Dopamine-replacement medications may improve mobility while not improving responses to postural challenges and could therefore increase fall risk. The purpose of this study was to measure reactive postural responses and gait-related mobility of patients with PD during ON and OFF medication conditions. Methods. Reactive postural responses to the Pull Test and performance of the Functional Gait Assessment (FGA) were recorded from 15 persons with PD during ON and OFF medication conditions. Results. Persons with PD demonstrated no significant difference in the reactive postural responses between medication conditions but demonstrated significantly better performance on the FGA when ON medications compared to OFF. Discussion/Conclusion. Dopamine-replacement medications alone may improve gait-related mobility without improvements in reactive postural responses and therefore could result in iatrogenic increases in fall risk. Rehabilitation providers should be aware of the side effects and limitations of medication treatment and implement interventions to improve postural responses.

Which measures of physical function and motor impairment best predict quality of life in Parkinson's disease?

INTRODUCTION: Our objective was to compare the relative value of elements of the motor system in predicting the physical mobility domain of health related quality of life in patients with Parkinson's disease in order to specify targets for intervention. METHODS: In this cross-sectional study, the Parkinson's disease questionnaire-39 was administered to 263 subjects with Parkinson's disease to assess health related quality of life. Demographics, motor impairments and physical function were assessed using the Unified Parkinson disease rating scale, 10-m walk test, 6-min walk test, Freezing of gait questionnaire, Timed up & go, functional gait assessment, Berg balance test, functional reach and 9-hole peg test. RESULTS: The results revealed that demographic factors accounted for 19.7% of the variance in Parkinson disease questionnaire-39 mobility score. When motor impairments were added to the model, the bradykinesia composite score contributed a significant portion of the variance (R(2) change = 0.12, p < 0.001). The tremor and rigidity composite scores did not contribute significantly. The Freezing of gait questionnaire was the strongest predictor (R(2) change = 0.23, p < 0.001) of the physical function tests followed by Functional gait assessment (R(2) change = 0.06, p < 0.001) and 6-min walk test (R(2) change = 0.01, p = 0.01). Collectively, 61% of the variance in Parkinson disease questionnaire-39 mobility score and 41.5% of the Parkinson disease questionnaire-39(total) score was accounted for. DISCUSSION: These results suggest greater value of physical function tests, and not tests of motor impairments, in predicting health related quality of life.

Testing balance and fall risk in persons with Parkinson disease, an argument for ecologically valid testing.

INTRODUCTION: Despite clear deficits in postural control, most clinical examination tools lack accuracy in identifying persons with Parkinson disease (PD) who have fallen or are at risk for falls. We assert that this is in part due to the lack of ecological validity of the testing. METHODS: To test this assertion, we examined the responsiveness and predictive validity of the Functional Gait Assessment (FGA), the Pull test, and the Timed up and Go (TUG) during clinically defined ON and OFF medication states. To address responsiveness, ON/OFF medication performance was compared. To address predictive validity, areas under the curve (AUC) of receiver operating characteristic (ROC) curves were compared. Comparisons were made using separate non-parametric tests. RESULTS: Thirty-six persons (24 male, 12 female) with PD (22 fallers, 14 non-fallers) participated. Only the FGA was able to detect differences between fallers and non-fallers for both ON/OFF medication testing. The predictive validity of the FGA and the TUG for fall identification was higher during OFF medication compared to ON medication testing. The predictive validity of the FGA was higher than the TUG and the Pull test during ON and OFF medication testing. DISCUSSION: In order to most accurately identify fallers, clinicians should test persons with PD in ecologically relevant conditions and tasks. In this study, interpretation of the OFF medication performance and use of the FGA provided more accurate prediction of those who would fall.

Skeletal muscle fat infiltration: impact of age, inactivity, and exercise.

Fat infiltration within the fascial envelope of the thigh or intermuscular adispose tissue (IMAT), has been shown to be associated with both adverse metabolic and mobility impairments in older individuals. More recent findings suggest these fat deposits may be associated with increasing age and inactivity; and perhaps exercise may be able to counter or mitigate this increase in IMAT. This brief report summarizes the literature with respect to IMAT and its relationship to increasing age, physical activity levels, muscle strength, mobility and metabolism in the elderly. Further, we present preliminary data suggesting that IMAT is associated with increasing age in individuals across disease states (r=0.47, p < 0.05), and that resistance exercise can decrease IMAT in older individuals with a variety of co-morbid conditions.