Isometric and isokinetic back and arm lifting strengths: Device and measurement

This study was conducted to measure isometric (static) and isokinetic (dynamic) back and arm lifting strengths at 20, 60 and 100 cm s-1 of young adults. Ten male and ten female volunteers without a history of back pain participated. The isokinetic lifting task was achieved by designing and fabricating a servo controlled motorized dynamic strength tester (DST). A regression analysis and analysis of variance was carried out on the strength data. The peak static strength values were significantly greater from the peak dynamic strength values. The peak dynamic strength was inversely related to the speed of motion. There were significant differences between the dynamic strengths at different stages of lift.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27450/1/0000490.pd

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, analysis of variance (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 similarly identified using measures with the two methods. Conclusions: a simple tri-axial accelerometer 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 toward the assessment of stride events using tri-axial accelerometers in real-life settings

Simulator sickness when performing gaze shifts within a wide field of view optic flow environment: preliminary evidence for using virtual reality in vestibular rehabilitation

BACKGROUND: Wide field of view virtual environments offer some unique features that may be beneficial for use in vestibular rehabilitation. For one, optic flow information extracted from the periphery may be critical for recalibrating the sensory processes used by people with vestibular disorders. However, wide FOV devices also have been found to result in greater simulator sickness. Before a wide FOV device can be used in a clinical setting, its safety must be demonstrated. METHODS: Symptoms of simulator sickness were recorded by 9 healthy adult subjects after they performed gaze shifting tasks to locate targets superimposed on an optic flow background. Subjects performed 8 trials of gaze shifting on each of the six separate visits. RESULTS: The incidence of symptoms of simulator sickness while subjects performed gaze shifts in an optic flow environment was lower than the average reported incidence for flight simulators. The incidence was greater during the first visit compared with subsequent visits. Furthermore, the incidence showed an increasing trend over the 8 trials. CONCLUSION: The performance of head unrestrained gaze shifts in a wide FOV optic flow environment is tolerated well by healthy subjects. This finding provides rationale for testing these environments in people with vestibular disorders, and supports the concept of using wide FOV virtual reality for vestibular rehabilitation

High-pass filtering to remove electrocardiographic interference from torso EMG recordings

SummaryRemoval of electrocardiographic (ECG) contamination of electromyographic (EMG) signals from torso muscles is often attempted by high-pass filtering. This study investigated the effects of the cut-off frequency used in this high-pass filtering technique on the resulting EMG signal. Surface EMGs were recorded on five subjects from the rectus abdominis, external oblique, and erector spinae muscles. These signals were then digitally high-pass filtered at cut-off frequencies of 10, 30, and 60 Hz. Integration and power analyses of the filtered EMGs were subsequently performed. It was found that an increase in the cut-off frequency affects the integrated EMG signal by (1) reducing the ECG contamination, (2) decreasing the amplitude, and (3) smoothing the signal. It was concluded that the use of a high-pass filter is effective in reducing ECG interference in integrated EMG recordings, and a cut-off frequency of approximately 30 Hz was optimal.RelevanceElectromyographic recordings of torso muscles are often used in the development of low-back biomechanical models. Unfortunately, these recordings are usually contaminated by electrocardiographic interference. High-pass filtering methods are sometimes used to diminish the influence of ECG from surface EMGs; however, the effects of these filters on the recorded and processed EMG have not been reported. The findings show that high-pass filtering is effective in reducing ECG contamination and motion artefact from integrated EMGs when the appropriate cut-off frequency is used. Inappropriate cut-off frequencies lead to either incomplete ECG removal or excess filtering of the EMG signal.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31029/1/0000706.pd

Angular displacement of torso during lifting: A system comparison of two measuring methods

This paper introduces a study which was conducted to evaluate two different methods used to measure trunk kinematics during a set of controlled lifting tasks. The following two methods were compared in a laboratory study: (1) an opto-electronic detection method using the Selspot 1 method, and (2) a new Miniature electronic Inclinometer method. The comparison revealed that, with care in calibration, the two methods display similar torso angle measurements for a large variety of test conditions. Cross-correlation between the angle estimates averaged (rmean = 0.814) for a combination of the following lifting variables: posture of lifting, lifting height, weight of load, and horizontal distance. Variation in the correlation coefficient between the two measuring methods shows acceptable positive correlation and consistent agreement in angle trajectory over time at Thoracic (at level 5), consistency was obtained at Lumbar (level 5) and Cervical (level 4) levels. Factors affecting the performance of the two measuring methods are analyzed and the pros and cons of the method are discussed. The findings argue for the use of the new Miniature Inclinometer since it is inexpensive when compared to the Selspot 1 measuring system, provides direct angle measurements and is an easy to use technique.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27669/1/0000051.pd

Lumbar muscle size and locations from CT scans of 96 women of age 40 to 63 years

Computed tomography scans of 96 women aged between 40 and 63 years were systematically measured to determine torso muscle moment arms and cross-sectional areas at L2/L3, L3/L4 and L4/L5 disc levels. The major findings were as follows: (1) the mean muscle moment arm and area data were not different bilaterally; (2) psoas, quadratus lumborum, and latissimus dorsi muscle moment arms consistently changed at the three disc levels, while erector spinae, rectus abdominis, transverse abdominis and the oblique muscles remained about the same distance from the three disc centroids; (3) psoas and quadratus lumborum muscles increased in mean size at the lower levels and (4 gross torso anthropometry and body weight had a significant (P r2 from 0[middle dot]12 to 0[middle dot]65) with the size of the erector spinae and psoas muscles, and with the moment arms of the rectus abdominis, transverse abdominis, latissimus dorsi, and oblique muscles.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28726/1/0000549.pd

Interpersonal interactions for haptic guidance during balance exercises

Background: Caregiver–patient interaction relies on interpersonal coordination during support provided by a therapist to a patient with impaired control of body balance. Research question: The purpose of this study was to investigate in a therapeutic context active and passive participant involvement during interpersonal support in balancing tasks of increasing sensorimotor difficulty. Methods: Ten older adults stood in semi-tandem stance and received support from a physical therapist (PT) in two support conditions: 1) physical support provided by the PT to the participant’s back via an instrumented handle affixed to a harness worn by the participant (“passive” interpersonal touch; IPT) or 2) support by PT and participant jointly holding a handle instrumented with a force-torque transducer while facing each other (“active” IPT). The postural stability of both support conditions was measured using the root-mean-square (RMS) of the Centre-of-Pressure velocity (RMS dCOP) in the antero-posterior (AP) and medio-lateral (ML) directions. Interpersonal postural coordination (IPC) was characterized in terms of cross-correlations between both individuals’ sway fluctuations as well as the measured interaction forces. Results: Active involvement of the participant decreased the participant’s postural variability to a greater extent, especially under challenging stance conditions, than receiving support passively. In the passive support condition, however, stronger in-phase IPC between both partners was observed in the antero-posterior direction, possibly caused by a more critical (visual or tactile) observation of participants’ body sway dynamics by the therapist. In-phase cross-correlation time lags indicated that the therapist tended to respond to participants’ body sway fluctuations in a reactive follower mode, which could indicate visual dominance affecting the therapist during the provision of haptic support. Significance: Our paradigm implies that in balance rehabilitation more partnership-based methods promote greater postural steadiness. The implications of this finding with regard to motor learning and rehabilitation need to be investigated

The household economic burden for acute coronary syndrome survivors in Australia

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.Background: Studies of chronic diseases are associated with a financial burden on households. We aimed to determine if survivors of acute coronary syndrome (ACS) experience household economic burden and to quantify any potential burden by examining level of economic hardship and factors associated with hardship. Methods: Australian patients admitted to hospital with ACS during 2-week period in May 2012, enrolled in SNAPSHOT ACS audit and who were alive at 18 months after index admission were followed-up via telephone/paper survey. Regression models were used to explore factors related to out-of-pocket expenses and economic hardship. Results: Of 1833 eligible patients at baseline, 180 died within 18 months, and 702 patients completed the survey. Mean out-of-pocket expenditure (n = 614) in Australian dollars was A$258.06 (median: A$126.50) per month. The average spending for medical services was A$120.18 (SD: A$310.35) and medications was A$66.25 (SD: A$80.78). In total, 350 (51 %) of patients reported experiencing economic hardship, 78 (12 %) were unable to pay for medical services and 81 (12 %) could not pay for medication. Younger age (18–59 vs ≥80 years (OR): 1.89), no private health insurance (OR: 2.04), pensioner concession card (OR: 1.80), residing in more disadvantaged area (group 1 vs 5 (OR): 1.77), history of CVD (OR: 1.47) and higher out-of-pocket expenses (group 4 vs 1 (OR): 4.57) were more likely to experience hardship. Conclusion: Subgroups of ACS patients are experiencing considerable economic burden in Australia. These findings provide important considerations for future policy development in terms of the cost of recommended management for patients

Widespread brain reorganization perturbs visuomotor coordination in early glaucoma

Glaucoma is the world’s leading cause of irreversible blindness, and falls are a major public health concern in glaucoma patients. Although recent evidence suggests the involvements of the brain toward advanced glaucoma stages, the early brain changes and their clinical and behavioral consequences remain poorly described. This study aims to determine how glaucoma may impair the brain structurally and functionally within and beyond the visual pathway in the early stages, and whether these changes can explain visuomotor impairments in glaucoma. Using multi-parametric magnetic resonance imaging, glaucoma patients presented compromised white matter integrity along the central visual pathway and around the supramarginal gyrus, as well as reduced functional connectivity between the supramarginal gyrus and the visual occipital and superior sensorimotor areas when compared to healthy controls. Furthermore, decreased functional connectivity between the supramarginal gyrus and the visual brain network may negatively impact postural control measured with dynamic posturography in glaucoma patients. Taken together, this study demonstrates that widespread structural and functional brain reorganization is taking place in areas associated with visuomotor coordination in early glaucoma. These results implicate an important central mechanism by which glaucoma patients may be susceptible to visual impairments and increased risk of falls

Implementation of a consumer-focused eHealth intervention for people with moderate-to-high cardiovascular disease risk: protocol for a mixed-methods process evaluation

Technology-mediated strategies have potential to engage patients in modifying unhealthy behaviour and improving medication adherence to reduce morbidity and mortality from cardiovascular disease (CVD). Furthermore, electronic tools offer a medium by which consumers can more actively navigate personal healthcare information. Understanding how, why and among whom such strategies have an effect can help determine the requirements for implementing them at a scale. This paper aims to detail a process evaluation that will (1) assess implementation fidelity of a multicomponent eHealth intervention; (2) determine its effective features; (3) explore contextual factors influencing and maintaining user engagement; and (4) describe barriers, facilitators, preferences and acceptability of such interventions.Methods and analysis: Mixed-methods sequential design to derive, examine, triangulate and report data from multiple sources. Quantitative data from 3 sources will help to inform both sampling and content framework for the qualitative data collection: (1) surveys of patients and general practitioners (GPs); (2) software analytics; (3) programme delivery records. Qualitative data from interviews with patients and GPs, focus groups with patients and field notes taken by intervention delivery staff will be thematically analysed. Concurrent interview data collection and analysis will enable a thematic framework to evolve inductively and inform theory building, consistent with a realistic evaluation perspective. Eligible patients are those at moderate-to-high CVD risk who were randomised to the intervention arm of a randomised controlled trial of an eHealth intervention and are contactable at completion of the follow-up period; eligible GPs are the primary healthcare providers of these patients.Ethics and dissemination: Ethics approval has been received from the University of Sydney Human Research Ethics Committee and the Aboriginal Health and Medical Research Council (AH&MRC) of New South Wales. Results will be disseminated via scientific forums including peer-reviewed publications and national and international conferences