Evaluating the Neural Underpinnings of Motivation for Walking Exercise.

OBJECTIVE: Motivation is critically important for rehabilitation, exercise, and motor performance, but its neural basis is poorly understood. Recent correlational research suggests that the dorsomedial prefrontal cortex (dmPFC) may be involved in motivation for walking activity and/or descending motor output. This study experimentally evaluated brain activity changes in periods of additional motivation during walking exercise and tested how these brain activity changes relate to self-reported exercise motivation and walking speed. METHODS: Adults without disability (N = 26; 65% women; 25 [standard deviation = 5] years old) performed a vigorous exercise experiment involving 20 trials of maximal speed overground walking. Half of the trials were randomized to include "extra-motivation" stimuli (lap timer, tracked best lap time, and verbal encouragement). Wearable near-infrared spectroscopy measured oxygenated hemoglobin responses from frontal lobe regions, including the dmPFC, primary sensorimotor, dorsolateral prefrontal, anterior prefrontal, supplementary motor, and dorsal premotor cortices. RESULTS: Compared with standard trials, participants walked faster during extra-motivation trials (2.43 vs 2.67 m/s; P < .0001) and had higher oxygenated hemoglobin responses in all tested brain regions, including dmPFC (+842 vs +1694 µM; P < .0001). Greater dmPFC activity was correlated with more self-determined motivation for exercise between individuals (r = 0.55; P = .004) and faster walking speed between trials (r = 0.18; P = .0002). dmPFC was the only tested brain region that showed both of these associations. CONCLUSION: Simple motivational stimuli during walking exercise seem to upregulate widespread brain regions. Results suggest that dmPFC may be a key brain region linking affective signaling to motor output. IMPACT: These findings provide a potential biologic basis for the benefits of motivational stimuli, elicited with clinically feasible methods during walking exercise. Future clinical studies could build on this information to develop prognostic biomarkers and test novel brain stimulation targets for enhancing exercise motivation (eg, dmPFC).

Insufficiencies in sensory systems reweighting is associated with walking impairment severity in chronic stroke: an observational cohort study.

Background: Walking and balance impairment are common sequelae of stroke and significantly impact functional independence, morbidity, and mortality. Adequate postural stability is needed for walking, which requires sufficient integration of sensory information between the visual, somatosensory, and vestibular centers. "Sensory reweighting" describes the normal physiologic response needed to maintain postural stability in the absence of sufficient visual or somatosensory information and is believed to play a critical role in preserving postural stability after stroke. However, the extent to which sensory reweighting successfully maintains postural stability in the chronic stages of stroke and its potential impact on walking function remains understudied. Methods: In this cross-sectional study, fifty-eight community-dwelling ambulatory chronic stroke survivors underwent baseline postural stability testing during quiet stance using the modified Clinical test of Sensory Interaction in Balance (mCTSIB) and assessment of spatiotemporal gait parameters. Results: Seventy-six percent (45/58) of participants showed sufficient sensory reweighting with visual and somatosensory deprivation for maintaining postural stability, albeit with greater postural sway velocity indices than normative data. In contrast, survivors with insufficient reweighting demonstrated markedly slower overground walking speeds, greater spatiotemporal asymmetry, and limited acceleration potential. Conclusion: Adequate sensory system reweighting is essential for chronic stroke survivors' postural stability and walking independence. Greater emphasis should be placed on rehabilitation strategies incorporating multisensory system integration testing and strengthening as part of walking rehabilitation protocols. Given its potential impact on outcomes, walking rehabilitation trials may benefit from incorporating formal postural stability testing in design and group stratification.

In search of the ideal periosteal flap for bone non-union: The chimeric fibula-periosteal flap.

Vascularised periosteal flaps may increase the union rates in recalcitrant long bone non-union. The fibula-periosteal chimeric flap utilises the periosteum raised on an independent periosteal vessel. This allows the periosteum to be inset freely around the osteotomy site, thereby facilitating bone consolidation. PATIENTS AND METHODS: Ten patients underwent fibula-periosteal chimeric flaps (2016-2022) at the Canniesburn Plastic Surgery Unit, UK. Preceding non-union 18.6 months, with mean bone gap of 7.5 cm. Patients underwent preoperative CT angiography to identify the periosteal branches. A case-control approach was used. Patients acted as their own controls, with one osteotomy covered by the chimeric periosteal flap and one without, although in two patients both the osteotomies were covered using a long periosteal flap. RESULTS: A chimeric periosteal flap was used in 12 of the 20 osteotomy sites. Periosteal flap osteotomies had a primary union rate of 100% (11/11) versus those without flaps at 28.6% (2/7) (p = 0.0025). Union occurred in the chimeric periosteal flaps at 8.5 months versus 16.75 months in the control group (p = 0.023). One case was excluded from primary analysis due to recurrent mycetoma. The number needed to treat = 2, indicating that 2 patients would require a chimeric periosteal flap to avoid one non-union. Survival curves with a hazard ratio of 4.1 were observed, equating to a 4 times higher chance of union with periosteal flaps (log-rank p = 0.0016). CONCLUSIONS: The chimeric fibula-periosteal flap may increase the consolidation rates in difficult cases of recalcitrant non-union. This elegant modification of the fibula flap uses periosteum that is normally discarded, and this adds to the accumulating data supporting the use of vascularised periosteal flaps in non-union.

The development of a scenario-based human-machine-environment-procedure (HMEP) classification scheme for the root cause analysis of helicopter accidents.

The current study analyzed the root causes of 22 helicopter accidents/incidents that took place between 1998 and 2019. Each root cause was coded using three commonly used classification models in aviation HFACS, ATSB, and IATA to identify recurring factors for better targeting of future prevention strategies. The frequency analysis revealed that not following procedure (22 observations), training inadequate or unavailable (17), inadequate regulatory oversight (17), inadequate procedure guidance (16), company management absent or deficient (10) and incorrect manuals/charts/checklists (9) were the most frequent contributing factors. Since none of the existing models could summarize the root causes of 22 occurrences effectively, a scenario-based human-machine-environment-procedure (HMEP) classification scheme was proposed to use organizational influences, people management, technical failure, procedure and document, and environment as the first-layer subcategories. The HMEP scheme was additionally applied to the analysis and coding of 4 helicopter accidents in the USA published by the NTSB. The HMEP scheme revealed that NTSB had identified a significantly greater number of root causes in the manufacturer design, manufacturing & documentation. Overall, HMEP can be used to guide the data collection during accident investigation and subsequently to aggregate aviation accidents to derive recurring factors and compare accident patterns in an efficient manner.

The relation between acute changes in the systemic inflammatory response and circulating thiamine and magnesium concentrations after elective knee arthroplasty.

Thiamine diphosphate (TDP) and magnesium are co-factors for key enzymes in human intermediary metabolism. However, their role in the systemic inflammatory response (SIR) is not clear. Therefore, the aim of the present study was to examine the relation between acute changes in the SIR and thiamine and magnesium dependent enzyme activity in patients undergoing elective knee arthroplasty (a standard reproducible surgical injury in apparently healthy individuals). Patients (n = 35) who underwent elective total knee arthroplasty had venous blood samples collected pre- and post-operatively for 3 days, for measurement of whole blood TDP, serum and erythrocyte magnesium, erythrocyte transketolase activity (ETKA), lactate dehydrogenase (LDH), glucose and lactate concentrations. Pre-operatively, TDP concentrations, erythrocyte magnesium concentrations, ETKA and plasma glucose were within normal limits for all patients. In contrast, 5 patients (14%) had low serum magnesium concentrations (< 0.75 mmol/L). On post-operative day1, both TDP concentrations (p < 0.001) and basal ETKA (p < 0.05) increased and serum magnesium concentrations decreased (p < 0.001). Erythrocyte magnesium concentrations correlated with serum magnesium concentrations (rs = 0.338, p < 0.05) and remained constant during SIR. Post-operatively 14 patients (40%) had low serum magnesium concentrations. On day1 serum magnesium concentrations were directly associated with LDH (p < 0.05), WCC (p < 0.05) and neutrophils (p < 0.01). Whole blood TDP and basal ETKA increased while serum magnesium concentrations decreased, indicating increased requirement for thiamine and magnesium dependent enzyme activity during SIR. Therefore, thiamine and magnesium represent potentially modifiable therapeutic targets that may modulate the host inflammatory response. Erythrocyte magnesium concentrations are likely to be reliable measures of status, whereas serum magnesium concentrations and whole blood TDP may not.ClinicalTrials.gov: NCT03554668.

Changes in Lumbo-Pelvic Coordination of Individuals With and Without Low Back Pain When Wearing a Hip Orthosis.

Individuals with low back pain demonstrate an abnormal lumbo-pelvic coordination compared to back-healthy individuals. This abnormal coordination presents itself as a reduction in lumbar contributions and an increase in pelvic rotations during a trunk forward bending and backward return task. This study investigated the ability of a hip orthosis in correcting such an abnormal lumbo-pelvic coordination by restricting pelvic rotation and, hence increasing lumbar contributions. The effects of the hip orthosis on the lumbo-pelvic coordination were investigated in 20 low back pain patients and 20 asymptomatic controls. The orthosis reduced pelvic rotation by 12.7° and increased lumbar contributions by 11%. Contrary to our expectation, orthosis-induced changes in lumbo-pelvic coordination were smaller in patients; most likely because our relatively young patient group had smaller unrestricted pelvic rotations compared to asymptomatic individuals. Considering the observed capability of a hip orthosis in causing the expected changes in lumbo-pelvic coordination when there is a relatively large pelvic contribution to trunk motion, application of a hip orthosis may provide a promising method of correcting abnormal lumbo-pelvic coordination, particularly among patients who demonstrate larger pelvic rotation, that warrants further investigation.

Models of the effect of teleoperation transmission delay on robot movement time.

Recent research of [Scholcover and Gillan ( 2018 )] has shown experimentally that system transmission delay has a linear effect on the time taken to perform a complex tracking task with a simple teleoperated robot. This note shows that, for the case of moving a robot through a straight path, this relationship is predicted. The result is a simple modification of Drury's law to take into account the system delay. This work extends the model for performance under intermittent illumination of Drury to the effects of fixed delays in task performance, occurring with teleoperated robots. In all cases, there was empirical evidence for the predicted linear relationship. Practitioner summary: When there is a delay in system response for robotic teleoperation between a control input and system output, movement time (MT) is increased and the increased times are linearly related to the system delay. This is true for zero and first-order control and for delays occurring before and after the control action.

Development of ergonomics audits for bagging, haul truck and maintenance and repair operations in mining.

The development and testing of ergonomics and safety audits for small and bulk bag filling, haul truck and maintenance and repair operations in coal preparation and mineral processing plants found at surface mine sites is described. The content for the audits was derived from diverse sources of information on ergonomics and safety deficiencies including: analysis of injury, illness and fatality data and reports; task analysis; empirical laboratory studies of particular tasks; field studies and observations at mine sites; and maintenance records. These diverse sources of information were utilised to establish construct validity of the modular audits that were developed for use by mine safety personnel. User and interrater reliability testing was carried out prior to finalising the audits. The audits can be implemented using downloadable paper versions or with a free mobile NIOSH-developed Android application called ErgoMine. Practitioner Summary: The methodology used to develop ergonomics audits for three types of mining operations is described. Various sources of audit content are compared and contrasted to serve as a guide for developing ergonomics audits for other occupational contexts.

Human factors/ergonomics implications of big data analytics: Chartered Institute of Ergonomics and Human Factors annual lecture.

In recent years, advances in sensor technology, connectedness and computational power have come together to produce huge data-sets. The treatment and analysis of these data-sets is known as big data analytics (BDA), and the somewhat related term data mining. Fields allied to human factors/ergonomics (HFE), e.g. statistics, have developed computational methods to derive meaningful, actionable conclusions from these data bases. This paper examines BDA, often characterised by volume, velocity and variety, giving examples of successful BDA use. This examination provides context by considering examples of using BDA on human data, using BDA in HFE studies, and studies of how people perform BDA. Significant issues for HFE are the reliance of BDA on correlation rather than hypotheses and theory, the ethics of BDA and the use of HFE in data visualisation.

Current UK practices in the management of subacromial impingement.

BACKGROUND: Controversy presently exists surrounding the management of patients with subacromial impingement. This study aims to highlight current UK practices in the management of these patients. METHODS: BESS members were invited to complete a questionnaire and responses were received from 157 consultant shoulder surgeons. RESULTS: Physiotherapy is an integral part of management for 93% of surgeons with a minimum period of 12 weeks being most popular prior to consideration of arthroscopic subacromial decompression. Subacromial steroid injection is used by 95% and 86% repeat this if the patient has failed to respond to a previous injection by the general practioner. From initial presentation, 77% felt there should be at least 3 months of conservative management before proceeding to surgery. Good but transient response to subacromial injection was considered the best predictor of good surgical outcome by 77%. The coracoacromial ligament is fully released by 78%, although there was greater variation in how aggressive surgeons were with acromioplasty. Most (59%) do not include the nontender acromioclavicular joint to any extent in routine acromioplasty. Hospital physiotherapy protocols are used by 63% for postoperative rehabilitation. CONCLUSIONS: Variation exists in the management regimes offered to patients with subacromial impingement, but most employ a minimum period of 12 weeks of conservative management incorporating physiotherapy and at least 2 subacromial steriod injections.

Component rotational alignment in unexplained painful primary total knee arthroplasty.

BACKGROUND: Rotational malalignment of the components in total knee arthroplasty (TKA) can be a factor in poor outcomes but has yet to be defined. This study compares the rotational alignment of components in a cohort of 56 patients with unexplained pain following total knee arthroplasty with a matched control cohort of 56 patients with cemented Nex Gen Legacy posterior stabilised (LPS) flex fixed bearing TKA between March 2006 and May 2010. The aim of the study was to define an acceptable limit of rotation in total knee replacement. METHODS: Rotational alignment was calculated using the Berger protocol with post operative computerised tomography scanning. The alignment parameters measured were tibial and femoral component rotations and the combined component rotations and the component rotational mismatch. RESULTS: The two cohorts were demographically matched. Excessive internal rotation of the components was defined using the tenth percentile of rotations in the control cohort. Values of excessive internal rotation were 5.8° of the tibial component, 3.9° of the femoral component, 8.7° of combined rotation and 5.6° of the component mismatch. No significant difference was identified in excessive external rotation in any of the parameters. A significant difference in the mean rotations between the two cohorts was identified with internal rotation of the components in the painful cohort and external rotation on the control cohort. CONCLUSIONS: We identified internal rotation malalignment of the tibial (p=0.0003) and femoral (p=0.014) components individually as well as the combined component rotation (p=0.0003) and component rotation mismatch (p=0.0001) to be a factor in pain following TKA. External rotation of any of the component parameters was not identified to be a factor in painful TKA. This study adds to the understanding of rotational alignment in TKA and suggests limits of internal rotation alignment associated with painful Nex Gen Legacy posterior stabilised (LPS) flex fixed bearing TKA. LEVEL OF EVIDENCE: Level III.

Verification of models for ballistic movement time and endpoint variability.

A hand control movement is composed of several ballistic movements. The time required in performing a ballistic movement and its endpoint variability are two important properties in developing movement models. The purpose of this study was to test potential models for predicting these two properties. Twelve participants conducted ballistic movements of specific amplitudes using a drawing tablet. The measured data of movement time and endpoint variability were then used to verify the models. This study was successful with Hoffmann and Gan's movement time model (Hoffmann, 1981; Gan and Hoffmann 1988) predicting more than 90.7% data variance for 84 individual measurements. A new theoretically developed ballistic movement variability model, proved to be better than Howarth, Beggs, and Bowden's (1971) model, predicting on average 84.8% of stopping-variable error and 88.3% of aiming-variable errors. These two validated models will help build solid theoretical movement models and evaluate input devices. PRACTITIONER SUMMARY: This article provides better models for predicting end accuracy and movement time of ballistic movements that are desirable in rapid aiming tasks, such as keying in numbers on a smart phone. The models allow better design of aiming tasks, for example button sizes on mobile phones for different user populations.

Predictive models of safety based on audit findings: Part 2: Measurement of model validity.

Part 1 of this study sequence developed a human factors/ergonomics (HF/E) based classification system (termed HFACS-MA) for safety audit findings and proved its measurement reliability. In Part 2, we used the human error categories of HFACS-MA as predictors of future safety performance. Audit records and monthly safety incident reports from two airlines submitted to their regulatory authority were available for analysis, covering over 6.5 years. Two participants derived consensus results of HF/E errors from the audit reports using HFACS-MA. We adopted Neural Network and Poisson regression methods to establish nonlinear and linear prediction models respectively. These models were tested for the validity of prediction of the safety data, and only Neural Network method resulted in substantially significant predictive ability for each airline. Alternative predictions from counting of audit findings and from time sequence of safety data produced some significant results, but of much smaller magnitude than HFACS-MA. The use of HF/E analysis of audit findings provided proactive predictors of future safety performance in the aviation maintenance field.

Predictive models of safety based on audit findings: Part 1: Model development and reliability.

This consecutive study was aimed at the quantitative validation of safety audit tools as predictors of safety performance, as we were unable to find prior studies that tested audit validity against safety outcomes. An aviation maintenance domain was chosen for this work as both audits and safety outcomes are currently prescribed and regulated. In Part 1, we developed a Human Factors/Ergonomics classification framework based on HFACS model (Shappell and Wiegmann, 2001a,b), for the human errors detected by audits, because merely counting audit findings did not predict future safety. The framework was tested for measurement reliability using four participants, two of whom classified errors on 1238 audit reports. Kappa values leveled out after about 200 audits at between 0.5 and 0.8 for different tiers of errors categories. This showed sufficient reliability to proceed with prediction validity testing in Part 2.

Comment on "Visual layout modulates Fitts's law: the importance of first and last positions".

Pratt, Adam, and Fischer (2007) investigated the effect of surrounding targets on the time it took to move to an individual target and found that the movement time to a central target was above the Fitts's law line related to the first and last targets. They explained their results in terms of a "visuomotor hypothesis." Here, an alternative explanation is given in terms of a previously validated model of the "available target width" that is determined by the size of the target and the width of the finger pad that is being used to hit the target.

Performance in one-, two- and three-dimensional terminal aiming tasks.

Arm movement times were measured to targets with independent constraints (target sizes) in one, two or three directions (width, height and depth). In each case, modified forms of Fitts' law give a good fit to the data, with the best form being dependent on all constraints in the 'Weighted Euclidean' model of Accot, J. and Zhai, S., 2003. (Refining Fitts' law models for bivariate pointing. Proceedings of the SIGCHI conference on Human factors in computing systems CHI '03, 5-10 April 2003, Ft. Lauderdale, FL. New York: ACM Press, 193-200). The best predictor includes all the individual ratios of amplitude of movement to target dimension related to the various constraints, with the maximum portion of variance accounted for by the index of difficulty (ID) in the direction of motion. The suggestion by various authors that the maximum of the ID associated with the different constraints will determine the movement times is only partially successful. An explanation for the results is given in terms of control strategy and the form of target. STATEMENT OF RELEVANCE: In many tasks, workers move objects into limited spaces that allow only a single entry area. Termination of the movement may have constraints in one, two or three dimensions. Movement times for such tasks are important to predict industrial performance, and guide task designers in reducing physical constraints on performance.

Change of search time and non-search time in X-ray baggage screening due to training.

As found in studies of aircraft structural inspection, the time used for judging if a part of an aircraft shows tiny cracks is composed of search time, used for actively scanning, and non-search time, used for matching and decision while fixating a region of interest (Drury et al. 1997). These findings can be applied to detection of threats by X-ray screening of passenger bags at airports. To investigate whether search time and non-search time change when an experienced screener is given additional training in recognising threat objects in passenger bags, data from a European airport were analysed. A comparison of detection performance and reaction time between two large groups of screeners, one trained for 6 months, shows a large impact of training on overall performance and on both search and non-search components of the task. There was also a small but consistent decline in performance measures with screener age. This study shows a way to localise the effect of training on threat detection performance for aviation security screening. Analysis of the time needed for screening each passenger bag showed that training had a significant effect, particularly on the non-search part of the searching process (i.e. identification, recognition, decision, response execution, etc.).

The impact of joint responses of devices in an airport security system.

In this article, we consider a model for an airport security system in which the declaration of a threat is based on the joint responses of inspection devices. This is in contrast to the typical system in which each check station independently declares a passenger as having a threat or not having a threat. In our framework the declaration of threat/no-threat is based upon the passenger scores at the check stations he/she goes through. To do this we use concepts from classification theory in the field of multivariate statistics analysis and focus on the main objective of minimizing the expected cost of misclassification. The corresponding correct classification and misclassification probabilities can be obtained by using a simulation-based method. After computing the overall false alarm and false clear probabilities, we compare our joint response system with two other independently operated systems. A model that groups passengers in a manner that minimizes the false alarm probability while maintaining the false clear probability within specifications set by a security authority is considered. We also analyze the staffing needs at each check station for such an inspection scheme. An illustrative example is provided along with sensitivity analysis on key model parameters. A discussion is provided on some implementation issues, on the various assumptions made in the analysis, and on potential drawbacks of the approach.

Human factors in industrial systems: 40 years on.

OBJECTIVE: I evaluate the contribution of a pioneering Human Factors special issue on human factors in industrial systems. BACKGROUND: Papers on the content of the journal's first 10 years showed that industrial human factors/ergonomics (HF/E) in 1969 was quite a rarity in the journal and the society. METHOD: The 12 papers in the special issue are reviewed briefly and show a wide range of topics, including traditional industrial engineering, physical HF/E, and more mainstream applications of HF/E in this domain similar to those in military and aerospace domains. The evaluation is through citations, later journal content, society technical group membership, and specific influences of Harris's own paper in the issue. RESULTS: The expected direct citation influence of this special issue was not found: Citation counts were in line with all papers in Human Factors. However, other journals have been founded in North America that serve industrial HF/E and provide an outlet for more papers per year than Human Factors. In addition, the industrial domain is well represented in the Human Factors and Ergonomics Society. Finally, Harris's paper has been influential in the specific area of HF/E in inspection. CONCLUSIONS: Industrial HF/E is now more accepted within the HF/E community, although largely in the physical ergonomics subspecialty. APPLICATION: There is now evidence of use of HF/E techniques more broadly in industry, including service as well manufacturing enterprises.

Biomechanical, physiological and psychophysical evaluations of clean room boots.

The purpose of this study was to evaluate the significance of boot sole properties on reducing fatigue, to evaluate the effects of load carrying and walking (over a 1 h period) on biomechanical, physiological and psychophysical responses, and to investigate the correlations between the measurements. The results indicated that elasticity and shock absorption of the boot had significant effects on outcome variables. Significant load effects were seen in most measurements. All of the significant time period effects gave strong regressions, with no R2 value less than 0.983. The findings of this study provide useful information for the selection and design of clean room boots as well as for job design for load carrying tasks in the clean room environment.