Joakim Dahlman

Physiological responses to low-force work and psychosocial stress in women with chronic trapezius myalgia

BackgroundRepetitive and stressful work tasks have been linked to the development of pain in the trapezius muscle, although the underlying mechanisms still remain unclear. In earlier studies, it has been hypothesized that chronic muscle pain conditions are associated with imbalance in the autonomic nervous system, predominantly expressed as an increased sympathetic activity. This study investigates whether women with chronic trapezius myalgia show higher muscle activity and increased sympathetic tone at baseline and during repetitive low-force work and psychosocial stress, compared with pain-free controls.MethodsEighteen women with chronic trapezius myalgia (MYA) and 30 healthy female controls (CON) were studied during baseline rest, 100 min of repetitive low-force work, 20 min of psychosocial stress (Trier Social Stress Test, TSST), and 80 min recovery. The subjects rated their pain intensity, stress and energy level every 20 min throughout the experiment. Muscle activity was measured by surface electromyography in the trapezius muscle (EMGtrap) and deltoid muscle (EMGdelt). Autonomic reactivity was measured through heart rate (HR), skin conductance (SCL), blood pressure (MAP) and respiration rate (Resp).ResultsAt baseline, EMGtrap, stress ratings, and HR were higher in MYA than in CON. Energy ratings, EMGdelt, SCL, MAP and Resp were, however, similar in the two groups. Significant main group effects were found for pain intensity, stress ratings and EMGtrap. Deltoid muscle activity and autonomic responses were almost identical in MYA and CON during work, stress and recovery. In MYA only, pain intensity and stress ratings increased towards the end of the repetitive work.ConclusionWe found increased muscle activity during uninstructed rest in the painful muscle of a group of women with trapezius myalgia. The present study could not confirm the hypothesis that chronic trapezius myalgia is associated with increased sympathetic activity. The suggestion of autonomic imbalance in patients with chronic local or regional musculoskeletal pain needs to be further investigated.

Salivary cortisol response to acute stress and its relation to psychological factors in women with chronic trapezius myalgia-A pilot study

This study investigated differences in HPA axis function, measured as salivary cortisol concentrations, between 18 women with chronic trapezius myalgia (MYA) and 30 healthy female controls (CON). In addition, the interactions between HPA axis reactions to psychosocial stress and aspects of pain, health and psychological symptoms were analyzed. Salivary cortisol was measured both in daily life, to assess the circadian profile, and in the laboratory during light repetitive work and standardized psychosocial stress (Trier Social Stress Test, TSST). MYA and CON exhibited similar circadian rhythms and comparable salivary cortisol response magnitudes after TSST. In subjects defined as responders to the TSST, the mean peak time point of the cortisol response after TSST differed significantly between MYA and CON. Furthermore, negative psychological states and higher pain intensity were related to a slower HPA axis response to TSST. Low circadian variations in cortisol and smaller cortisol responses to TSST were found among subjects scoring high on anxiety sensitivity. Thus, a relatively favorable sample of female chronic trapezius myalgia patients exhibited normal circadian rhythm and normal salivary cortisol response magnitudes after a psychosocial stress test. In the subgroup of responders, the MYA group showed indications of a slower salivary cortisol response to psychosocial stress. Further studies are needed to elucidate the possibility of altered HPA axis activity in terms of a slower salivary cortisol response.

Performance and autonomic responses during motion sickness.

Objective: The aim of the study was to investigate how motion sickness, triggered by an optokinetic drum, affects short-term memory performance and to explore autonomic responses to perceived motion sickness. Background: Previous research has found that motion sickness decreases performance, but it is not known how short-term memory in particular is affected. Method: Thirty-eight healthy participants performed a listening span test while seated in a rotating optokinetic drum. Measurements of motion sickness, performance, heart rate, skin conductance, blood volume pulse, and pupil size were performed simultaneously throughout the experiment. Results: A total of 16 participants terminated the trial because of severe nausea, and the other 22 endured the full 25 min. Perceived motion sickness increased over time in both groups but less among those who endured the trial. Short-term memory performance decreased toward the end for those who terminated but increased in the other group. Results from the measured autonomic responses were ambiguous. Conclusion: We conclude that performance, measured as short-term memory, declines as perceived motion sickness progresses. Application: This research has potential implications for command and control personnel at risk of developing motion sickness.

Exploring non-technical miscommunication in vessel traffic service operation

Vessel traffic services (VTS) are maritime traffic monitoring systems used in port approaches, confined or congested waters. VTS operators (VTSOs) monitor a specific geographical area and support and direct ships that sail through the area, primarily making the navigating officer or pilot of each ship aware of the current traffic situation, local weather and geographical conditions. We used an interactive mid-fidelity simulation as a knowledge eliciting tool to explore the work situation of VTSOs. During the simulation, VTSOs from a VTS centre in Sweden ran a scenario based on a normal traffic situation in their local fairway. Results indicate that the VTSOs, even though they are well aware of crucial events in the fairway, at times choose not to inform navigating officers or pilots of these safety aspects apart from when subject to protocol. The present paper put forward elements behind this form of miscommunication and presents results indicating that the major contributing factor is the VTSOs’ anticipation of negative attitudes between working groups participating in the VTS system and the lack of sufficient regulation with regard to the role and responsibilities of VTSOs.

Could sound be used as a strategy for reducing symptoms of perceived motion sickness

BackgroundWorking while exposed to motions, physically and psychologically affects a person. Traditionally, motion sickness symptom reduction has implied use of medication, which can lead to detrimental effects on performance. Non-pharmaceutical strategies, in turn, often require cognitive and perceptual attention. Hence, for people working in high demand environments where it is impossible to reallocate focus of attention, other strategies are called upon. The aim of the study was to investigate possible impact of a mitigation strategy on perceived motion sickness and psychophysiological responses, based on an artificial sound horizon compared with a non-positioned sound source.MethodsTwenty-three healthy subjects were seated on a motion platform in an artificial sound horizon or in non-positioned sound, in random order with one week interval between the trials. Perceived motion sickness (Mal), maximum duration of exposure (ST), skin conductance, blood volume pulse, temperature, respiration rate, eye movements and heart rate were measured continuously throughout the trials.ResultsMal scores increased over time in both sound conditions, but the artificial sound horizon, applied as a mitigation strategy for perceived motion sickness, showed no significant effect on Mal scores or ST. The number of fixations increased with time in the non-positioned sound condition. Moreover, fixation time was longer in the non-positioned sound condition compared with sound horizon, indicating that the subjects used more time to fixate and, hence, assumingly made fewer saccades.ConclusionA subliminally presented artificial sound horizon did not significantly affect perceived motion sickness, psychophysiological variables or the time the subjects endured the motion sickness triggering stimuli. The number of fixations and fixation times increased over time in the non-positioned sound condition.

Evacuation in Practice - Observations from Five Full Scale Exercises

Evacuating a ship is a difficult task which normally is performed under severe and demanding conditions, exposing both crew members and passengers on board to an extreme and demanding situation. To be prepared for an incident happening on board and shouldering this responsibility is part of the everyday reality of the crew members’ work situation. This study reports the results from observations made on board five passenger ships performing full scale exercises with participants acting as passengers. The results pointed out four problem areas; the safety organization, the ability to perform tasks, the handling of life vests and communication. These areas represented an uncertainty in the requirements associated with the crew members’ role in the safety organization implied. There was also evidence of difficulties in the crews’ performing of different tasks, problems with donning life vests and insufficient communication. The crew member groups on board differ in their skills and knowledge to handle an evacuation situation. These groups need to be studied separately and systematically in order to determine how they comprehend their work situation and what their needs of preparation and training are in order to feel content with meeting the demands of their role in the safety organization.

Effects of Motion Sickness on Encoding and Retrieval Performance and on Psychophysiological Responses

Objective: In this study, possible effects of motion sickness on encoding and retrieval of words were investigated. Background: The impact of motion sickness on human performance has been studied w ...

Information and Repetition Change Children's Visual Strategies When Viewing Magic Tricks With and Without Gaze Cues

Gaze cues and direct gaze attract visual attention. However, few studies have explored visual cues in children within realistic contexts. The effect of information and repetitive stimulus presentation has not been thoroughly studied with dynamic stimuli. The aim of the present study was to investigate how information affects the visual strategies of children measured by the number of fixations on certain areas of interest and their durations. Furthermore, this study examined the effect of gaze cues and direct gaze. In two consecutive experiments, childrens visual strategies when viewing magic tricks were measured by an eye tracker. Gaze cues were only present in Experiment 1. The results showed that repetitive stimulus presentation and information caused children to change their visual strategies when viewing magic tricks with and without gaze cues. However, the effect was larger when the gaze cues were not present. These findings in children were similar to those in adults.

A case study of user adherence and software project performance barriers from a sociotechnical viewpoint

A marine propeller company and a technical university collaborated to optimize the company’s existing propeller design software. This paper reviews the project based on a sociotechnical perspective to organizational change on (a) how the university-company project and user involvement were organized, and (b) what the main management barriers were and why they may have occurred. Fieldwork included interviews and observations with university and company stakeholders over thirteen months. The data was analyzed and sorted into themes describing the barriers, such as lack of a planned strategy for deliverables or resource use in the project; the users exhibited low adherence towards the optimized software, as well as there was limited time and training allocated for them to test it. Lessons learned suggest clarifying stakeholder roles and contributions, and engaging the users earlier and beyond testing the software for malfunctions to enhance knowledge mobilization, involve them in the change and increase acceptance.

Development of a Behavioural Marker System for Rating Cadet ’ s Non- Technical Skills

Despite the adoption of crew resource management training for bridge teams over the last decades, the training is still heavily focussed on technical achievements. In an educational context, the situation is more problematical, since with requirement of developing the technical skills, there is a need to build and evaluate the non-technical skills of cadets with little experience in bridge team management. In parallel with the application of team leadership models, the Portuguese Naval Academy conducted a research to improve the development and assessment of non-technical skills in bridge simulators. This paper describes the method used to identify the key non-technical skills required for naval cadets and to develop a behavioural marker system for their measurement. A literature review of behavioural marker systems was supplemented with an analysis of interviews conducted with students and simulator instructors. Additionally, further analysis of Portuguese Navy accidents reports was made, applying the HFACS framework to identify the relevant non-technical skills involved in the accidents. The resulting rating system covers five skill categories (leadership, situational awareness, communication, team work and decision making), each one with three rating elements. The framework is currently under evaluation tests in bridge simulators sessions, within an educational context.