Consistency in physiological stress responses and electromyographic activity during induced stress exposure in women and men

The Prediction of Stress in Radiation Therapy: Integrating Artificial Intelligence with Biological Signals

This study aimed to predict stress in patients using artificial intelligence (AI) from biological signals and verify the effect of stress on respiratory irregularity. We measured 123 cases in 41 patients and calculated stress scores with seven stress-related features derived from heart-rate variability. The distribution and trends of stress scores across the treatment period were analyzed. Before-treatment information was used to predict the stress features during treatment. AI models included both non-pretrained (decision tree, random forest, support vector machine, long short-term memory (LSTM), and transformer) and pretrained (ChatGPT) models. Performance was evaluated using 10-fold cross-validation, exact match ratio, accuracy, recall, precision, and F1 score. Respiratory irregularities were calculated in phase and amplitude and analyzed for correlation with stress score. Over 90% of the patients experienced stress during radiation therapy. LSTM and prompt engineering GPT4.0 had the highest accuracy (feature classification, LSTM: 0.703, GPT4.0: 0.659; stress classification, LSTM: 0.846, GPT4.0: 0.769). A 10% increase in stress score was associated with a 0.286 higher phase irregularity (p < 0.025). Our research pioneers the use of AI and biological signals for stress prediction in patients undergoing radiation therapy, potentially identifying those needing psychological support and suggesting methods to improve radiotherapy effectiveness through stress management.

Exploration of Emotion Dynamics Sensing Using Trapezius EMG and Fingertip Temperature

Exploration of the physiological signals associated with subjective emotional dynamics has practical significance. Previous studies have reported that the dynamics of subjective emotional valence and arousal can be assessed using facial electromyography (EMG) and electrodermal activity (EDA), respectively. However, it remains unknown whether other methods can assess emotion dynamics. To investigate this, EMG of the trapezius muscle and fingertip temperature were tested. These measures, as well as facial EMG of the corrugator supercilii and zygomatic major muscles, EDA (skin conductance level) of the palm, and continuous ratings of subjective emotional valence and arousal, were recorded while participants (n = 30) viewed emotional film clips. Intra-individual subjective-physiological associations were assessed using correlation analysis and linear and polynomial regression models. Valence ratings were linearly associated with corrugator and zygomatic EMG; however, trapezius EMG was not related, linearly or curvilinearly. Arousal ratings were linearly associated with EDA and fingertip temperature but were not linearly or curvilinearly related with trapezius EMG. These data suggest that fingertip temperature can be used to assess the dynamics of subjective emotional arousal.

Information discernment and online reading behaviour: an experiment

Purpose

This paper intends to explore the relationship between participants' eye fixations (a measure of attention) and durations (a measure of concentration) on areas of interest within a range of online articles and their levels of information discernment (a sub-process of information literacy characterising how participants make judgements about information).

Design/methodology/approach

Eye-tracking equipment was used as a proxy measure for reading behaviour by recording eye-fixations, dwell times and regressions in males aged 18–24 (n = 48). Participants' level of information discernment was determined using a quantitative questionnaire.

Findings

Data indicates a relationship between participants' level of information discernment and their viewing behaviours within the articles' area of interest. Those who score highly on an information discernment questionnaire tended to interrogate the online article in a structured and linear way. Those with high-level information discernment are more likely to pay attention to an article's textual and graphical information than those exhibiting low-level information discernment. Conversely, participants with low-level information discernment indicated a lack of curiosity by not interrogating the entire article. They were unsystematic in their saccadic movements spending significantly longer viewing irrelevant areas.

Social implications

The most profound consequence is that those with low-level information discernment, through a lack of curiosity in particular, could base their health, workplace, political or everyday decisions on sub-optimal engagement with and comprehension of information or misinformation (such as fake news).

Originality/value

Ground-breaking analysis of the relationship between a persons' self-reported level of information literacy (information discernment specifically) and objective measures of reading behaviour.

Stress Detection from Surface Electromyography using Convolutional Neural Networks

The study of stress and its implications has been the focus of interest in various fields of science. Many automated/semi-automated stress detection systems based on physiological markers have been gaining enormous popularity and importance in recent years. Such non-voluntary physiological features exhibit unique characteristics in terms of reliability, accuracy. Combined with machine learning techniques, they offer a great field of study of stress identification and modelling. In this study, we explore the use of Convolutional Neural Networks (CNN) for stress detection through surface electromyography signals (sEMG) of the trapezius muscle. One of the main advantages of this model is the use of the sEMG signal without computed features, contrary to classical machine learning algorithms. The proposed model achieved good results, with 73% f1-score for a multi-class classification and 82% in a bi-class classification.

The Influence of Neuroticism on the Muscle Response in the Trapezius and Frontalis Muscles to Anticipatory Stress

Abstract. Objective quantification of mental stress in the workplace would be beneficial for designing work tasks to avoid the negative consequences of mental stress. Methods such as surface electromyography have proven to be sensitive to mental demands. However, there is little knowledge about the muscle response and moderating factors during anticipatory stress paradigms. This study examined whether the personality dimension neuroticism moderates the muscle response to the expectation of an unpredictable electrical shock. Forty-seven subjects underwent three expectation phases, in which they could expect a pleasant audio signal (NoShock) or an electric shock in two conditions (anticipation of the first: Shock1, and second electric shock: Shock2) at an unpredictable moment. The frontalis muscle activity and the upper and upper/middle parts of the trapezius muscle were recorded using surface electromyography. Neuroticism was surveyed using the Big Five Inventory to assign the subjects to a group with lower or higher neuroticism. Shock1 only induced higher trapezius muscle activity in the higher neuroticism group, which vanished during Shock2, while the frontalis muscle showed no significant effects. The results suggest that neuroticism should be considered a moderating factor in assessing anticipatory stress using surface electromyography at the trapezius muscle.

Information discernment and the psychophysiological effects of misinformation

Purpose

The purpose of this paper is to determine to what extent a person’s psychophysiological well-being is affected by misinformation and whether their level of information discernment has any positive or negative effect on the outcome.

Design/methodology/approach

Participants (n = 48) were randomly and blindly allocated to one of two groups: control group participants were told a person they were working with was a student; experimental group participants were additionally led to believe that this other participant had extreme religious views. This was both stigmatising and misinforming, as this other person was an actor. Participants completed a pre-screening booklet and a series of tasks. Participants’ cardiovascular responses were measured during the procedure.

Findings

Participants with high levels of information discernment, i.e. those who are curious, use multiple sources to verify information, are sceptical about search engine information, are cognisant of the importance of authority and are aware that knowledge changes and is contradictory at times exhibited an adaptive stress response, i.e. healthy psychophysiological outcomes and responded with positive emotions before and after a stressful task.

Social implications

The findings indicate the potential harmful effects of misinformation and discuss how information literacy or Metaliteracy interventions may address this issue.

Originality/value

The first study to combine the hitherto unrelated theoretical areas of information discernment (a sub-set of information literacy), affective states (positive affect negative affect survey) and stress (challenge and threat cardiovascular measures).

Fatigue, Stress, and Performance during Alternating Physical and Cognitive Tasks-Effects of the Temporal Pattern of Alternations

In occupational life, performing cognitive work tasks in between fatiguing physical work tasks may allow recovery and reduce stress without losing productive working time. The temporal pattern of such alternations is likely a determinant of the recovery effect, influencing both stress and fatigue; the difficulty of the cognitive task (CT) would also be a likely determinant. The aim of this study was to determine to what extent the temporal pattern of alternations between a repetitive physical task and a CT of different difficulties influenced perceived fatigability, performance fatigability, stress-related outcomes, and performance. Fifteen women performed four work sessions comprising 110 min of repeated bouts of a repetitive physical task (pipetting), alternating with a CT (n-back). Sessions differed in bout cycle time (short: 7 + 3 min versus long: 14 + 6 min) and CT difficulty (CTdiff; easy versus difficult). Fatigue was assessed from recordings of maximal voluntary contraction force in shoulder elevations and handgrip pre- and post-work, electromyography (EMG) from the right trapezius and right forearm extensors during work, and repeated self-ratings of fatigue and pain throughout the session. Stress was assessed using electrocardiography (heart rate variability), salivary alpha-amylase, and self-reports. Perceived fatigue increased significantly over time for all protocols and more in long-cycle than short-cycle conditions. EMG activity did not increase markedly over time in any condition. Neither objective nor subjective indicators suggested that stress increased over time, regardless of the temporal pattern. Pipetting performance remained stable in all conditions. Cognitive performance, measured by the proportions of correct positive and false positive answers, differed between CTdiff levels but remained stable over time, with no significant difference between temporal patterns. In summary, temporal patterns of alternating tasks influenced fatigue to some extent but had no obvious influence on stress indicators or performance. Thus, designing job rotation with alternating physical and cognitive work should consider the temporal patterns of alternations to minimize fatigue.

Cardiac and Proprioceptive Accuracy Are Not Related to Body Awareness, Perceived Body Competence, and Affect

Interoception in the broader sense refers to the perception of internal states, including the perception of the actual state of the internal organs (visceroception) and the motor system (proprioception). Dimensions of interoception include (1) interoceptive accuracy, i.e., the ability to sense internal changes assessed with behavioral tests, (2) confidence rating with respect to perceived performance in an actual behavioral test, and (3) interoceptive sensibility, i.e., the self-reported generalized ability to perceive body changes. The relationship between dimension of cardioceptive and proprioceptive modalities and their association with affect are scarcely studied. In the present study, undergraduate students (N = 105, 53 males, age: 21.0 ± 1.87 years) filled out questionnaires assessing positive and negative affect (Positive and Negative Affect Schedule), interoceptive sensibility (Body Awareness Questionnaire), and body competence (Body Competence Scale of the Body Consciousness Questionnaire). Following this, they completed a behavioral task assessing cardioceptive accuracy (the mental heartbeat tracking task by Schandry) and two tasks assessing proprioceptive accuracy with respect to the tension of arm flexor muscles (weight discrimination task) and the angular position of the elbow joint (joint position reproduction task). Confidence ratings were measured with visual analog scales after the tasks. With the exception of a weak association between cardioceptive accuracy and the respective confidence rating, no associations between and within modalities were found with respect to various dimensions of interoception. Further, the interoceptive dimensions were not associated with state and trait positive and negative affect and perceived body competence. In summary, interoceptive accuracy scores do not substantially contribute to conscious representations of cardioceptive and proprioceptive ability. Within our data, non-pathological affective states (PANAS) are not associated with the major dimensions of interoception for the cardiac and proprioceptive modalities.

Stress-Related Responses to Alternations between Repetitive Physical Work and Cognitive Tasks of Different Difficulties

Alternating between physical and cognitive tasks has been proposed as an alternative in job rotation, allowing workers to recover from the physical work while still being productive. However, effects of such alternations on stress have not been investigated. This controlled experiment aimed at determining the extent to which stress-related responses develop during alternating physical and cognitive work, and to determine the extent to which cognitive task (CT) difficulty influences these responses. Fifteen women performed three sessions of 10 consecutive work bouts each including a seven-minute repetitive physical task (pipetting) and a three-minute CT (n-back) at one of three difficulty levels. Stress was assessed in terms of changes in heart rate variability, blood pressure, salivary alpha-amylase, salivary cortisol, perceived stress, and cognitive performance. The work session did not result in any marked stress response, and CT difficulty did not significantly influence stress, apart from alpha-amylase being higher at the easiest CT (F = 5.34, p = 0.02). Thus, according to our results, alternating between repetitive physical tasks and cognitive tasks may be a feasible alternative to classic job rotation between physical tasks only, even if the cognitive task is quite difficult. Future studies should address possible effects of the temporal pattern of alternations, and combine even other occupationally relevant tasks, preferably for extended periods of time.

Trapezius or facial muscles: Which one is more suitable for the measurement of stress using sEMG signals?

A number of techniques have been reported to detect mental stress. Surface Electromyography (sEMG) has also been used to measure stress by acquiring the signals from various sites of the human body, however, consensus need to be established to determine the best possible site to harvest stress related information. In this study, work related mental stress using sEMG signals acquired from trapezius muscle and facial muscles were compared. BIOPAC signal acquisition system was used to acquire sEMG signals simultaneously from both trapezius and facial muscles from forty five (45) healthy volunteers. Stress was induced using different standard methods in a controlled environment. Statistical significant difference was found between the stress and rest levels of sEMG signals. The statistical test also showed that the upper trapezius muscle was a better stress detection site as compared to facial muscles.Clinical Relevance- Optimized stress detection can help in the prevention of the possible stress related physical disorders.

Should we routinely assess psychological morbidities in idiopathic lower urinary tract dysfunction: ICI-RS 2019?

AIMS

Psychological morbidities play a major role in idiopathic lower urinary tract dysfunction (iLUTD). The aim of the Think Tank (TT) was to discuss the relevance of psychological morbidities in idiopathic LUTD over the life span, including overactive bladder (OAB) or dysfunctional voiding (DV) and methods of assessment.

METHODS

The paper is based on a selective review of the literature and in-depth discussions, leading to research recommendations regarding the assessment of psychological morbidities in iLUTD on children and adults held during the TT of the International Consultation on Incontinence Research Society in 2019.

RESULTS

Psychological comorbidities affect the health behaviors and treatment outcomes in patients with iLUTD. Both clinically relevant comorbid mental disorders, as well as subclinical psychological symptoms have a major impact and negatively influence incontinence treatment. Research is needed to elucidate mechanisms underlying iLUTD and psychological comorbidities. Clinical studies are needed to determine how perception generation and cognition impacts on the relationship of urinary perceptions, symptoms, and objective urodynamic function. Due to high psychological comorbidity rates, screening with validated, generic questionnaires for emotional and behavioral disorders in children with nocturnal enuresis, daytime urinary incontinence, and fecal incontinence is recommended. Brief screening is recommended for all adults with iLUTD, especially with OAB and DV, who are refractory to treatment.

CONCLUSIONS

Due to the high rate and relevance in clinical practice, screening for psychological comorbidities is recommended for all age groups. The research recommendations of this TT may be followed to improve the assessment of psychological morbidities in iLUTD.

Estimating Cognitive Workload in an Interactive Virtual Reality Environment Using EEG

With the recent surge of affordable, high-performance virtual reality (VR) headsets, there is unlimited potential for applications ranging from education, to training, to entertainment, to fitness and beyond. As these interfaces continue to evolve, passive user-state monitoring can play a key role in expanding the immersive VR experience, and tracking activity for user well-being. By recording physiological signals such as the electroencephalogram (EEG) during use of a VR device, the user's interactions in the virtual environment could be adapted in real-time based on the user's cognitive state. Current VR headsets provide a logical, convenient, and unobtrusive framework for mounting EEG sensors. The present study evaluates the feasibility of passively monitoring cognitive workload via EEG while performing a classical n-back task in an interactive VR environment. Data were collected from 15 participants and the spatio-spectral EEG features were analyzed with respect to task performance. The results indicate that scalp measurements of electrical activity can effectively discriminate three workload levels, even after suppression of a co-varying high-frequency activity.

Electromyographic analysis of upper trapezius, abductor pollicis longus and abductor pollicis brevis during smartphone use in different positions among young male and female subjects

BACKGROUND

Smartphone use has increased tremendously in recent times and there are various adverse musculoskeletal consequences associated with its use. Alteration in the activation patterns of muscles in certain positions may be the reason behind the development of musculoskeletal disorders in smartphone users; however, it has not been thoroughly investigated by the existing literature.

OBJECTIVES

To investigate the electromyographic (EMG) activity of upper trapezius (UT), abductor pollicis brevis (APB) and abductor pollicis longus (APL) during smartphone use in three different positions (standing, sitting on the chair and sitting cross legged on the floor) in young male versus female subjects.

METHODS

Twenty-six young male (age: 23.77 ± 2.47 years) and 26 young female (age: 22.45 ± 2.32 years) smartphone users were recruited from Centre for Physiotherapy and Rehabilitation Sciences, Jamia Millia Islamia, New Delhi, India. EMG activity of UT, APB and APL muscles was examined using surface electrodes during a smartphone task in three different positions, i.e. standing, sitting on a chair, sitting cross-legged on the floor. The smartphone task consisted of typing English quotations for 20 s 3 times with a rest period of 10 s between each quotation and a 5-min interval between each position, respectively.

RESULTS

EMG activity of the UT muscle was found to be significantly reduced when sitting on a chair as compared to standing (p < 0.001) and sitting cross-legged (p = 0.008) during smartphone use. APB and APL muscle activity were not significantly different between the three positions (p > 0.05). Moreover, the activation patterns of these muscles did not differ in male and female subjects (p > 0.05).

CONCLUSION

The present study demonstrates that the UT muscle is least activated when sitting on chair as compared to standing and sitting cross-legged during smartphone use. Moreover, the activity of neck and thumb muscles does not vary significantly between male and female subjects during smartphone use in different positions. As UT muscle activation significantly varies with the position of smartphone use, thus, the position adopted during smartphone use should be taken into consideration and the position which causes least strain on muscles, i.e. sitting on the chair should be adopted.

Sounds of Nature in the City: No Evidence of Bird Song Improving Stress Recovery

Noise from city traffic is one of the most significant environmental stressors. Natural soundscapes, such as bird songs, have been suggested to potentially mitigate or mask noise. All previous studies on masking noise use self-evaluation data rather than physiological data. In this study, while respondents (n = 117) watched a 360° virtual reality (VR) photograph of a park, they were exposed to different soundscapes and mild electrical shocks. The soundscapes—“bird song”, “bird song and traffic noise”, and “traffic noise”—were played during a 10 min recovery period while their skin conductance levels were assessed as a measure of arousal/stress. No significant difference in stress recovery was found between the soundscapes although a tendency for less stress in “bird song” and more stress in “traffic noise” was noted. All three soundscapes, however, significantly reduced stress. This result could be attributed to the stress-reducing effect of the visual VR environment, to the noise levels being higher than 47 dBA (a level known to make masking ineffective), or to the respondents finding bird songs stressful. Reduction of stress in cities using masking with natural sounds requires further studies with not only larger samples but also sufficient methods to detect potential sex differences.

A Randomized Controlled Trial in the Evaluation of a Novel Stress Management Tool: A Lounge Chair Experience

Objectives

The aim of this study was to compare the stress reduction effects of spending 25 minutes reclining in a SolTec™ Lounge between 2 intervention groups. Group 1 experienced the Lounge with multilayered music on an external speaker, while group 2 experienced the Lounge with multilayered music and synchronous vibration and magnetic stimulation from within the chair.

Subjects

In total, 110 participants with a self-reported stress level of 4 or higher on a 0- to 10-point scale were recruited from the local community including employees. Participants were randomized into receiving 1 of the 2 interventions. There were no significant differences between the group’s average stress levels prior to the interventions.

Interventions

Both groups received a 25-minute session in a dimly lit, quiet area on the Lounge with multilayered music. The second group also received vibration and magnetic stimulation that were synchronized with the music.

Design

Current stress level as well as ratings or feelings of anxiety, tenseness, energy, focus, happiness, relaxation, nervousness, creativeness, and being rested were recorded before and after the session.

Results

Both groups of participants reported equivalent decreased feelings of stress after using the Lounge. Participants receiving the synchronous multilayered music, vibration, and magnetic stimulation did report significantly reduced feelings of tenseness, feeling more relaxed, and feeling more creative when compared with the group that received music only.

Conclusion

Spending 25 minutes in the SolTec™ Lounge with multilayered music is an effective way to reduce self-reported stress in individuals who self-report having a high stress level. If confirmed by future studies, including synchronous vibration and magnetic stimulation with the multilayered music might be an effective stress reduction strategy.

Work stress and health problems of professional drivers: a hazardous formula for their safety outcomes

Background

Several empirical studies have shown that professional drivers are a vulnerable occupational group, usually exposed to environmental stressors and adverse work conditions. Furthermore, recent studies have associated work-related stress with negative job performances and adverse health outcomes within this occupational group, including cardiovascular diseases and unsafe vehicle operation.

Objective

The aim of this study was to describe the working conditions and the health status of this occupational group, and to evaluate the association between the Demand-Control model of job stress and their self-reported health and safety outcomes.

Methods

A pooled sample of 3,665 Colombian professional drivers was drawn from five different studies. The Job Content Questionnaire and the General Health Questionnaire were used to measure work stress and self-reported mental health, respectively. Additionally, professional drivers self-reported health problems (hypertension, dyslipidemia, diabetes and overweight) and health-related risky behaviors (smoking and sedentary behavior).

Results

Regarding the Job Demands-Control (JDC) model, it was found that approximately a third part of Colombian professional drivers suffer from high job strain (29.1%). Correlational and multivariate analyses suggest that de JDC model of stress is associated with the professional drivers' mental health, traffic accidents and fines, but not with other physical and behavioral health-related outcomes, which are highly prevalent among this occupational group, such as hypertension, dyslipidemia, diabetes, overweight, smoking and sedentary behavior.

Conclusion

The results of this study suggest that (a) stressful working conditions are associated with health and lifestyle-related outcomes among professional drivers, and (b) that evidence-based interventions are needed in order to reduce hazardous working conditions, job stress rates and their negative impact on the health of this occupational group.

The association between neck and shoulder discomfort-Katakori-and high somatizing tendency

Objectives: 'Katakori', discomfort or dull pain around the neck and shoulder, is common in Japan. Somatizing tendency is important in the quality of daily living. This study aimed to examine the association between disability due to Katakori and high somatizing tendency.Methods: This internet study included 34,754 Japanese adults who reported Katakori in the past four weeks. Katakori was classified into four grades: 1) no Katakori, 2) Katakori without difficulty in activities for daily living (ADL), 3) Katakori with ADL difficulty but without absence from social activities, and 4) Katakori with absence from social activities. Somatizing tendency was assessed using the Somatic Symptom Scale-8 (SSS-8). The association between a very high (SSS-8 ≥ 16) somatizing tendency and Katakori grade was examined using logistic regression adjusting for age, sex, body mass index, marital status, smoking, regular exercise, low back pain, depression, and the number of chronic conditions.Results: Katakori grade was significantly associated with a very high somatizing tendency (Odds ratio (OR)= 5.36 [4.36-6.60] in grade 4 vs. 2, and OR= 2.57 [2.30-2.89] in grade 3 vs. 2).Conclusion: When treating severe Katakori with disability, somatizing tendency should be assessed to facilitate better management.

Into the Wild: The Challenges of Physiological Stress Detection in Laboratory and Ambulatory Settings

Stress and mental health have become major concerns worldwide. Research has already extensively investigated physiological signals as quantitative and continuous markers of stress. In recent years, the focus of the field has shifted from the laboratory to the ambulatory environment. We provide an overview of physiological stress detection in laboratory settings with a focus on identifying physiological sensing priorities, including electrocardiogram, skin conductance, and electromyogram, and the most suitable machine learning techniques, of which the choice depends on the context of the application. Additionally, an overview is given of new challenges ahead to move toward the ambulant environment, including the influence of physical activity, lower signal quality due to motion artifacts, the lack of a stress reference, and the subject-dependent nature of the physiological stress response. Finally, several recommendations for future research are listed, focusing on large-scale, longitudinal trials across different population groups and just-in-time interventions to move toward disease prevention and interception.

Objective Evaluation of Performance Stress in Musicians With Focal Hand Dystonia: A Case Series

Five musicians suffering from focal dystonia participated in a pilot study that examined the feasibility of an experimental protocol designed to assess musicians' motor performance under stress. Electrocardiography, free cortisol levels, and subjective assessments were used to monitor alterations of the hypothalamic-pituitary-adrenal axis. As measures of motor outcome, temporal variability of finger movements and muscular cocontraction of the wrist flexor and extensor were assessed. Findings suggest that the specific experimental design could be successfully applied. Several methodological issues such as carryover effects, the use of free cortisol, the inclusion of a double baseline, and the classification of dystonic patients into stress responders and nonresponders are analyzed and discussed.

Impact of early life adversity on EMG stress reactivity of the trapezius muscle

Human and animal research indicates that exposure to early life adversity increases stress sensitivity later in life. While behavioral markers of adversity-induced stress sensitivity have been suggested, physiological markers remain to be elucidated. It is known that trapezius muscle activity increases during stressful situations. The present study examined to what degree early life adverse events experienced during early childhood (0-11 years) and adolescence (12-17 years) moderate experimentally induced electromyographic (EMG) stress activity of the trapezius muscles, in an experimental setting. In a general population sample (n = 115), an anticipatory stress effect was generated by presenting a single unpredictable and uncontrollable electrical painful stimulus at t = 3 minutes. Subjects were unaware of the precise moment of stimulus delivery and its intensity level. Linear and nonlinear time courses in EMG activity were modeled using multilevel analysis. The study protocol included 2 experimental sessions (t = 0 and t = 6 months) allowing for examination of reliability.Results show that EMG stress reactivity during the stress paradigm was consistently stronger in people with higher levels of early life adverse events; early childhood adversity had a stronger moderating effect than adolescent adversity. The impact of early life adversity on EMG stress reactivity may represent a reliable facet that can be used in both clinical and nonclinical studies.

α1- and α2-adrenergic receptors in the retrotrapezoid nucleus differentially regulate breathing in anesthetized adult rats

Norepinephrine (NE) is a potent modulator of breathing that can increase/decrease respiratory activity by α1-/α2-adrenergic receptor (AR) activation, respectively. The retrotrapezoid nucleus (RTN) is known to contribute to central chemoreception, inspiration, and active expiration. Here we investigate the sources of catecholaminergic inputs to the RTN and identify respiratory effects produced by activation of ARs in this region. By injecting the retrograde tracer Fluoro-Gold into the RTN, we identified back-labeled catecholaminergic neurons in the A7 region. In urethane-anesthetized, vagotomized, and artificially ventilated male Wistar rats unilateral injection of NE or moxonidine (α2-AR agonist) blunted diaphragm muscle activity (DiaEMG) frequency and amplitude, without changing abdominal muscle activity. Those inhibitory effects were reduced by preapplication of yohimbine (α2-AR antagonist) into the RTN. Conversely, unilateral RTN injection of phenylephrine (α1-AR agonist) increased DiaEMG amplitude and frequency and facilitated active expiration. This response was blocked by prior RTN injection of prazosin (α1-AR antagonist). Interestingly, RTN injection of propranolol (β-AR antagonist) had no effect on respiratory inhibition elicited by applications of NE into the RTN; however, the combined blockade of α2- and β-ARs (coapplication of propranolol and yohimbine) revealed an α1-AR-dependent excitatory response to NE that resulted in increase in DiaEMG frequency and facilitation of active expiration. However, blockade of α1-, α2-, or β-ARs in the RTN had minimal effect on baseline respiratory activity, on central or peripheral chemoreflexes. These results suggest that NE signaling can modulate RTN chemoreceptor function; however, endogenous NE signaling does not contribute to baseline breathing or the ventilatory response to central or peripheral chemoreceptor activity in urethane-anesthetized rats.

Potential risk factors for onset of severe neck and shoulder discomfort (Katakori) in urban Japanese workers

Katakori is a Japanese word, and there is no clear English translation. Katakori consists of two terms, Kata means neck and shoulder, kori means stiffness. Consequently, Katakori is defined as neck and shoulder discomfort or dull pain. Katakori is a major somatic complaint and has a large impact on workers. To examine the association between onset of severe Katakori and potential risk factors in Japanese workers, a prospective cohort study, entitled "Cultural and Psychosocial Influence on Disability (CUPID)", was conducted. Self-administered questionnaires were distributed twice: at baseline and 1 year after baseline. Logistic regression was used to explore the risk factors of onset of severe Katakori. Of those 1,398, the incidence of severe Katakori onset after 1 year was 3.0% (42 workers). Being female (adjusted odds ratio: 2.39, 95% confidence interval: 1.18-4.86), short sleep duration (adjusted odds ratio: 2.86, 95% confidence interval: 1.20-6.82) and depressed mood with some issues at work (adjusted odds ratio: 3.11, 95% confidence interval: 1.38-7.03) were significantly associated with onset of severe Katakori. Psychosocial factors as well as gender difference were associated with onset of severe Katakori. We suggest that mental health support at the workplace is important to prevent severe Katakori.

Development of statistical models for predicting muscle and mental activities during repetitive precision tasks

This study was conducted to develop muscle and mental activities on repetitive precision tasks. A laboratory experiment was used to address the objectives. Surface electromyography was used to measure muscle activities from eight upper limb muscles, while electroencephalography recorded mental activities from six channels. Fourteen university students participated in the study. The results show that muscle and mental activities increase for all tasks, indicating the occurrence of muscle and mental fatigue. A linear relationship between muscle activity, mental activity and time was found while subjects were performing the task. Thus, models were developed using those variables. The models were found valid after validation using other students' and workers' data. Findings from this study can contribute as a reference for future studies investigating muscle and mental activity and can be applied in industry as guidelines to manage muscle and mental fatigue, especially to manage job schedules and rotation.

Psychobiological stress reactivity and personality in persons with high and low stressor-induced extralaryngeal reactivity

PURPOSE

The purpose of the study was to determine whether persons who responded with high stressor-induced extralaryngeal muscle activity in a stress reactivity protocol differed from those with low muscle activity on measures of emotional and autonomic cardiovascular reactivity and personality.

METHOD

Thirty-six vocally healthy women (18-35 years) were assigned to high and low extralaryngeal groups based on submental (SM) and infrahyoid (IH) surface electromyography (sEMG) recordings obtained during a stress reactivity protocol (high vs. low sEMGSM and sEMGIH, n = 18 per subgroup; Dietrich & Verdolini Abbott, 2012). Measures included assessments of basic fear and fear of public speaking, rumination, systolic blood pressure (SBP), and personality.

RESULTS

The high sEMGIH group reported significantly greater basic fear across experimental phases than did the low sEMGIH group (p = .036). However, the high sEMGSM and sEMGIH versus low sEMGSM and sEMGIH groups did not differ on fear of public speaking, rumination, or SBP across phases. Both high sEMGSM and sEMGIH groups were characterized by significantly lower scores on Extraversion (p < .001).

CONCLUSION

In combination with the authors' previous findings (Dietrich & Verdolini Abbott, 2012), the present findings provided robust evidence that low Extraversion was linked to stressor-induced changes in extralaryngeal functioning and that perceived fear played a contributing role.

Safety climate, hardiness, and musculoskeletal complaints: a mediated moderation model

This study explores the mechanisms linking the psychosocial characteristics of the workplace with employees' work-related musculoskeletal complaints. Poor safety climate perceptions represent a stressor that may elicit frustration, and subsequently, increase employees' reports of musculoskeletal discomforts. Results from an employee sample supported that when employees' perceived safety was considered a priority, they experienced less frustration and reported fewer work-related upper body musculoskeletal symptoms. Psychological hardiness, a personality trait that is indicative of individuals' resilience and success in managing stressful circumstances, moderated these relationships. Interestingly, employees with high hardiness were more affected by poor safety climate.

Comparison of concepts in easy-to-use methods for MSD risk assessment

This article presents a comparative analysis of easy-to-use methods for assessing musculoskeletal load and the risk for developing musculoskeletal disorders. In all such methods, assessment of load consists in defining input data, the procedure and the system of assessment. This article shows what assessment steps the methods have in common; it also shows how those methods differ in each step. In addition, the methods are grouped according to their characteristic features. The conclusion is that the concepts of assessing risk in different methods can be used to develop solutions leading to a comprehensive method appropriate for all work tasks and all parts of the body. However, studies are necessary to verify the accepted premises and to introduce some standardization that would make consolidation possible.

Experimentally induced stress validated by EMG activity

Experience of stress may lead to increased electromyography (EMG) activity in specific muscles compared to a non-stressful situation. The main aim of this study was to develop and validate a stress-EMG paradigm in which a single uncontrollable and unpredictable nociceptive stimulus was presented. EMG activity of the trapezius muscles was the response of interest. In addition to linear time effects, non-linear EMG time courses were also examined. Taking into account the hierarchical structure of the dataset, a multilevel random regression model was applied. The stress paradigm, executed in N = 70 subjects, consisted of a 3-minute baseline measurement, a 3-minute pre-stimulus stress period and a 2-minute post-stimulus phase. Subjects were unaware of the precise moment of stimulus delivery and its intensity level. EMG activity during the entire experiment was conform a priori expectations: the pre-stimulus phase showed a significantly higher mean EMG activity level compared to the other two phases, and an immediate EMG response to the stimulus was demonstrated. In addition, the analyses revealed significant non-linear EMG time courses in all three phases. Linear and quadratic EMG time courses were significantly modified by subjective anticipatory stress level, measured just before the start of the stress task. Linking subjective anticipatory stress to EMG stress reactivity revealed that subjects with a high anticipatory stress level responded with more EMG activity during the pre-stimulus stress phase, whereas subjects with a low stress level showed an inverse effect. Results suggest that the stress paradigm presented here is a valid test to quantify individual differences in stress susceptibility. Further studies with this paradigm are required to demonstrate its potential use in mechanistic clinical studies.

Stressor-induced increase in muscle fatigability of young men and women is predicted by strength but not voluntary activation

This study investigated mechanisms for the stressor-induced changes in muscle fatigability in men and women. Participants performed an isometric-fatiguing contraction at 20% maximal voluntary contraction (MVC) until failure with the elbow flexor muscles. Study one (n = 55; 29 women) involved two experimental sessions: 1) a high-stressor session that required a difficult mental-math task before and during a fatiguing contraction and 2) a control session with no mental math. For some participants (n = 28; 14 women), cortical stimulation was used to examine mechanisms that contributed to muscle fatigability during the high-stressor and control sessions. Study two (n = 23; nine women) determined the influence of a low stressor, i.e., a simple mental-math task, on muscle fatigability. In study one, the time-to-task failure was less for the high-stressor session than control (P < 0.05) for women (19.4%) and men (9.5%): the sex difference response disappeared when covaried for initial strength (MVC). MVC force, voluntary activation, and peak-twitch amplitude decreased similarly for the control and high-stressor sessions (P < 0.05). In study two, the time-to-task failure of men or women was not influenced by the low stressor (P > 0.05). The greater fatigability, when exposed to a high stressor during a low-force task, was not exclusive to women but involved a strength-related mechanism in both weaker men and women that accelerated declines in voluntary activation and slowing of contractile properties.

Preliminary analysis of physiological changes of nursing students during training

Long-term exposure to stress has been associated with chronic diseases, depression, and immune disorders. The precise detection and assessment of stress depends on personalized physiological monitoring and assessment of influence of personal and workplace factors We monitored nursing students during training on a high fidelity simulator in the Real-time Physiological Monitoring Lab at the University of Alabama in Huntsville. In this paper we present the preliminary results of this pilot study. A total of 14 participants were recorded: 12 female and 2 male subjects, 23-46 years old with an average age of 32.8 years. We analyzed heart rate, Heart Rate Variability (HRV), respiration, and physical activity. The results indicate significant strain on subjects during simulation: heart rate increased 16.7%, from 82.8 to 96.6 bpm (p&#60;0.001), falling to a slightly increased level after the training session (84.9 bpm); Root Mean Square of Successive RR Differences (RMSSD) decreased from 38.9 ms to 37.7 ms; the breathing rate increased during the simulation from 16.9 to 17.7 breaths/min. Distractions also significantly influenced physiological parameters: the first telephone call increased heart rate on average 9 bpm (p&#60;0.001), while the second call increased heart rate 8.6 bpm (p&#60;0.001). The simulated patient-related events created even more prominent response; the average heart rate increased 17.4 bpm (p&#60;0.001) at the onset of "patient in crisis" event. Real-time wearable monitoring may provide assessment of occupational stress.

The influence of mental load on muscle tension

We examined the differences in muscle tension and in physiological measures depending on the type of mental task. Fifteen participants performed tests for sustained attention, vigilance and maintaining posture only. We analysed electromyogram (EMG) measures of extensor digitorum (ED), flexor carpi ulnaris (FU), deltoideus (DE) and trapezius (TR), and heart rate (HR) and respiratory frequency (RF). Measures indicated higher values for mental tasks than for maintained posture only with significant differences in all measures. The following relationships were also significant: between DE and physiological measures (HR and RF), between ED and the amplitude of EMG of the other three muscles, between FU and TR and between HR and RF. The results of this study showed that the relationship between mental demands and muscle tension was mostly reflected by tension in the arm and shoulder girdle muscles and, to a lesser degree, in forearm muscles.

PRACTITIONER SUMMARY

We focused on physiological and muscle tension measures differentiating work according to the level of mental demands. Differences in sustained attention, vigilance and maintaining posture only proved that mental demands were mostly reflected by tension in arm and shoulder girdle muscles and, to a lesser degree, in forearm muscles.

Psychological stress impairs short-term muscular recovery from resistance exercise

PURPOSE

The primary aim of this study was to determine whether chronic mental stress moderates recovery of muscular function, perceived energy, fatigue, and soreness in the first hour after a bout of strenuous resistance exercise.

METHODS

Thirty-one undergraduate resistance training students (age = 20.26 ± 1.34 yr) completed the Perceived Stress Scale and Undergraduate Stress Questionnaire (USQ; a measure of life event stress) and completed fitness testing. After 5 to 14 d of recovery, they performed an acute heavy-resistance exercise protocol (10-repetition maximum (RM) leg press test plus six sets: 80%-100% of 10 RM). Maximal isometric force (MIF) was assessed before exercise, after exercise, and at 20, 40, and 60 min postexercise. Participants also reported their levels of perceived energy, fatigue, and soreness. Recovery data were analyzed with hierarchical linear modeling growth curve analysis.

RESULTS

Life event stress significantly moderated linear (P = 0.013) and squared (P = 0.05) recovery of MIF. This relationship held even when the model was adjusted for fitness, workload, and training experience. Likewise, perceived stress moderated linear recovery of MIF (P = 0.023). Neither USQ nor Perceived Stress Scale significantly moderated changes in energy, fatigue, or soreness.

CONCLUSION

Life event stress and perceived stress both moderated the recovery of muscular function, but not psychological responses, in the first hour after strenuous resistance exercise.

Associations between neck and shoulder discomfort (Katakori) and job demand, job control, and worksite support

OBJECTIVES

To examine the association of neck and shoulder discomfort (Katakori) with somatization and work-related factors (job demand, job control, and worksite support) in Japanese workers.

METHODS

Cross-sectional data from 2,022 Japanese workers were analyzed using a logistic regression model to examine the association between Katakori and somatization. A multiple logistic regression model was used to examine the association between Katakori and work-related factors (long working hours, job control, and support from colleagues and supervisors) after adjusting for possible confounding factors.

RESULTS

The odds of Katakori were higher among respondents with somatic symptoms than among those without (OR = 2.81 and 95% CI 2.10-3.75 for 1 symptom vs. no symptoms; OR = 3.86 and 95% CI 2.92-5.12 for 2+ symptoms vs. no symptoms). Lack of worksite support was significantly associated with Katakori (adjusted OR = 2.62; 95% CI 1.79-3.83). Long working hours and a lack of job control were not significantly associated with Katakori.

CONCLUSIONS

Katakori may be a form of somatization. A significant association was observed between Katakori and lack of worksite support from colleagues or supervisors. An increase in the social support provided at work may decrease the prevalence of this condition and improve workers' well-being, but more research is needed to substantiate this hypothesis.

Muscle- and task-dependent responses to concurrent physical and mental workload during intermittent static work

Many workers experience combined physical and mental demands in their jobs, yet the contribution of these demands to the development of musculoskeletal disorders is unclear. The purpose of this study was to investigate muscle- and task-dependent responses to concurrent demands during intermittent static work. Twenty-four participants performed shoulder, wrist, and torso exertions at three levels of physical workload (PWL) in the absence (control) and presence (concurrent) of a mental arithmetic task. Compared to the control, concurrent demand conditions resulted in decreased muscle activity (4-9% decrease), increased cardiovascular load (2-4% increase), and impaired motor co-ordination (9-24% increase in force fluctuation). Furthermore, these outcomes were more prominent at higher PWL levels and within postural (shoulder and torso) muscles. Mental task performance exhibited greater interference with the physical task at low and high PWL levels. Thus, it may be important to consider these muscle- and task-specific interactions of concurrent demands during job design to address worker health and performance issues.

PRACTITIONER SUMMARY

Occupational tasks place both physical and mental demands on workers. These demands can adversely affect physiological responses and performance, and are muscle- and task-dependent. Findings from this research may facilitate the development of ergonomics interventions, such as task redesign and tool/workstation design, that may help reduce risk of workplace injuries.

Understanding the link between psychosocial work stressors and work-related musculoskeletal complaints

It is well established that psychosocial work stressors relate to employees' work-related musculoskeletal disorder (WRMSD) symptoms. Using a model investigating psychological strain as a mediator between work stressors and WRMSD complaints, this study demonstrated that high levels role conflict, low job control, and low safety-specific leadership are associated with increased employee strain. Strain, in turn, was related to higher levels of WRMSD symptoms of the wrist/hand, shoulders, and lower back. Partial mediation of some relationships was also found, suggesting that additional meditational mechanisms for the relationships between stressors and musculoskeletal symptoms are plausible. This work supports the notion that psychosocial stressors in the work environment have important links to employee health, especially WRMSDs.

Interactions of visual and cognitive stress

BACKGROUND

The objective of this research is to assess the ocular and muscular response to long-duration reading under different visual and cognitive difficulty levels.

METHODS

Thirty-five subjects, with 20/20 vision and without history of ocular pathology or cognitive deficits, participated in the study. Subjects read under different visual and cognitive difficulty levels for 6 (30-minute) conditions. Upper and lower orbicularis oculi, frontalis, and trapezius muscle activities were recorded using surface electromyography (EMG). Aperture size, pupil diameter, and pulse rate of the subjects were recorded with a video camera, pulse meter, and ISCAN eye tracker (ISCAN Inc.), respectively.

RESULTS

The results show that the texts read with a refractive error caused increased orbicularis oculi EMG power and reduced aperture size (P < 0.001). There was no statistically significant difference between the conditions for pulse rate, pupil diameter, or EMG activity of the frontalis and trapezius muscles with either visual or cognitive stress presented in this experiment.

CONCLUSION

Visual stress experienced due to reading under an induced refractive error is potentially mediated by a local mechanism, different from the mechanism underlying reading under low contrast or high cognitive demand.

A critical review on physical factors and functional characteristics that may explain a sex/gender difference in work-related neck/shoulder disorders

The objective of this paper is to critically review recent literature on physical and functional sex/gender (s/g) differences, with focus on physical determinants associated with neck/shoulder musculoskeletal injuries. It is well known that there are s/g differences in anthropometrical and functional body characteristics (e.g. size and strength). However, s/g differences may be wrongly attributed if data analysis does not include appropriate corrections (e.g. by strength for endurance). Recent literature on motor control shows that there may indeed be s/g differences in muscle coordination and movement strategies during upper limb tasks that are not currently explained by methodological inadequacies. Moreover, recent studies have shown differences between men and women in sensory hypersensitivity characteristics associated with neck/shoulder injuries. Taken together, the literature points to the importance of accounting for possible s/g differences at all levels of the biopsychosocial system in order to better understand sex- and gender-specific issues relevant to workplace health.

PRACTITIONER SUMMARY

This article critically reviews recent literature and a conceptual model highlighting s/g differences in physical and functional characteristics related to neck/shoulder musculoskeletal disorders (NSMSD). Findings have implications on understanding how personal factors may affect NSMSD risk. With better understanding, practitioners can make more appropriate decisions to prevent work-related NSMSD.

Effects of physical and mental task demands on cervical and upper limb muscle activity and physiological responses during computer tasks and recovery periods

The present study examined the effects of physical and mental workload during computer tasks on muscle activity and physiological measures. Activity in cervical postural muscles and distal forearm muscles, heart rate and blood pressure were compared among three tasks and rest periods of 15 min each in an experimental study design. Fourteen healthy pain-free adults participated (7 males, mean age = 23.2 ± 3.0 years) and the tasks were: (1) copy-typing ("typing"), (2) typing at progressively faster speed ("pacing"), (3) mental arithmetic plus fast typing ("subtraction"). Typing task was performed first, followed by the other two tasks in a random order. Median muscle activity (50th percentile) was examined in 5-min intervals during each task and each rest period, and statistically significant differences in the "time" factor (within task) and time × task factors was found in bilateral cervical erector spinae and upper trapezius muscles. In contrast, distal forearm muscle activity did not show any significant differences among three tasks. All muscles showed reduced activity to about the baseline level within first 5 min of the rest periods. Heart rate and blood pressure showed significant differences during tasks compared to baseline, and diastolic pressure was significantly higher in the subtraction than pacing task. The results suggest that cervical postural muscles had higher reactivity than forearm muscles to high mental workload tasks, and cervical muscles were also more reactive to tasks with high physical demand compared to high mental workload. Heart rate and blood pressure seemed to respond similarly to high physical and mental workloads.

Effects of static contraction and cold stimulation on cardiovascular autonomic indices, trapezius blood flow and muscle activity in chronic neck-shoulder pain

The aim of the present study was to investigate reactions in trapezius muscle blood flow (MBF), muscle activity, heart rate variability (HRV) and systemic blood pressure (BP) to autonomic tests in subjects with chronic neck-shoulder pain and healthy controls. Changes in muscle activity and blood flow due to stress and unfavourable muscle loads are known underlying factors of work-related muscle pain. Aberration of the autonomic nervous system (ANS) is considered a possible mechanism. In the present study, participants (n = 23 Pain, n = 22 Control) performed autonomic tests which included a resting condition, static hand grip test (HGT) at 30% of maximal voluntary contraction, a cold pressor test (CPT) and a deep breathing test (DBT). HRV was analysed in time and frequency domains. MBF and muscle activity were recorded from the upper trapezius muscles using photoplethysmography and electromyography (EMG). The pain group showed reduced low frequency-HRV (LF) and SDNN during rest, as well as a blunted BP response and increased LF-HRV during HGT (∆systolic 22 mm Hg; ∆LF(nu) 27%) compared with controls (∆systolic 27; ∆LF(nu) 6%). Locally, the pain group had attenuated trapezius MBF in response to HGT (Pain 122% Control 140%) with elevated trapezius EMG following HGT and during CPT. In conclusion, only HGT showed differences between groups in systemic BP and HRV and alterations in local trapezius MBF and EMG in the pain group. Findings support the hypothesis of ANS involvement at systemic and local levels in chronic neck-shoulder pain.

Electromyographic assessment of apple bucket intervention designed to reduce back strain

The authors previously developed an apple bucket that was modified by use of a hip belt to reduce muscle fatigue. The intervention of belt use was accepted by workers and shown not to interfere with productivity. However, use of this intervention did not appear to reduce muscle fatigue when measured by tests of voluntary muscle strength. The purpose of the present study was to evaluate the intervention's effect on muscle fatigue employing surface electromyographic (EMG) amplitude. Amplitude measurements on 15 muscles were taken from 10 laboratory volunteers who were carrying a full bucket of apples, once while wearing the intervention belt and once without the intervention. These measurements were taken for seven different postures (four angles of trunk flexion (0 degrees , 20 degrees , 45 degrees , 90 degrees ) and three raised-arm positions (both up, dominant up, non-dominant up)) common to apple harvest work. Participants were measured in these conditions both with the bucket carried in front and with the bucket carried to the side. Significant reductions in amplitude favouring the intervention were seen for 11 of the 15 muscles in models considering the four body flexion angles. Ten of these were of the middle and lower back. These control/intervention differences were seen with both bucket-carrying positions (front vs. side) and tended to increase with increasing flexion angle. In contrast, no significant intervention effects were observed in models considering treatment by arm-raised position. One significant main effect (upper trapezius, side bucket) showed an amplitude reduction in the treatment condition. Another main effect showing increased amplitude in the intervention condition use was observed in the dominant levator scapulae (side bucket). Thus, the use of the intervention belt reduces EMG amplitude among a number of mid- and lower-back muscles. This is suggestive of a protective effect against back strain.