The influence of mental load on muscle tension

Prevalence of musculoskeletal pain and dysfunction in electrical utility workers: Practical considerations for prevention and rehabilitation in the workplace

INTRODUCTION

This study assessed the prevalence and associations of musculoskeletal pain and dysfunction in electrical utility workers, with the aim of applying the findings to better prevent and rehabilitate workplace musculoskeletal disorders.

METHODS

Employees completed an online survey recording their musculoskeletal symptoms across nine anatomical locations for the preceding 12 months. A total of 565 employees, working across eight different electrical utility organisational work units, completed the survey.

CONSUMER AND COMMUNITY INVOLVEMENT

The study was collaborative and conducted in Australia's largest, wholly government owned electricity company. The study originated from the participating organisation wanting to better understand their musculoskeletal disorder (MSD) risks.

RESULTS

Employees who experienced high job stress were 4.06 times (95% confidence interval [CI] = 1.78-9.29) more likely to report musculoskeletal symptoms in the shoulder compared with employees with lower reported job stress. Employees that perceived their work to have high physical demands report lower back musculoskeletal symptoms at 2.64 times the rate of those perceiving their job to be of low physical demand (95% CI = 1.44-4.84). There were significant differences in the lower back musculoskeletal symptoms according to work unit membership.

CONCLUSIONS

Understanding the prevalence of MSDs is critical to implementing practical prevention and rehabilitation strategies in the workplace. This anonymous survey highlighted that a large proportion of electrical utility workers reported that musculoskeletal symptoms had impacted their ability to perform their job, housework and/or hobbies in the preceding 12 months. Early access to rehabilitation services is essential. However, many workers report barriers to disclosing MSDs; therefore, workplace rehabilitation services may need to be broadened to account for these barriers.

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.

Bichectomy Surgery and EMG Masticatory Muscles Function in Adult Women: A Longitudinal Study

AIM

This longitudinal study aimed to evaluate the electromyographic activity of the masseter and temporal muscles in adult women who underwent buccal fat removal.

MATERIALS AND METHODS

The sample consisted of 20 healthy adult women with no temporomandibular dysfunction and normal occlusion, who were assessed before, 30, and 60 days after the surgery. The electromyographic signal of the masseter and temporal muscles was captured through mandibular tasks including rest, protrusion, right and left laterality, and maximum voluntary contraction with and without parafilm. The results obtained were tabulated and the Shapiro-Wilk normality test was performed, which indicated a normal distribution. Statistical analysis was performed using the repeated measures test (p < 0.05).

RESULTS

Significant differences were observed between time periods in maximum voluntary contraction for the left masseter muscle (p = 0.006) and in maximum voluntary contraction with parafilm for the right temporal (p = 0.03) and left temporal (p = 0.03) muscles.

CONCLUSION

Bichectomy surgery did not modify the electromyographic activity of the masseter and temporal muscles during the rest task but may have influenced variations in the electromyographic signal during different mandibular tasks after 60 days of surgery, suggesting compensatory adaptations and functional recovery.

CLINICAL SIGNIFICANCE

Understanding the impact of buccal fat removal surgery on the stomatognathic system function provides insights into postoperative functional recovery and potential compensatory adaptations, guiding clinical management and rehabilitation strategies for patients undergoing such procedures. How to cite this article: Cardoso AHDLS, Palinkas M, Bettiol NB, et al. Bichectomy Surgery and EMG Masticatory Muscles Function in Adult Women: A Longitudinal Study. J Contemp Dent Pract 2024;25(3):207-212.

Acute effect of breathing exercises on muscle tension and executive function under psychological stress

Introduction

Intensive and long-lasting office work is a common cause of muscular and mental disorders due to workplace stressors. Mindful and slow breathing exercises decrease psychological stress and improve mental health, whereas fast breathing increases neuronal excitability. This study aimed to explore the influence of 5 min of mindful breathing (MINDFUL), slow breathing (SLOW), fast breathing (FAST), and listening to music (MUSIC) on muscle tension and executive function during an intensive psychological task.

Methods

Forty-eight participants (24 men and 24 women) were enrolled. Muscle tension was recorded using surface electromyography, and executive function was assessed using the Stroop Color and Word Test (Stroop Test). The respiration rate (RR), oxygen saturation (SpO₂), end-tidal carbon dioxide (EtCO₂), and the subjects' preferred method were also recorded. During the experiment, participants performed a one-time baseline test (watching a neutral video for 5 min) and then completed 5 min of MUSIC, MINDFUL, SLOW, and FAST in a random sequence. The Stroop Test was performed after each intervention, including the baseline test, and was followed by a 5 min rest before performing the next intervention.

Results

None of the methods significantly influenced muscular activity and performance of the Stroop Test in both men and women, based on the average 5 min values. However, at the fifth minute, men's accuracy rate in the Stroop Test was significantly higher after SLOW than after MUSIC and FAST, and the reaction time after the SLOW was the shortest. SpO₂ was significantly higher during SLOW than during MUSIC, and RR was relatively lower after SLOW than after MUSIC. Most men preferred SLOW, and most women preferred MUSIC, whereas FAST was the most unfavorable method for both men and women.

Conclusion

Brief breathing exercises did not substantially affect muscle tension under psychological stress. SLOW demonstrated greater potential for sustaining executive function in men, possibly via its superior respiration efficiency on SpO₂ and inhibition of RR.

Use of wearable physiological sensors to predict cognitive workload in a visuospatial learning task

BACKGROUND

Increased cognitive workload, sometimes known as mental strain or mental effort, has been associated with reduced performance.

OBJECTIVE

The use of physiological monitoring was investigated to predict cognitive workload and performance.

METHODS

Twenty-one participants completed a 10-minute seated rest, a visuospatial learning task modeled after crane operation, and the Stroop test, an assessment that measures cognitive interference. Heart rate, heart rate variability, electrodermal activity, skin temperature, and electromyographic activity were collected.

RESULTS

It was found that participants' ability to learn the simulated crane operation task was inversely correlated with self-reported frustration. Significant changes were also found in physiological metrics in the simulation with respect to rest, including an increase in heart rate, electrodermal activity, and trapezius muscle activity; heart rate and muscle activity were also correlated with simulation performance. The relationship between physiological measures and self-reported workload was modeled and it was found that muscle activity and high frequency power, a measure of heart rate variability, were significantly associated with the workload reported.

CONCLUSIONS

The findings support the use of physiological monitoring to inform real time decision making (e.g., identifying individuals at risk of injury) or training decisions (e.g., by identifying individuals that may benefit from additional training even when no errors are observed).

REAC Neuromodulation Treatments in Depression, Anxiety and Stress. A Comparative Retrospective Study

Introduction

The purpose of this retrospective study was to compare the effects of two different modalities of administration of the neuro psycho physical optimization (NPPO) neuromodulation treatment, applied with radio electric asymmetric conveyer (REAC) biotechnology devices. Both the modalities are aimed at improving the strategies to deal with and optimize the allostatic response to environmental stressors and exposome. This allows to reduce the dysfunctional adaptive behavior patterns, which underlie many neuropsychological symptoms and pathologies, and to improve the symptoms of depression, anxiety and stress.

Materials and Methods

From a population of subjects experiencing at least two of the three symptoms depression, anxiety and stress, the selection of pre and post-treatment Depression, Anxiety, Stress 21 items scale (DASS 21) data was made proceeding with a reverse chronological recruitment mechanism, until reaching 150 subjects for each of the 2 groups. The first group was treated with the neuro psycho physical optimization treatment (NPPO), which is the punctiform modality of administration on the auricle pavilion, and the second group was treated with the neuro psycho physical optimization treatment, which is the area modality of administration applied by the planar probe on the cervicobrachial area (NPPO-CB).

Results

The Wilcoxon signs test confirmed the differences in scores in pre and post-treatment DASS-21. The comparison between the two groups data and the comparison across groups data showed that NPPO and NPPO-CB have the same efficacy in reducing the symptoms of depression, anxiety and stress, after a single treatment cycle. Statistical significance was set at p <0.05.

Discussion

This is the first efficacy descriptive comparison between the two different modalities of administration of the NPPO treatment, as different options for the same clinical indication.

REAC Cervicobrachial Neuromodulation Treatment of Depression, Anxiety, and Stress During the COVID-19 Pandemic

Introduction

In addition to the effects of coronavirus infection, the Covid-19 pandemic has induced widespread psychosocial distress, which has triggered the onset of anxious and depressive states, reactive to the socio-relational and economic situation induced by the pandemic. Some of our participants showed depressive and anxious attitudes even in the absence of real pictures of depression and anxiety. This phenomenon, combined with mechanisms of emulation and conditioning, can trigger a vicious cycle within interpersonal relationships and promote the administration of unnecessary treatments. Various approaches have been proposed to help populations suffering from psychosocial problems induced by the Covid-19 pandemic, but there is an objective difficulty in treating a large population.

Methods

To contain and reduce this widespread psychosocial unease, in this study we used two radio electric asymmetric conveyer (REAC) technology neuromodulation treatments, neuro postural optimization (NPO) and neuropsychophysical optimization-cervicobrachial (NPPO-CB), aimed at optimizing an individual's response to the effects of environmental stressors. These treatments are quick and easy to administer; therefore, they can be administered to a large cohort of participants in a short time. To evaluate the effects of the REAC NPO and NPPO-CB treatments, the DASS-21 psychometric test was used because it has already been used to test depression, anxiety, and stress during the Covid-19 pandemic.

Results

The results of the study confirm the usefulness of REAC NPO and NPPO-CB treatments in helping participants to have better coping strategies for the environmental pressures and reduce the neuropsychological and behavioral effects induced by the Covid-19 pandemic.

Discussion

The results obtained in this study are consistent with previous clinical studies confirming the usefulness of the treatments to face neuropsychological and behavioral effects induced by exposome pressure.

Shoulder Muscular Fatigue From Static Posture Concurrently Reduces Cognitive Attentional Resources

OBJECTIVE

The goal of this work is to determine whether muscular fatigue concurrently reduces cognitive attentional resources in technical tasks for healthy adults.

BACKGROUND

Muscular fatigue is common in the workplace but often dissociated with cognitive performance. A corpus of literature demonstrates a link between muscular fatigue and cognitive function, but few investigations demonstrate that the instigation of the former degrades the latter in a way that may affect technical task completion. For example, laparoscopic surgery increases muscular fatigue, which may risk attentional capacity reduction and undermine surgical outcomes.

METHOD

A total of 26 healthy participants completed a dual-task cognitive assessment of attentional resources while concurrently statically fatiguing their shoulder musculature until volitional failure, in a similar loading pattern observed in laparoscopic procedures. Continuous and discrete monitoring task performance was recorded to reflect attentional resources.

RESULTS

Electromyography of the anterior deltoid and descending trapezius, as well as self-assessment surveys indicated fatigue occurrence; continuous tracking error, tracking velocity, and response time significantly increased with muscular fatigue.

CONCLUSION

Muscular fatigue concurrently degrades cognitive attentional resources.

APPLICATION

Complex tasks that rely on muscular and cognitive performance should consider interventions to reduce muscular fatigue to also preserve cognitive performance.

Cognitive stress changes the attributes of the three heads of the triceps brachii during muscle fatigue

INTRODUCTION

Cognitive stress (CS) changes the peripheral attributes of a muscle, but its effect on multi-head muscles has not been investigated. The objective of the current research was to investigate the impact of CS on the three heads of the triceps brachii (TB) muscle.

METHODS

Twenty-five young and healthy university students performed a triceps push-down exercise at 45% one repetition maximum (1RM) with and without CS until task failure, and the rate of fatigue (ROF), endurance time (ET) and number of repetitions (NR) for both exercises were analyzed. In addition, the first and last six repetitions of each exercise were considered non-fatiguing (NF) and fatiguing (Fa), respectively, and the root mean square (RMS), mean power frequency (MPF) and median frequency (MDF) for each exercise repetition were evaluated.

RESULTS

The lateral and long head showed significant differences (P<0.05) in the ROF between the two exercises, and all the heads showed significant (P<0.05) differences in the RMS between the two exercises under NF conditions. Only the long head showed a significant difference (P<0.05) in the MPF and MDF between the two exercises. CS increases the ET (24.74%) and NR (27%) of the exercise. The three heads showed significant differences (P<0.05) in the RMS, MPF and MDF under all exercise conditions.

CONCLUSION

A lower ROF was obtained with CS. In addition, the RMS was found to be better approximator of CS, whereas MPF and MDF were more resistant to the effect of CS. The results showed that the three heads worked independently under all conditions, and the non-synergist and synergist head pairs showed similar behavior under Fa conditions. The findings from this study provide additional insights regarding the functioning of each TB head.

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.

Distress and worry as mediators in the relationship between psychosocial risks and upper body musculoskeletal complaints in highly automated manufacturing

As a result of changes in manufacturing including an upward trend in automation and the advent of the fourth industrial revolution, the requirement for supervisory monitoring and consequently, cognitive demand has increased in automated manufacturing. The incidence of musculoskeletal disorders has also increased in the manufacturing sector. A model was developed based on survey data to test if distress and worry mediate the relationship between psychosocial factors (job control, cognitive demand, social isolation and skill discretion), stress states and symptoms of upper body musculoskeletal disorders in highly automated manufacturing companies (n = 235). These constructs facilitated the development of a statistically significant model (RMSEA 0.057, TLI 0.924, CFI 0.935). Cognitive demand was shown to be related to higher distress in employees, and distress to a higher incidence of self-reported shoulder and lower back symptoms. The mediation model incorporating stress states (distress, worry) as mediators is a novel approach in linking psychosocial risks to musculoskeletal disorders. Practitioners' Summary With little requirement for physical work in many modern automated manufacturing workplaces, there is often minimal management focus on Work-Related Musculoskeletal Disorders (WRMSDs) as important occupational health problems. Our model provides evidence that psychosocial factors are important risk factors in symptoms of WRMSD and should be managed.

Fighter pilots' heart rate, heart rate variation and performance during instrument approaches

Fighter pilots' heart rate (HR), heart rate variation (HRV) and performance during instrument approaches were examined. The subjects were required to fly instrument approaches in a high-fidelity simulator under various levels of task demand. The task demand was manipulated by increasing the load on the subjects by reducing the range at which they commenced the approach. HR and the time domain components of HRV were used as measures of pilot mental workload (PMWL). The findings of this study indicate that HR and HRV are sensitive to varying task demands. HR and HRV were able to distinguish the level of PMWL after which the subjects were no longer able to cope with the increasing task demands and their instrument landing system performance fell to a sub-standard level. The major finding was the HR/HRV's ability to differentiate the sub-standard performance approaches from the high-performance approaches. Practitioner Summary: This paper examined if HR and HRV were sensitive to varying task demands in a fighter aviation environment and if these measures were related to variations in pilot's performance.

Respiratory Changes in Response to Cognitive Load: A Systematic Review

When people focus attention or carry out a demanding task, their breathing changes. But which parameters of respiration vary exactly and can respiration reliably be used as an index of cognitive load? These questions are addressed in the present systematic review of empirical studies investigating respiratory behavior in response to cognitive load. Most reviewed studies were restricted to time and volume parameters while less established, yet meaningful parameters such as respiratory variability have rarely been investigated. The available results show that respiratory behavior generally reflects cognitive processing and that distinct parameters differ in sensitivity: While mentally demanding episodes are clearly marked by faster breathing and higher minute ventilation, respiratory amplitude appears to remain rather stable. The present findings further indicate that total variability in respiratory rate is not systematically affected by cognitive load whereas the correlated fraction decreases. In addition, we found that cognitive load may lead to overbreathing as indicated by decreased end-tidal CO₂ but is also accompanied by elevated oxygen consumption and CO₂ release. However, additional research is needed to validate the findings on respiratory variability and gas exchange measures. We conclude by outlining recommendations for future research to increase the current understanding of respiration under cognitive load.

Effect of exams period on prevalence of Myofascial Trigger points and head posture in undergraduate students: Repeated measurements study

BACKGROUND

Myofascial Trigger points (MTrPs) may be caused or aggravated by many factors, such as mental stress associated with exams and impaired posture.

AIM

To compare the prevalence and sensitivity of MTrPs, and forward head position (FHP) during exam period vs. mid-semester among physical therapy students.

METHODS

39 physical therapy students were palpated for MTrPs in neck and shoulder muscles and were photographed laterally for FHP measurement during the academic semester and during the academic examination period.

RESULTS

The subjects showed higher prevalence of active MTrPs in the right Trapezius and Levator Scapula muscles, and higher prevalence of latent MTrPs in the left Sternocleidomastoideus and Levator Scapula muscles during exams, as well as a higher rate of tenderness in suboccipital musculature.

CONCLUSIONS

Physical therapy students show greater prevalence of MTrPs during exams. The authors recommend implementing preventative programs towards the examination period.

Developmental nicotine exposure alters cholinergic control of respiratory frequency in neonatal rats

Prenatal nicotine exposure with continued exposure through breast milk over the first week of life (developmental nicotine exposure, DNE) alters the development of brainstem circuits that control breathing. Here, we test the hypothesis that DNE alters the respiratory motor response to endogenous and exogenous acetylcholine (ACh) in neonatal rats. We used the brainstem-spinal cord preparation in the split-bath configuration, and applied drugs to the brainstem compartment while measuring the burst frequency and amplitude of the fourth cervical ventral nerve roots (C4VR), which contain the axons of phrenic motoneurons. We applied ACh alone; the nicotinic acetylcholine receptor (nAChR) antagonist curare, either alone or in the presence of ACh; and the muscarinic acetylcholine receptor (mAChR) antagonist atropine, either alone or in the presence of ACh. The main findings include: (1) atropine reduced frequency similarly in controls and DNE animals, while curare caused modest slowing in controls but no consistent change in DNE animals; (2) DNE greatly attenuated the increase in C4VR frequency mediated by exogenous ACh; (3) stimulation of nAChRs with ACh in the presence of atropine increased frequency markedly in controls, but not DNE animals; (4) stimulation of mAChRs with ACh in the presence of curare caused a modest increase in frequency, with no treatment group differences. DNE blunts the response of the respiratory central pattern generator to exogenous ACh, consistent with reduced availability of functionally competent nAChRs; DNE did not alter the muscarinic control of respiratory motor output. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 76: 1138-1149, 2016.