Exertion-Dependent Effects of Physical and Mental Workload on Physiological Outcomes and Task Performance

Protocol for a scoping review on 'surgical sabermetrics:' technology-enhanced measurement of operative non-technical skills

INTRODUCTION

Surgeons need high fidelity, high quality, objective, non-judgemental and quantitative feedback to measure their performance in order to optimise their performance and improve patient safety. This can be provided through surgical sabermetrics, defined as 'advanced analytics of digitally recorded surgical training and operative procedures to enhance insight, support professional development and optimise clinical and safety outcomes'. The aim of this scoping review is to investigate the assessment of surgeon's non-technical skills using sabermetrics principles, focusing on digital, automated measurements that do not require a human observer.

METHODS AND ANALYSIS

To investigate the current methods of digital, automated measurements of surgeons' non-technical skills, a systematic scoping review will be conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews guidelines, using databases from medicine and other fields. Covidence software is used for screening of potential studies. A data extraction tool will be developed specifically for this study to evaluate the methods of measurement. Quality assurance will be assessed using Quality Assessment Tool for Diverse Designs. Multiple reviewers will be responsible for screening of studies and data extraction.

ETHICS AND DISSEMINATION

This is a review study, not using primary data, and therefore, ethical approval is not required. A range of methods will be employed for dissemination of the results of this study, including publication in journals and conference presentations.

Health-related consequences of the type and utilization rates of electronic devices by college students

Background

College students are leading an evolution of device use both in the type of device and the frequency of use. They have transitioned from desktop stations to laptops, tablets, and especially smartphones and use them throughout the day and into the night.

Methods

Using a 35-min online survey, we sought to understand how technology daily usage patterns, device types, and postures affect pain and discomfort to understand how knowledge of that pain might help students avoid it. Data were analyzed from 515 students (69.5% male) who completed an internet-delivered survey (81.3% response rate).

Results

Participants ranked smartphones as their most frequently used technology (64.0%), followed by laptops and tablets (both 53.2%), and desktop computers (46.4%). Time spent using smartphones averaged over 4.4 h per day. When using their devices, students were more likely to adopt non-traditional workplace postures as they used these devices primarily on the couch or at a chair with no desk.

Conclusion

Recent trends in wireless academic access points along with the portability of small handheld devices, have made smartphones the most common link to educational materials despite having the least favorable control and display scenario from an ergonomic perspective. Further, the potential impact of transitions in work environments due to COVID-19 may further exacerbate ergonomic issues among millions highlighting the need for such work to be carried out.

Methodological Approaches and Recommendations for Functional Near-Infrared Spectroscopy Applications in HF/E Research

OBJECTIVE

The objective of this study was to systematically document current methods and protocols employed when using functional near-infrared spectroscopy (fNIRS) techniques in human factors and ergonomics (HF/E) research and generate recommendations for conducting and reporting fNIRS findings in HF/E applications.

METHOD

A total of 1,687 articles were identified through Ovid-MEDLINE, PubMed, Web of Science, and Scopus databases, of which 37 articles were included in the review based on review inclusion/exclusion criteria.

RESULTS

A majority of the HF/E fNIRS investigations were found in transportation, both ground and aviation, and in assessing cognitive (e.g., workload, working memory) over physical constructs. There were large variations pertaining to data cleaning, processing, and analysis approaches across the studies that warrant standardization of methodological approaches. The review identified major challenges in transparency and reporting of important fNIRS data collection and analyses specifications that diminishes study replicability, introduces potential biases, and increases likelihood of inaccurate results. As such, results reported in existing fNIRS studies need to be cautiously approached.

CONCLUSION

To improve the quality of fNIRS investigations and/or to facilitate its adoption and integration in different HF/E applications, such as occupational ergonomics and rehabilitation, recommendations for fNIRS data collection, processing, analysis, and reporting are provided.

Task and sex differences in muscle oxygenation during handgrip fatigue development

The purpose of this study was to examine task and sex differences in forearm muscle oxygenation, measured using near infrared spectroscopy, during sustained submaximal handgrip exercises. Forty-eight adults (50% males) performed fatiguing handgrip exercises at 20, 40, 60 and 80% of their maximum handgrip strength. While males and females exhibited similar levels of relative fatigability, forearm oxygenation was found to be task (i.e. contraction intensity and phase of fatigue development) and sex dependent. Higher contraction intensities were associated with greater desaturation over time. Compared to females, males exhibited greater desaturation as fatigue progressed and this was augmented at higher contraction intensities. These may be likely affected by sex differences in muscle mass, morphology and strength differences during exercises at relative intensities. Future work that explores sex differences in muscle oxygenation during absolute force intensities are needed, which may have implications for muscle fatigue development and potential fatigue mitigation strategies. Practitioner Summary: Muscle oxygenation impacts fatigue development that can in turn affect worker health and productivity. Males exhibit greater forearm desaturation than females at higher relative work intensities, despite similar fatigue levels. Females may be predisposed to greater muscle delivery and oxygenation challenges that can increase their fatigability during work at absolute load levels.

Task-relevant cognitive and motor functions are prioritized during prolonged speed-accuracy motor task performance

This study aimed to explore the effect of prolonged speed-accuracy motor task on the indicators of psychological, cognitive, psychomotor and motor function. Ten young men aged 21.1 ± 1.0 years performed a fast- and accurate-reaching movement task and a control task. Both tasks were performed for 2 h. Despite decreased motivation, and increased perception of effort as well as subjective feeling of fatigue, speed-accuracy motor task performance improved during the whole period of task execution. After the motor task, the increased working memory function and prefrontal cortex oxygenation at rest and during conflict detection, and the decreased efficiency of incorrect response inhibition and visuomotor tracking were observed. The speed-accuracy motor task increased the amplitude of motor-evoked potentials, while grip strength was not affected. These findings demonstrate that to sustain the performance of 2-h speed-accuracy task under conditions of self-reported fatigue, task-relevant functions are maintained or even improved, whereas less critical functions are impaired.

Age-specific neural strategies to maintain motor performance after an acute social stress bout

Stress due to cognitive demands and fatigue have shown to impair motor performance in older adults; however, the effect of social stress and its influence on prefrontal cortex (PFC) functioning in older adults during upper extremity motor performance tasks is not known. The present study explored the after-effects of an acute social stress bout on neural strategies, measured using PFC and hand/arm muscle activation, and adopted by younger and older adults to maintain handgrip force control. Nine older [74.1 (6.5) years; three men, six women] and ten younger [24.2 (5.0) years, four men, six women] adults performed handgrip force control trials at 30% maximum voluntary contractions before and after the Trier Social Stress Test (TSST). PFC activity was measured using functional near infrared spectroscopy and muscle activity from the flexor and extensor carpi radialis (FCR/ECR) was measured using electromyography. In general, aging was associated with decreased force steadiness and force complexity with a concomitant increase in bilateral PFC activity. While motor performance remained comparable before and after the TSST stress session in both age groups, the associated neural strategies differed between groups. While the stress condition was associated with lower FCR and ECR activity in younger adults despite no change in the PFC activation, stress was associated with increases in FCR activity in older adults. This stress-related compensatory neural strategy of increasing hand/arm muscle activation, potentially via the additional recruitment of the stress-motor neural circuitry, may have played a role in maintaining motor performance in older adults.

The effect of cognitive fatigue on prefrontal cortex correlates of neuromuscular fatigue in older women

BACKGROUND

As the population of adults aged 65 and above is rapidly growing, it is crucial to identify physical and cognitive limitations pertaining to daily living. Cognitive fatigue has shown to adversely impact neuromuscular function in younger adults, however its impact on neuromuscular fatigue, and associated brain function changes, in older adults is not well understood. The aim of the study was to examine the impact of cognitive fatigue on neuromuscular fatigue and associated prefrontal cortex (PFC) activation patterns in older women.

METHODS

Eleven older (75.82 (7.4) years) females attended two sessions and performed intermittent handgrip exercises at 30 % maximum voluntary contraction (MVC) until voluntary exhaustion after a 60-min control (watching documentary) and 60-min cognitive fatigue (performing Stroop Color Word and 1-Back tests) condition. Dependent measures included endurance time, strength loss, PFC activity (measured using fNIRS), force fluctuations, muscle activity, cardiovascular responses, and perceived discomfort.

RESULTS

Participants perceived greater cognitive fatigue after the 60-min cognitive fatigue condition when compared to the control condition. While neuromuscular fatigue outcomes (i.e., endurance time, strength loss, perceived discomfort), force fluctuations, and muscle activity were similar across both the control and cognitive fatigue conditions, greater decrements in PFC activity during neuromuscular fatigue development after the cognitive fatigue condition were observed when compared to the control condition.

CONCLUSION

Despite similar neuromuscular outcomes, cognitive fatigue was associated with blunted PFC activation during the handgrip fatiguing exercise that may be indicative of neural adaptation with aging in an effort to maintain motor performance. Examining the relationship between cognitive fatigue and neuromuscular output by imaging other motor-related brain regions are needed to provide a better understanding of age-related compensatory adaptations to perform daily tasks that involve some levels of cognitive demand and physical exercise, especially when older adults experience them sequentially.

Subjective evaluation of physical and mental workload interactions across different muscle groups

Both physical and mental demands, and their interactions, have been shown to increase biomechanical loading and physiological reactivity as well as impair task performance. Because these interactions have shown to be muscle-dependent, the aim of this study was to determine the sensitivity of the NASA Task Load Index (NASA TLX) and Ratings of Perceived Exertion (RPE) to evaluate physical and mental workload during muscle-specific tasks. Twenty-four participants performed upper extremity and low back exertions at three physical workload levels in the absence and presence of a mental stressor. Outcome measures included RPE and NASA TLX (six sub-scales) ratings. The findings indicate that while both RPEs and NASA TLX ratings were sensitive to muscle-specific changes in physical demand, only an additional mental stressor and its interaction with either physical demand or muscle groups influenced the effort sub-scale and overall workload scores of the NASA TLX. While additional investigations in actual work settings are warranted, the NASA TLX shows promise in evaluating perceived workload that is sensitive not only to physical and mental demands but also sensitive in determining workload for tasks that employ different muscle groups.

Effects of mental fatigue on the development of physical fatigue: a neuroergonomic approach

OBJECTIVE

The present study used a neuroergonomic approach to examine the interaction of mental and physical fatigue by assessing prefrontal cortex activation during submaximal fatiguing handgrip exercises.

BACKGROUND

Mental fatigue is known to influence muscle function and motor performance, but its contribution to the development of voluntary physical fatigue is not well understood.

METHOD

A total of 12 participants performed separate physical (control) and physical and mental fatigue (concurrent) conditions at 30% of their maximal handgrip strength until exhaustion. Functional near infrared spectroscopy was employed to measure prefrontal cortex activation, whereas electromyography and joint steadiness were used simultaneously to quantify muscular effort.

RESULTS

Compared to the control condition, blood oxygenation in the bilateral prefrontal cortex was significantly lower during submaximal fatiguing contractions associated with mental fatigue at exhaustion, despite comparable muscular responses.

CONCLUSION

The findings suggest that interference in the prefrontal cortex may influence motor output during tasks that require both physical and cognitive processing.

APPLICATION

A neuroergonomic approach involving simultaneous monitoring of brain and body functions can provide critical information on fatigue development that may be overlooked during traditional fatigue assessments.

The influence of precision requirements and cognitive challenges on upper extremity joint reaction forces, moments and muscle force estimates during prolonged repetitive lifting

Prolonged repetitive lifting is a whole-body exertion. Despite this, the roles and physical exposures of the upper extremities are frequently neglected. The influence of precision requirements and cognitive distractions on upper extremity responses when lifting was evaluated by quantifying several biomechanical upper extremity quantities. Nine participants completed four 30-min lifting tasks with and without simultaneous cognitive distractions and/or precision placement constraints. Specific metrics evaluated were joint reaction forces and moments (wrist, elbow and shoulder) and modelled shoulder muscle forces (38 defined shoulder muscle mechanical elements). The addition of a precision requirement increased several metrics by up to 43%, while the addition of the cognitive distraction task had minimal influence. Furthermore, several metrics decreased by up to 14% after the first 10 min of lifting, suggesting a temporal change of lifting strategy.

PRACTITIONER SUMMARY

Lifting tasks often include precision placements and cognitive demands. This study shows that precision placement during prolonged repetitive lifting increases upper extremity forces and moments, while the addition of a cognitive task is benign. Furthermore, field assessments of repetitive lifting should include observations longer than 10 min, as adaptive strategies appear to be adopted.

Team workload

Extensive research has examined the effects of workload on individual performance. Despite the increasing prevalence of teams addressing complex tasks with high workload, less attention has focused on workload distributions beyond the individual to the team level, likely due to the inherent complexity of defining and measuring team workload. By drawing upon previous work by Funke et al. (2012), the authors synthesize existing literature detailing individual/team performance and workload theory and empirical findings across research domains. Based on this synthesis, a multilevel, theoretically derived framework of team workload, rooted in the science of individual/team performance in complex, dynamic environments is proposed.

Neural Correlates of Physical and Mental Fatigue

The purpose of this study was to determine the neural and muscular correlates of physical and mental fatigue. Twelve young and healthy participants (balanced by gender) performed three fatiguing conditions: 1) isometric handgrip task (HG) at 30% maximum voluntary contraction (MVC); 2) mental arithmetic (MA); and 3) combined handgrip and mental arithmetic (HG+MA). Prefrontal cortex activation, muscle activity, and task performance measures (force fluctuations and mental performance) were obtained continuously during the fatiguing conditions. Results indicated no significant difference in muscle activity and force fluctuations between the HG and HG+MA condition. Compared to the HG condition, an initial increase in the prefrontal cortex activation was observed during the HG+MA condition, with a subsequent decrease at exhaustion. Cortical activation during the MA condition was significantly lower than the other conditions across the entire duration of the fatiguing trial. Participants performed poorly with mental arithmetic during the HG+MA condition compared to the MA condition. The results suggest that the dynamic changes in the prefrontal cortex during the combined HG+MA condition, compared to the HG or MA condition, occur due to the interaction of physical and mental fatigue, which may have important implications for physical and cognitive performance.