Portable neuroimaging differentiates novices from those with experience for the Fundamentals of Laparoscopic Surgery (FLS) suturing with intracorporeal knot tying task.

BACKGROUND: The goal of this study was to compare the brain activation patterns of experienced and novice individuals when performing the Fundamentals of Laparoscopic Surgery (FLS) suture with intracorporeal knot tying task, which requires bimanual motor control. METHODS: Twelve experienced and fourteen novice participants completed this cross-sectional observational study. Participants performed three repetitions of the FLS suture with intracorporeal knot tying task in a standard box trainer. Functional near infrared spectroscopy (fNIRS) data was recorded using an optode montage that covered the prefrontal and sensorimotor brain areas throughout the task. Data processing was conducted using the HOMER3 and AtlasViewer toolboxes to determine the oxy-hemoglobin (HbO) and deoxyhemoglobin (HbR) concentrations. The hemodynamic response function based on HbO changes during the task relative to the resting state was averaged for each repetition and by participant. Group-level differences were evaluated using a general linear model of the HbO changes with significance set at p < 0.05. RESULTS: The average performance score for the experienced group was significantly higher than the novice group (p < 0.01). There were significant cortical activations (p < 0.05) in the prefrontal and sensorimotor areas for the experienced and novice groups. Areas of statistically significant differences in activation included the right dorsolateral prefrontal cortex (PFC), the right precentral gyrus, and the right postcentral gyrus. CONCLUSIONS: Portable neuroimaging allowed for the differentiation of brain regions activated by experienced and novice participants for a complex surgical motor task. This information can be used to support the objective evaluation of expertise during surgical skills training and assessment.

The relationship between ratings of perceived exertion (RPE) and relative strength for a fatiguing dynamic upper extremity task: A consideration of multiple cycles and conditions.

The goal of this study was to evaluate the relationship between ratings of perceived exertion (RPE) and relative strength with respect to baseline for a fatiguing free dynamic task targeting the upper extremity, namely simulated order picking, and determine whether the relationship remains the same for different conditions (i.e., pace and weight) and with fatigue. Fourteen participants (seven males, seven females) performed four sessions that included two 45-min work periods separated by 15 min of rest. The work periods involved picking weighted bottles from shoulder height and packaging them at waist height for four combinations of bottle mass and picking rate: 2.5 kg-15 bottles per minute (bpm), 2.5 kg-10 bpm, 2.5 kg-5 bpm, and 1.5 kg-15 bpm. Participants reported their RPEs every 5 min and performed a maximum isometric shoulder flexion exertion every 9 min. Pearson product-moment correlation was used to evaluate the linear relationship between RPE and relative strength for each subject and work period. Then, the effects of condition and work period on the average relationship were assessed using a repeated-measures analysis of variance (ANOVA). For the first 45-min period, there were no significantly different correlations between RPE and relative strength across conditions (average r = -0.62 (standard deviation = 0.38); p = 0.57). There was a significant decrease in average correlation for the second work period (r = -0.39 (0.53)). These results suggest that individual subjective responses consistently increase while relative strength declines when starting from a non-fatigued state. However, correlations are weaker when re-engaging in work following incomplete recovery. Thus, starting fatigue levels should be accounted for when considering the expected relationship between RPE and relative strength.

Influence of hierarchy on risk communication during robot-assisted surgery: a preliminary study.

INTRODUCTION: A hierarchical structure is where all individuals are organized according to importance and are subordinate to a single person. In the operating room (OR), this structure may negatively impact the quality of communication and jeopardize patient safety. We examined how the surgical team's hierarchical relationships affect the frequency and timing of risk communication, and their influence on situational awareness (SA) in the OR. METHODS: Overhead cameras and lapel microphones were used to record the OR environment. Recordings and transcriptions of 10 robot-assisted prostatectomies were examined for risk utterances among team members. Utterances were classified by sender-recipient exchange, timing (determined by phrasing to be proactive or reactive to an error/negative event), and the Oxford Non-Technical Skills (NOTECHS) SA score. Surgeon's and trainee surgeon's utterances were classified by their on-console status. Chi-square tests were used to determine associations between dependent factors, and ANOVAs were used to evaluate the effect of hierarchy and timing on NOTECHS score. RESULTS: Of 4,583 examined utterances, 329 (7%) were risk-related. There was no significant difference in utterance frequency based on hierarchical status of sender and recipient (p = 0.16). Utterances made by the surgeon or trainee surgeon had higher NOTECHS scores when off versus on the console (scores: 1.8 vs 2.4, p < 0.01). These utterances were more reactive on the console (32%) and proactive off the console (28%). Proactive utterances had higher NOTECHS scores than reactive utterances (scores: 2.5 vs 1.8, p < 0.01). CONCLUSION: The surgical hierarchy significantly impacted the frequency of risk communication within the OR. Timing and on-console status further influenced the efficacy of risk communication.

Adjustments in Shoulder and Back Kinematics during Repetitive Palletizing Tasks.

Repetitive task performance is a leading cause of musculoskeletal injuries among order-picking workers in warehouses. The repetition of lifting tasks increases the risk of back and shoulder injuries among these workers. While lifting in this industry is composed of loaded and unloaded picking and placing, the existing literature does not address the separate analysis of the biomechanics of the back and shoulder for these events. To that end, we investigated the kinematics of the back and shoulder movements of nine healthy male participants who performed three sessions of a simulated de/palletization task. Their back and shoulder kinematics were sensed using an optical motion capture system to determine the back inclination and shoulder flexion. Comparison of the kinematics between the first and last sessions indicated statistically significant changes in the timings, angles, coordination between the back and shoulder, and moments around the shoulder (p<0.05). The majority of the significant changes were observed during the loaded events, which confirms the importance of the separation of these events for biomechanical analysis. This finding suggests that focusing worker evaluation on the loaded periods can provide important information to detect kinematic changes that may affect musculoskeletal injury risk.

Teaching surgery novices and trainees advanced laparoscopic suturing: a trial and tribulations.

INTRODUCTION: The benefits of minimally invasive surgery are numerous; however, considerable variability exists in its application and there is a lack of standardized training for important advanced skills. Our goal was to determine whether participation in an advanced laparoscopic curriculum (ALC) results in improved laparoscopic suturing skills. METHODS AND PROCEDURES: Study design was a prospective, randomized controlled trial. Surgery novices and trainees underwent baseline FLS training and were pre-tested on bench models. Participants were stratified by pre-test score and randomized to undergo either further FLS training (control group) or ALC training (intervention group). All were post-tested on the same bench model. Tests for differences between post-test scores of cohorts were performed using least squared means. Multivariable regression identified predictors of post-test score, and Wilcoxon rank sum test assessed for differences in confidence improvement in laparoscopic suturing ability between groups. RESULTS: Between November 2018 and May 2019, 25 participants completed the study (16 females; 9 males). After adjustment for relevant variables, participants randomized to the ALC group had significantly higher post-test scores than those undergoing FLS training alone (mean score 90.50 versus 82.99, p = 0.001). The only demographic or other variables found to predict post-test score include level of training (p = 0.049) and reported years of video gaming (p = 0.034). There was no difference in confidence improvement between groups. CONCLUSIONS: Training using the ALC as opposed to basic laparoscopic skills training only is associated with superior advanced laparoscopic suturing performance without affecting improvement in reported confidence levels. Performance on advanced laparoscopic suturing tasks may be predicted by lifetime cumulative video gaming history and year of training but does not appear to be associated with other factors previously studied in relation to basic laparoscopic skills, such as surgical career aspiration or musical ability.

Investigation of Heterogeneity Sources for Occupational Task Recognition via Transfer Learning.

Human activity recognition has been extensively used for the classification of occupational tasks. Existing activity recognition approaches perform well when training and testing data follow an identical distribution. However, in the real world, this condition may be violated due to existing heterogeneities among training and testing data, which results in degradation of classification performance. This study aims to investigate the impact of four heterogeneity sources, cross-sensor, cross-subject, joint cross-sensor and cross-subject, and cross-scenario heterogeneities, on classification performance. To that end, two experiments called separate task scenario and mixed task scenario were conducted to simulate tasks of electrical line workers under various heterogeneity sources. Furthermore, a support vector machine classifier equipped with domain adaptation was used to classify the tasks and benchmarked against a standard support vector machine baseline. Our results demonstrated that the support vector machine equipped with domain adaptation outperformed the baseline for cross-sensor, joint cross-subject and cross-sensor, and cross-subject cases, while the performance of support vector machine equipped with domain adaptation was not better than that of the baseline for cross-scenario case. Therefore, it is of great importance to investigate the impact of heterogeneity sources on classification performance and if needed, leverage domain adaptation methods to improve the performance.

Interventions to Mitigate Fatigue Induced by Physical Work: A Systematic Review of Research Quality and Levels of Evidence for Intervention Efficacy.

OBJECTIVE: We present a literature review on workplace physical fatigue interventions, focusing on evaluating the methodological quality and strength of evidence. BACKGROUND: Physical fatigue is a recognized workplace problem, with negative effects on performance and health-related complaints. Although many studies have focused on the mechanisms and consequences of fatigue, few have considered the effectiveness of interventions to mitigate fatigue. METHOD: A systematic review of the workplace safety literature for controlled trials of physical fatigue interventions was conducted. Data on intervention type, subject characteristics, targeted tasks and body locations, outcome measures, and study design were extracted. The methodological quality for each study was evaluated using the PEDro scale, and the level of evidence was based on quality, amount, and consistency. RESULTS: Forty-five controlled trials were reviewed, examining 18 interventions. We categorized those interventions into individual-focused (N = 28 studies, nine interventions), workplace-focused (N = 12 studies, five interventions), and multiple interventions (N = 5 studies, four interventions). We identified moderate evidence for interventions related to assistive devices and task variation. There was moderate evidence supporting no fatigue attenuation for the garment change category of interventions. The interventions in the remaining categories had limited to minimal evidence of efficacy. The heterogeneity of the included trials precludes the determination of effect size. CONCLUSION: This review showed a lack of high levels of evidence for the effectiveness of most physical fatigue interventions. APPLICATION: Due to a lack of high levels of evidence for any category of reviewed physical fatigue interventions, further high-quality studies are needed to establish the efficacy of others.

Automated differentiation of benign renal oncocytoma and chromophobe renal cell carcinoma on computed tomography using deep learning.

OBJECTIVES: To develop and evaluate the feasibility of an objective method using artificial intelligence (AI) and image processing in a semi-automated fashion for tumour-to-cortex peak early-phase enhancement ratio (PEER) in order to differentiate CD117(+) oncocytoma from the chromophobe subtype of renal cell carcinoma (ChRCC) using convolutional neural networks (CNNs) on computed tomography imaging. METHODS: The CNN was trained and validated to identify the kidney + tumour areas in images from 192 patients. The tumour type was differentiated through automated measurement of PEER after manual segmentation of tumours. The performance of this diagnostic model was compared with that of manual expert identification and tumour pathology with regard to accuracy, sensitivity and specificity, along with the root-mean-square error (RMSE), for the remaining 20 patients with CD117(+) oncocytoma or ChRCC. RESULTS: The mean ± sd Dice similarity score for segmentation was 0.66 ± 0.14 for the CNN model to identify the kidney + tumour areas. PEER evaluation achieved accuracy of 95% in tumour type classification (100% sensitivity and 89% specificity) compared with the final pathology results (RMSE of 0.15 for PEER ratio). CONCLUSIONS: We have shown that deep learning could help to produce reliable discrimination of CD117(+) benign oncocytoma and malignant ChRCC through PEER measurements obtained by computer vision.

Characterizing the learning curve of a virtual intracorporeal suturing simulator VBLaST-SS©.

BACKGROUND: The virtual basic laparoscopic skill trainer suturing simulator (VBLaST-SS©) was developed to simulate the intracorporeal suturing task in the FLS program. The purpose of this study was to evaluate the training effectiveness and participants' learning curves on the VBLaST-SS© and to assess whether the skills were retained after 2 weeks without training. METHODS: Fourteen medical students participated in the study. Participants were randomly assigned to two training groups (7 per group): VBLaST-SS© or FLS, based on the modality of training. Participants practiced on their assigned system for one session (30 min or up to ten repetitions) a day, 5 days a week for three consecutive weeks. Their baseline, post-test, and retention (after 2 weeks) performance were also analyzed. Participants' performance scores were calculated based on the original FLS scoring system. The cumulative summation (CUSUM) method was used to evaluate learning. Two-way mixed factorial ANOVA was used to compare the effects of group, time point (baseline, post-test, and retention), and their interaction on performance. RESULTS: Six out of seven participants in each group reached the predefined proficiency level after 7 days of training. Participants' performance improved significantly (p < 0.001) after training within their assigned group. The CUSUM learning curve shows that one participant in each group achieved 5% failure rate by the end of the training period. Twelve out of fourteen participants' CUSUM curves showed a negative trend toward achieving the 5% failure rate after further training. CONCLUSION: The VBLaST-SS© is effective in training laparoscopic suturing skill. Participants' performance of intracorporeal suturing was significantly improved after training on both systems and was retained after 2 weeks of no training.

Development and face validation of a virtual camera navigation task trainer.

BACKGROUND: The fundamentals of laparoscopic surgery (FLS) trainer box, which is now established as a standard for evaluating minimally invasive surgical skills, consists of five tasks: peg transfer, pattern cutting, ligation, intra- and extracorporeal suturing. Virtual simulators of these tasks have been developed and validated as part of the Virtual Basic Laparoscopic Skill Trainer (VBLaST) (Arikatla et al. in Int J Med Robot Comput Assist Surg 10:344-355, 2014; Zhang et al. in Surg Endosc 27(10):3603-3615, 2013; Sankaranarayanan et al. in J Laparoendosc Adv Surg Tech 20(2):153-157, 2010; Qi et al. J Biomed Inform 75:48-62, 2017). The virtual task trainers have many advantages including automatic real-time objective scoring, reduced costs, and eliminating human proctors. In this paper, we extend VBLaST by adding two camera navigation system tasks: (a) pattern matching and (b) path tracing. METHODS: A comprehensive camera navigation simulator with two virtual tasks, simplified and cheaper hardware interface (compared to the prior version of VBLaST), graphical user interface, and automated metrics has been designed and developed. Face validity of the system is tested with medical students and residents from the University at Buffalo's medical school. RESULTS: The subjects rated the simulator highly in all aspects including its usefulness in training to center the target and to teach sizing skills. The quality and usefulness of the force feedback scored the lowest at 2.62.

Validation of a virtual intracorporeal suturing simulator.

BACKGROUND: Intracorporeal suturing is one of the most important and difficult procedures in laparoscopic surgery. Practicing on a FLS trainer box is effective but requires large number of consumables, and the scoring is somewhat subjective and not immediate. A virtualbasic laparoscopic skill trainer (VBLaST©) was developed to simulate the five tasks of the FLS Trainer Box. The purpose of this study is to evaluate the face and content validity of the VBLaST suturing simulator (VBLaST-SS©). METHODS: Twenty-five medical students and residents completed an evaluation of the simulator. The participants were asked to perform the standard intracorporeal suturing task on both VBLaST-SS© and the traditional FLS box trainer. The performance scores on each system were calculated based on time (s), deviations to the black dots (mm), and incision gap (mm). The participants were then asked to finish a 13-item questionnaire with ratings from 1 (not realistic/useful) to 5 (very realistic/useful) regarding the face validity of the simulator. A Wilcoxon signed rank test was performed to identify differences in performance on the VBLaST-SS© compared to that of the traditional FLS box trainer. RESULTS: Three questions from the face validity questionnaire were excluded due to lack of response. Ratings to 8 of the remaining 10 questions (80%) averaged above 3.0 out of 5. Average intracorporeal suturing completion time on the VBLaST-SS© was 421 (SD = 168 s) seconds compared to 406 (175 s) seconds on the box trainer (p = 0.620). There was a significant difference between systems for the incision gap (p = 0.048). Deviation in needle insertion from the black dot was smaller for the box trainer than the virtual simulator (1.68 vs. 7.12, p < 0.001). CONCLUSION: Participants showed comparable performance on the VBLaST-SS© and traditional box trainer. Overall, the VBLaST-SS© system showed face validity and has the potential to support training for the suturing skills.

Correction to: Validation of a virtual intracorporeal suturing simulator.

The surname of Sreekanth Arikatla incorrectly appeared as Sreekanth Artikala.

Harnessing smartphone technology and three dimensional printing to create a mobile rehabilitation system, mRehab: assessment of usability and consistency in measurement.

BACKGROUND: Residual sensorimotor deficits are common following stroke. While it has been demonstrated that targeted practice can result in improvements in functional mobility years post stroke, there is little to support rehabilitation across the lifespan. The use of technology in home rehabilitation provides an avenue to better support self-management of recovery across the lifespan. We developed a novel mobile technology, capable of quantifying quality of movement with the purpose of providing feedback to augment rehabilitation and improve functional mobility. This mobile rehabilitation system, mRehab, consists of a smartphone embedded in three dimensional printed items representing functional objects found in the home. mRehab allows individuals with motor deficits to practice activities of daily living (ADLs) and receive feedback on their performance. The aim of this study was to assess the usability and consistency of measurement of the mRehab system. METHODS: To assess usability of the mRehab system, four older adults and four individuals with stroke were recruited to use the system, and complete surveys to discuss their opinions on the user interface of the smartphone app and the design of the 3D printed items. To assess the consistency of measurement by the mRehab system, 12 young adults were recruited and performed mRehab ADLs in three lab sessions within 1 week. Young adults were chosen for their expected high level of consistency in motor performance. RESULTS: Usability ratings from older adults and individuals with stroke led us to modify the design of the 3D printed items and improve the clarity of the mRehab app. The modified mRehab system was assessed for consistency of measurement and six ADLs resulted in coefficient of variation (CV) below 10%. This is a commonly used CV goal for consistency. Two ADLs ranged between 10 and 15% CV. Only two ADLs demonstrated high CV. CONCLUSIONS: mRehab is a client-centered technology designed for home rehabilitation that consistently measures performance. Development of the mRehab system provides a support for individuals working on recovering functional upper limb mobility that they can use across their lifespan.

Variability and interpretation of communication taxonomy during robot-assisted surgery: do we all speak the same language?

OBJECTIVE: To investigate and analyse the different ways surgeons communicate with bedside assistants during robot-assisted surgery (RAS). METHODS: We retrospectively reviewed video and audio recordings of 26 RAS procedures (23 prostatectomies and three cystectomies). Three cameras and eight lapel microphones were used to record the operating theatre environment. We identified five common tasks and categorized them into 'specific', 'non-specific' and 'unclear' categories. We also determined the frequency, time to execute the task, inconveniences and acknowledgements associated with each category. The most efficient category was the one that took the shortest duration to accomplish and was associated with the fewest inconveniences. RESULTS: A total of 1 000 requests were made by three surgeons for six bedside assistants by three surgeons. The five identified tasks were: instrument change; clipping; suction; irrigation; and retraction. For instrument change, non-specific requests were the most frequent compared with the other categories (77% vs 18% vs 5%; P < 0.001). For suction, specific requests were the most frequently used of the three categories (73% vs 27% vs 0%; P < 0.001) and this task was associated with the fewest inconveniences (38% vs 62%; P = 0.01). For clipping, irrigation and retraction, both specific and non-specific requests were similar in terms of their frequency, action time and inconveniences. Comparing complete vs incomplete requests, incomplete requests had significantly shorter median action time (5 vs 8 s; P < 0.001) but did not significantly differ in terms of inconveniences and acknowledgement. CONCLUSION: To our knowledge, this is the first study to provide a detailed analysis of communication during RAS. It lays a foundation for standardized taxonomy to improve communication, surgical efficiency and patient safety.

Barriers to the Adoption of Wearable Sensors in the Workplace: A Survey of Occupational Safety and Health Professionals.

OBJECTIVE: To gather information on the (a) types of wearable sensors, particularly personal activity monitors, currently used by occupational safety and health (OSH) professionals; (b) potential benefits of using such technologies in the workplace; and (c) perceived barriers preventing the widespread adoption of wearable sensors in industry. BACKGROUND: Wearable sensors are increasingly being promoted as a means to improve employee health and well-being, and there is mounting evidence supporting their use as exposure assessment and personal health tools. Despite this, many workplaces have been hesitant to adopt these technologies. METHODS: An electronic survey was emailed to 28,428 registered members of the American Society of Safety Engineers (ASSE) and 1,302 professionals certified by the Board of Certification in Professional Ergonomics (BCPE). RESULTS: A total of 952 valid responses were returned. Over half of respondents described being in favor of using wearable sensors to track OSH-related risk factors and relevant exposure metrics at their respective workplaces. However, barriers including concerns regarding employee privacy/confidentiality of collected data, employee compliance, sensor durability, the cost/benefit ratio of using wearables, and good manufacturing practice requirements were described as challenges precluding adoption. CONCLUSION: The broad adoption of wearable technologies appears to depend largely on the scientific community's ability to successfully address the identified barriers. APPLICATION: Investigators may use the information provided to develop research studies that better address OSH practitioner concerns and help technology developers operationalize wearable sensors to improve employee health and well-being.

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.

A machine learning approach to detect changes in gait parameters following a fatiguing occupational task.

The purpose of this study is to provide a method for classifying non-fatigued vs. fatigued states following manual material handling. A method of template matching pattern recognition for feature extraction ($1 Recognizer) along with the support vector machine model for classification were applied on the kinematics of gait cycles segmented by our stepwise search-based segmentation algorithm. A single inertial measurement unit on the ankle was used, providing a minimally intrusive and inexpensive tool for monitoring. The classifier distinguished between states using distance-based scores from the recogniser and the step duration. The results of fatigue detection showed an accuracy of 90% across data from 20 recruited subjects. This method utilises the minimum amount of data and features from only one low-cost sensor to reliably classify the state of fatigue induced by a realistic manufacturing task using a simple machine learning algorithm that can be extended to real-time fatigue monitoring as a future technology to be employed in the manufacturing facilities. Practitioner Summary: We examined the use of a wearable sensor for the detection of fatigue-related changes in gait based on a simulated manual material handling task. Classification based on foot acceleration and position trajectories resulted in 90% accuracy. This method provides a practical framework for predicting realistic levels of fatigue.

Central and peripheral fatigue development in the shoulder muscle with obesity during an isometric endurance task.

BACKGROUND: Fatigue increases the likelihood of developing work-related musculoskeletal disorders and injury. Due to the physiological and neuromuscular changes that accompany obesity, it may alter the fatigue development mechanism and exacerbate injury risk. The upper extremities have the highest incidence rates for work-related musculoskeletal disorders. Therefore, the goals of this study were to investigate the effect of obesity on central vs. peripheral fatigue as well as on the physical signs of fatigue on the middle deltoid muscle. METHODS: A measure of central activation ratio was used to quantify central fatigue by considering the increment in the torque output by superimposed twitch relative to its corresponding maximum voluntary contraction. For this purpose, electrical stimulation was delivered at the middle deltoid muscles of 22 non-obese (18 < body mass index (BMI) < 25 kg/m2) and 17 obese (30 < BMI < 40 kg/m2) individuals aged 18-32 years old. Participants completed superimposed maximum voluntary isometric contractions of shoulder abduction before and after a sustained isometric fatiguing task at either 30 or 60% of the muscle capacity. Differences in endurance time, torque fluctuation, torque loss, and muscle activity measured by an electromyography sensor were also investigated. RESULTS: A greater reduction of voluntary activation of motor units (p = 0.001) with fatigue was observed for individuals who are obese. Contrary to the effect of obesity on central fatigue, a trend toward reduced peripheral fatigue (p = 0.06) was observed for the obese group compared to the non-obese group. On average, a 14% higher rate of torque loss per second was observed among individuals with obesity in comparison to non-obese participants. CONCLUSIONS: The observed greater contribution of central fatigue during the sustained endurance tasks suggests that among young healthy obese individuals, the faster fatigue development with obesity, commonly reported in the literature, is most likely due to the central elements rather than the peripheral factors. This finding has implications for fatigue prevention programs during sustained exertions and can help to develop training, work, and rest schedules considering obesity.

Relationship Between BMI and Fatigability Is Task Dependent.

OBJECTIVE: The objective of the current study was to determine the effect of body mass index (BMI) on fatigability of three different muscle groups at four different work intensities. METHODS: Forty-nine normal-weight, 50 overweight, and 43 obese adults (32.1 ± 9.2 years; 50% males) performed fatiguing handgrip, shoulder flexion, and trunk extension exertions at 20%, 40%, 60%, and 80% of the associated maximum voluntary contractions. RESULTS: Obese adults demonstrated 22% to 30% shorter endurance times than normal-weight adults, but this was only observed at lower intensities and with larger and more postural muscles of the shoulder and low back. Strength and fatigue-related strength loss remained comparable across BMI groups in both males and females in these task-specific conditions. Obesity was associated with faster progression in perception of effort at low-intensity shoulder and trunk exertions. While males were stronger than females across all muscle groups, females exhibited greater shoulder fatigue resistance than males at lower intensity levels. CONCLUSION: Findings indicate that the relationship between obesity and fatigability is task dependent. APPLICATION: These findings provide initial evidence on the impact of obesity on worker capacity. Future work that extends the current investigation to include more occupationally relevant scenarios are needed to facilitate occupational task (re)design and assessment practices, such that altered work capacities of two-thirds of the working population are accommodated.