Hybrid office work in women and men: do directly measured physical behaviors differ between days working from home and days working at the office?

OBJECTIVE: We investigated and compared temporal sitting patterns among male and female hybrid office workers when working at the office (WAO), working from home (WFH), and for non-working days (NWD). METHODS: We analyzed data collected in 2020 among 165 hybrid office workers, carrying thigh-worn accelerometers for 938 days in total. Day type (WAO, WFH, or NWD) and time in bed were identified using diaries. Time awake was exhaustively classified as non-sitting time and time sitting in short, moderate, and long bouts. Effects of day type and gender on the 24-h compositions of physical behaviors were analyzed using multilevel linear mixed models. RESULTS: During workdays (both WAO and WFH), workers spent less time in bed and more time sitting, particularly in moderate and long bouts, than during NWD. Time in bed was longer when working from home than when working at the office, and more of the awake time was spent sitting. Differences between WAO and WFH in ratios between short, moderate, and long bouts of sitting were small and inconsistent. Men spent more time sitting than women, and more time in moderate and long sitting bouts relative to short bouts. CONCLUSIONS: When working from home, hybrid office workers sat more during their hours awake compared to when working at the office. Sitting time was larger during working days than during non-working days and was higher in men than in women. These results may contribute to support organizational policies for hybrid work.

Ward-level leadership quality and prospective low-back pain of eldercare workers: do resident handlings mediate the association?

OBJECTIVE: We investigated the extent to which ward-level leadership quality was associated with prospective low-back pain among eldercare workers, and how this association was mediated by observed resident handlings. METHODS: 530 Danish eldercare workers, employed in 121 wards, distributed across 20 nursing homes were evaluated. At baseline, leadership quality was measured using the Copenhagen Psychosocial Questionnaire, and resident handlings [handlings per shift, handlings not using assistive devices, handlings done alone, interruptions to handlings, impediments to handlings] were assessed using observations. Frequency and intensity of low-back pain was assessed monthly during the following year. All variables were averaged for each ward. We used ordinary least squares regressions to examine direct effects of leadership on low-back pain and indirect effects through handlings, using PROCESS-macro for SPSS. RESULTS: After adjustments for low-back pain at baseline, type of ward, staff ratio (i.e., number of workers divided by number of residents) and proportion of devices not in place, leadership quality showed no effect on prospective low-back pain frequency (ß = 0.01 [- 0.05:0.07]) and a small beneficial effect on pain intensity (ß = - 0.02 [- 0.04:0.00]). Resident handlings did not mediate the association between leadership quality and frequency or intensity of low-back pain. CONCLUSIONS: Good leadership quality was associated with a small decrease in prospective low-back pain intensity, but resident handlings did not seem to play a mediating role, although better ward-level leadership quality contributed to fewer workplace-observed resident handlings without assistance. Potentially, organizational factors, such as type of ward and staff ratio, may have a greater influence on handlings and low-back pain than leadership quality per se among eldercare workers.

Sedentary behaviour, physical activity, and sleep among office workers during the COVID-19 pandemic: a comparison of Brazil and Sweden.

BACKGROUND: The COVID-19 pandemic has affected the physical behaviours of office workers worldwide, but studies comparing physical behaviours between countries with similar restrictions policies are rare. This study aimed to document and compare the 24-hour time-use compositions of physical behaviours among Brazilian and Swedish office workers on working and non-working days during the pandemic. METHODS: Physical behaviours were monitored over 7 days using thigh-worn accelerometers in 73 Brazilian and 202 Swedish workers. Daily time-use compositions were exhaustively described in terms of sedentary behaviour (SED) in short (< 30 min) and long (≥30 min) bouts, light physical activity (LPA), moderate-to-vigorous physical activity (MVPA), and time-in-bed. We examined differences between countries using MANOVA on data processed according to compositional data analysis. As Swedish workers had the possibility to do hybrid work, we conducted a set of sensitivity analyses including only data from days when Swedish workers worked from home. RESULTS: During working days, Brazilian office workers spent more time SED in short (294 min) and long (478 min) bouts and less time in LPA (156 min) and MVPA (50 min) than Swedish workers (274, 367, 256 and 85 min, respectively). Time spent in bed was similar in both groups. Similar differences between Brazilians and Swedes were observed on non-working days, while workers were, in general, less sedentary, more active and spent more time-in-bed than during working days. The MANOVA showed that Brazilians and Swedes differed significantly in behaviours during working (p <  0.001, ηp2 = 0.36) and non-working days (p <  0.001, ηp2 = 0.20). Brazilian workers spent significantly more time in SED relative to being active, less time in short relative to long bouts in SED, and more time in LPA relative to MVPA, both during workdays and non-workdays. Sensitivity analyses only on data from days when participants worked from home showed similar results. CONCLUSIONS: During the COVID-19 pandemic Brazilian office workers were more sedentary and less active than Swedish workers, both during working and non-working days. Whether this relates to the perception or interpretation of restrictions being different or to differences present even before the pandemic is not clear, and we encourage further research to resolve this important issue.

Nursing Home, Ward and Worker Level Determinants of Perceived Quantitative Work Demands: A Multi-Level Cross-Sectional Analysis in Eldercare.

INTRODUCTION: Perceived quantitative demands at work have been associated with poor mental and physical health, long-term sickness absence and subsequent early retirement. Identifying modifiable determinants of perceived quantitative demands at different levels of the organization is key to developing effective interventions. The aim of the study was to identify determinants of perceived quantitative demands at work and examine the extent to which they occur at different levels of the eldercare organisation (i.e. the worker, ward and nursing home levels). METHODS: We collected data on 383 eldercare workers in 95 wards at 20 nursing homes in Denmark using workplace observations and questionnaires to workers and their managers. Perceived quantitative work demands were assessed using two items from the Copenhagen Psychosocial Questionnaire, II. We identified contributions to overall variability from the three organisational levels using variance components analysis, and examined associations between determinants at these three levels and quantitative demands. RESULTS: Almost all (90.9%) the variability in perceived quantitative demands occurred between eldercare workers (within wards). Determinants significantly associated with lower quantitative demands were: having a job as a care helper, working fixed evening shifts, being born outside Denmark, having lower influence at work, higher quality of leadership and lower emotional demands. None of the investigated physical factors (e.g. resident handlings, push/pull tasks, step-count) were associated with perceived quantitative demands. CONCLUSION: We found that the variability in perceived quantitative demands occurred primarily between eldercare workers within wards. Our study indicates that psychosocial work environment factors are the strongest modifiable determinants of perceived quantitative demands in eldercare, while organisational factors related to job position, shift, and resident-staff ratio also play a role. Interventions should test if changes in these determinants can reduce perceived quantitative demands at work in eldercare.

Associations between perceived quantitative work demands at different organisational levels and pain and sickness absence in eldercare workers: a multi-level longitudinal analysis.

PURPOSE: Eldercare work is characterised by high quantitative work demands and high occurrence of musculoskeletal pain and sickness absence. Our aim was to investigate the association between quantitative demands aggregated at the different organizational levels of eldercare and low back pain (LBP) and sickness absence due to pain among workers. METHODS: This study was conducted in 527 eldercare workers from 105 wards across 20 nursing homes in Denmark. We collected workers' perceived quantitative demands at baseline and workers' LBP and sickness absence repeatedly over the following year. We aggregated worker-level quantitative demands to the ward and nursing home-levels, and used mixed-effects regression models to investigate the associations between quantitative demands at different organizational levels and LBP and sickness absence over 1 year. RESULTS: Across all models, increased quantitative demands (0-100 scale) at the worker-level was associated with an increased likelihood (OR 1.02) and intensity of LBP (ß = 0.01). We did not identify any associations between quantitative demands at the ward-level and either of our outcomes. Across all models, increased quantitative demands at the nursing home-level was associated with increased days with sickness absence due to pain (ß = 0.03 to 0.06). CONCLUSION: In eldercare, workers' perceived quantitative demands are associated with the presence and intensity of LBP. Further, quantitative demands across the overall nursing home-level are associated with sickness absence due to pain among eldercare workers. These results are of relevance to developing organisational interventions targeting quantitative demands to reduce sickness absence in eldercare.

Serratus anterior sEMG - sensor placement and test position for normalization purposes during maximal and submaximal exertions.

There is great variability regarding serratus anterior sEMG sensor placement and test positions during normalization procedures. We investigated between-trials reliability of serratus anterior sEMG, acquired at two sensor placements and four test positions, during maximal and submaximal isometric contractions. Twenty young healthy women participated. sEMG was captured at the 7th intercostal space and at the xiphoid process level, in the mid-axillary line, during maximal and submaximal isometric contractions, in four test positions. Intraclass Correlation Coefficient (ICC2,1), coefficient of variation and standard error of measurement were calculated. Interactions between sensor placements and test positions were investigated using a two-way repeated-measures ANOVA. All test conditions presented ICC2,1 > 0.8. There was no interaction between sensor placement and test position. Signal obtained from the sensor at 7th intercostal space was more stable between-trials and showed higher amplitude, during maximal and submaximal contractions, at seated positions with shoulder protracted at both 90° or 125° of flexion. We suggest to acquire serratus anterior sEMG at the 7th intercostal space and perform maximal or submaximal isometric contractions for signal normalization with shoulder protracted and flexed, at seated position.

Are resident handlings in eldercare wards associated with musculoskeletal pain and sickness absence among the workers? A prospective study based on onsite observations.

OBJECTIVES: We aimed to identify eldercare wards with different types of resident handling characteristics ('phenotypes') and determine the prospective association between these characteristics and musculoskeletal pain and sickness absence among workers during a one-year follow-up. METHODS: Our study was based on the DOSES cohort, including 467 workers at 103 eldercare wards. At baseline, resident handlings were assessed using onsite observations. Workers' self-reported musculoskeletal pain and sickness absence were assessed during the following year using text messages. Observations of the frequency of handlings per shift, use of assistive devices, assistance from others, and barriers (interruptions and impediments) were estimated for each worker, aggregated at ward level, and entered into a latent profile analysis, identifying ward phenotypes. We then used generalized estimating equations to determine associations between ward phenotypes, musculoskeletal pain and sickness absence. RESULTS: We identified four ward phenotypes: 'turbulent' (many handlings with devices and assistance, many barriers), 'strained' (many handlings without devices or assistance, some barriers), 'unpressured' (few handlings, yet without devices or assistance, few barriers) and 'balanced' (some handlings with devices and assistance, some barriers). Compared to workers in balanced wards, workers in turbulent wards had more days with neck-shoulder and low-back pain (LBP); and those working in strained wards had more days with LBP and higher pain intensities. CONCLUSION: We found that ward phenotypes based on resident handling characteristics were predictive of musculoskeletal pain and sickness absence over one year. This shows that organizational factors related to resident handling are important determinants of musculoskeletal health among eldercare workers.

What Determines Step-Rate at Work? An Investigation of Factors at the Shift, Worker, Ward, and Nursing Home Levels in Eldercare.

OBJECTIVES: Current knowledge on the determinants of step-rate at different organizational levels is limited. Thus, our aim was to identify, in eldercare, at what workplace level differences in step-rate occur and to identify determinants of workers' step-rate at these levels. METHODS: Participants were 420 eldercare workers from 17 nursing homes (126 wards) in Denmark. Accelerometry was used to assess step-rate (steps per hour) of workers over multiple shifts. We assessed various determinants at different levels of the workplace, i.e. at the (i) shift, (ii) worker, (iii) ward, and (iv) nursing home levels. Variance components analysis identified the percentage contribution to total variance in step-rate from each respective level. Multi-level linear regression modelling was used to investigate the association between candidate determinants at each level and step-rate. RESULTS: Differences in eldercare workers' step-rate occurred primarily between shifts (within workers; 44.9%) and between workers (within wards; 49.1%). A higher step-rate was associated with: (i) weekend and evening shifts (versus weekday/day); (ii) job as a care helper (versus care aide) and an increased proportion of time spent on direct care tasks; (iii) working in a somatic ward (versus dementia), an increased resident-staff ratio and permission to take unscheduled breaks; and (iv) lack of elevators. CONCLUSIONS: We found that nearly all variability in step-rate in eldercare work occurs between shifts (within workers) and between workers (within wards). The main determinants of step-rate were related to the type of shift, type of work tasks, staffing ratio, break policy, and availability of elevators.

Working from home during the COVID-19 outbreak in Sweden: effects on 24-h time-use in office workers.

BACKGROUND: The COVID-19 pandemic has triggered national recommendations encouraging people to work from home (WFH), but the possible impact of WFH on physical behaviors is unknown. This study aimed to determine the extent to which the 24-h allocation of time to different physical behaviors changes between days working at the office (WAO) and days WFH in office workers during the pandemic. METHODS: Data were collected on 27 office workers with full-time employment at a Swedish municipal division during the COVID-19 outbreak in May-July 2020. A thigh-worn accelerometer (Axivity) was used to assess physical behavior (sedentary, stand, move) during seven consecutive days. A diary was used to identify periods of work, leisure and sleep. 24-h compositions of sedentary, standing and moving behaviors during work and non-work time were examined using Compositional data analysis (CoDA), and differences between days WAO and days WFH were determined using repeated measures ANOVA. RESULTS: Days WFH were associated with more time spent sleeping relative to awake, and the effect size was large (F = 7.4; p = 0.01; ηp2 = 0.22). The increase (34 min) in sleep time during WFH occurred at the expense of a reduction in work and leisure time by 26 min and 7 min, respectively. Sedentary, standing and moving behaviors did not change markedly during days WFH compared to days WAO. CONCLUSION: Days working from home during the COVID-19 pandemic in Sweden were associated with longer duration of sleep than days working at the office. This behavioral change may be beneficial to health.

Combined Effects of Physical Behavior Compositions and Psychosocial Resources on Perceived Exertion Among Eldercare Workers.

OBJECTIVES: High perceived physical exertion is common in eldercare workers and a strong predictor for impaired health. However, little is known on how physical behaviors at work associate with physical exertion in this group. The aim of this study was to determine the extent to which the composition of physical behaviors at work is associated with perceived physical exertion in nursing home eldercare workers, and the extent to which these associations are modified by psychosocial resources. METHODS: Our population consisted of 399 female eldercare workers from 126 wards in 20 different nursing homes. We evaluated time spent in physical behaviors at work [sitting, standing still, light activities (LAs), and moderate to vigorous activities (MVAs)] using triaxial accelerometers worn, on average, for three working days. We accounted for inherent codependency between the behaviors using compositional data analysis. We used multilevel linear mixed regression models to determine associations between the behaviors and perceived exertion, measured on a numeric rating scale (0-10), and included interactions between each behavior and psychosocial resources (influence at work, social support, and quality of leadership) to determine a possible moderating effect of resources. Regression results were illustrated using isotemporal substitution. RESULTS: Sitting was negatively (ß: -0.64; P < 0.01) while MVA was positively (ß: 0.95; P = 0.02) associated with perceived exertion. According to isotemporal substitution, replacing 30 min of MVA by sitting would, for an average worker, be associated with a decrease in physical exertion by -0.14 on the 0-10 scale. Job resources marginally moderated the association between LA and exertion. Thus, among workers with low influence and low social support, we found a positive association between LA and exertion, while that was not found for workers with medium or high influence and support (interactions for influence and support: P = 0.08 and P = 0.10). CONCLUSIONS: Our findings suggest that reallocating time from MVA to sitting can mitigate perceived physical exertion in eldercare workers. More time in LA increased physical exertion only for workers with low psychosocial resources, supporting a positive effect of a better psychosocial work environment in elderly care.

Does sEMG normalization change results on sex differences in the activation of the shoulder girdle muscles during a simulated work task?

The aim was to investigate if the method of normalizing surface electromyography (sEMG) can change results on sex differences in the muscular activation of the shoulder girdle muscles during a simulated work task. sEMG was recorded in 36 asymptomatic participants (17 females, 19 males) from four parts of trapezius and from serratus anterior muscles during a simulated work task. Four normalization methods, one involving maximal voluntary contractions (MVCs) and three involving submaximal voluntary contractions were applied. Sex differences in absolute and normalized amplitude of sEMG were analyzed. The normalization method had a significant influence on the observed sex differences. Females only showed higher sEMG amplitude than males when the sEMGs were normalized to MVC and to a submaximal contraction based on 20% of MVC for the upper trapezius (acromial fibers). Researchers and practitioners should be aware of the impact of the sEMG normalization method in sex differences investigation.

Association between Psychosocial Working Conditions and Perceived Physical Exertion among Eldercare Workers: A Cross-Sectional Multilevel Analysis of Nursing Homes, Wards and Workers.

This cross-sectional multilevel study aims at investigating the associations between psychosocial working conditions of different workplace levels and perceived physical exertion among eldercare workers. Data were obtained from the 'Danish Observational Study of Eldercare work and musculoskeletal disorderS' (DOSES) study, including 536 eldercare workers, nested in 126 wards and 20 nursing homes. Psychosocial working conditions were measured by the Copenhagen Psychosocial Questionnaire (COPSOQ). The physical workload was measured with a self-administered scale (0-10) rating perceived physical exertion. Multilevel linear mixed models were used to determine associations of psychosocial conditions between nursing homes, wards, and workers with physical exertion. Most of the variance in the perceived physical exertion was explained by differences between workers (83%), but some variance was explained by wards (11%) and nursing homes (6%). Workers employed in nursing homes with low influence (p = 0.01) and poor leadership (p = 0.02), and in wards with high quantitative demands (p = 0.03), high work pace (p < 0.001), and low justice (p = 0.01) were at increased risk of reporting higher physical exertion. The strongest associations were found for low influence, low quality of leadership, and high work pace at nursing homes and ward levels. In conclusion, improving specific psychosocial working conditions at nursing home and ward levels may be of particular importance to reduce excessive physical workload in eldercare workers.

Are there sex differences in muscle coordination of the upper girdle during a sustained motor task?

PURPOSE: The higher prevalence of work-related musculoskeletal disorders among women compared with men could be explained by sex-gender differences related to biological and physiological processes. The aim of this study was to evaluate sex differences in motor coordination during a sustained and repetitive motor task. METHODS: Seventeen healthy females and 21 healthy males participated. The surface electromyography (sEMG) of the trapezius portions and serratus anterior were recorded. Root mean square (RMS) values were computed to assess the level of muscle activity. The standard deviation (SD) and coefficient of variation (CV) were computed as metrics of size of variability. The normalized mutual information (NMI) values were calculated as index of functional connectivity between muscles pairs. RESULTS: Females had higher normalized RMS values for the upper trapezius (acromial fibers) and serratus anterior muscles compared with males. RMS decreased, SD and CV increased while NMI decreased for almost all muscle pairs over time. CONCLUSION: The present work showed some signs of sex differences in muscle coordination of the shoulder girdle during a sustained motor task, performed with the upper limb positioned below of the shoulder level.

Surface electromyography in inspiratory muscles in adults and elderly individuals: A systematic review.

INTRODUCTION: Electromyography (EMG) helps to evaluate disorders and pulmonary behavior, as impairments in respiratory muscle function are associated with the development of diseases. There is a wide range of methods and protocols used to record and analyze EMG obtained from respiratory muscles, demonstrating a lack of standardization. OBJECTIVE: To identify the most common procedures used to record surface EMG (sEMG) of inspiratory muscles in adults and elderly individuals through a systematic review (primary), and to evaluate the quality of the report presented by the studies (secondary). METHOD: Studies published from January 1995 until June 2018 were searched for in the Web of Science, PubMed, LILACS, EBSCO and Embase databases. Only studies evaluating sEMG of inspiratory muscles were included. RESULTS: The electronic search retrieved a total of 6697 titles and 92 of them were included. A great variability on the methods applied to both recording and processing/analyzing data was found. Therefore, the synthesis of practical/clinical evidence to support immediate recommendations was impaired. In general, the descriptions presented by the studies are poor. CONCLUSION: The most common procedures used for sEMG were identified. Methodological studies with objective comparisons were fundamental for improving standardization, given the impossibility of recommendations from this review.

Adding Handles to Optimize Manual Box Handling.

The risk factors for developing musculoskeletal disorders in material handling tasks are well known. Among strategies for controlling risks, modifying boxes by adding handles is suggested. However, there are no clear recommendations regarding box modification as an approach to improve musculoskeletal health. In this study, we investigated the main literature databases to identify effects of box modification on reducing physical load. Electronic and manual searches were performed to identify studies that evaluated effects of boxes handles on physical exposure during handling tasks. The included studies were very heterogeneous (methods of assessment, types of handles used, and methodological quality), jeopardizing synthesis of evidence. Despite the mentioned limitations, we could suggest some features that could improve manual handling in practical settings, like the use of cylindrical handles forms with intermediate diameters (between 31 and 51 mm) and 30° inclination. Those characteristics demonstrated positive results on physical exposure. Regular cut-outs were indicated as a beneficial approach when boxes are handled in high surfaces. When handling occurs in medium heights or in the floor level, handles positioned on the top of the box might bring better results. Efforts to standardize methods are important to support both objective and subjective assessment of box handle design, as well to improve the internal validity of studies.

Comparison of muscle activity from upper trapezius and wrist extensors between dominant and non-dominant upper limbs during computer-based tasks.

BACKGROUND: Sustained low-level muscle activity occurring during computer-based tasks is associated with the development of WMSDs (work-related musculoskeletal disorders) and this biomechanical exposure may be different between limbs. OBJECTIVE: To compare muscle activity from dominant and non-dominant upper trapezius (UT) and wrist extensors (WE) during computer-based tasks in real work settings. METHODS: Forty-five workers were monitored during two hours while performing their usual administrative tasks. Surface electromyography (sEMG) was recorded from UT and WE muscles in both sides. Rest and general exposure variables were calculated. RESULTS: The 50th percentile demonstrated little muscle activity demand, for both dominant and non-dominant UT and no difference between sides was observed. The dominant WE muscles had lower measures of rest and higher muscle activity when compared with the non-dominant side. CONCLUSIONS: Differences in sEMG between upper limbs were only found in WE muscles, probably due to the use of the mouse. The overall low-level muscle activity suggests a constant activation of the same motor units for the entire data-collection period, which can be considered harmful for musculoskeletal health.

Can exposure variation be promoted in the shoulder girdle muscles by modifying work pace and inserting pauses during simulated assembly work?

This study investigated the acute effects of changing the work pace and implementing two pause types during an assembly task. Eighteen healthy women performed a simulated task in four different conditions: 1) slow or 2) fast work pace with 3) passive or 4) active pauses every two minutes. The root mean square (RMS) and exposure variation analysis (EVA) from the trapezius and serratus anterior muscles, as well as the rate of perceived exertion (RPE) from the neck-shoulder region, were observed. Decreased RMS and RPE as well as more variable muscle activity (EVA) were observed in the slow work pace compared with the fast one. The pause types had a limited effect, but active pauses resulted in increased RMS of the clavicular trapezius. The findings revealed the importance of work pace in the reduction of perceived exertion and promotion of variation in muscle activation during assembly tasks. However, the pause types had no important effect on the evaluated outcomes.

Normalization of the trapezius sEMG signal - a reliability study on women with and without neck-shoulder pain.

OBJECTIVE: To evaluate within- and between-days reliability of two normalization methods of surface electromyography (sEMG) recordings of the trapezius muscle. METHODS: Nineteen women were allocated into 2 groups (healthy and with neck-shoulder pain). The sEMG was recorded in two sessions with 7 days in between sessions. The four portions of the trapezius muscle (the clavicular and acromial fibers of the upper trapezius, the middle and the lower trapezius) were evaluated during maximal and submaximal isometric voluntary contractions. The within- and between-days reliability of both maximal and submaximal contractions were assessed through Intraclass Correlation Coefficient (ICC(2,1) was used for within-day analyses of both maximal and submaximal contractions, and for between-days analyses of maximal contractions while ICC(2,3) was used for between-days analyses of submaximal contractions), Coefficient of Variation, Standard Error of Measurement, and Bland-Altman analysis. RESULTS: In general, submaximal contractions presented higher within-day reliability, with higher ICC values (e.g., middle trapezius - mean of 0.97), smaller Coefficient of Variation and Standard Error of Measurement ranges compared to maximal contractions (ICC values, e.g. for middle trapezius - mean of 0.94) in both groups. The same pattern was observed for between-days analyses, with submaximal contractions presenting higher ICC values (e.g., middle trapezius - mean of 0.84), smaller Coefficient of Variation and Standard Error of Measurement ranges than maximal contractions (ICC values, e.g. for middle trapezius - mean of 0.73) in both groups. CONCLUSION: Submaximal contractions are recommended for normalization procedures of trapezius sEMG, in both subjects with neck-shoulder pain and healthy individuals.

The coordination of shoulder girdle muscles during repetitive arm movements at either slow or fast pace among women with or without neck-shoulder pain.

PURPOSE: The aim of this study was to evaluate the coordination of the shoulder girdle muscles among subjects with or without neck-shoulder pain performing repetitive arm movement at either a slow or fast pace. METHODS: Thirty female adults were allocated to one of two groups-healthy controls or cases with neck-shoulder pain. Surface electromyography (sEMG) signals from the clavicular, acromial, middle and lower trapezius portions and the serratus anterior muscles were recorded during a task performed for 20min at a slow pace and 20min at a fast pace. The root mean square (RMS), relative rest time (RRT) and normalised mutual information (NMI, an index of functional connectivity between two muscles in a pair) were computed. RESULTS: No significant differences on RMS, RRT and NMI were found between groups. For both groups, the fast movement pace resulted in increased levels of RMS, lower degrees of RRT and higher NMI compared to the slow pace. No interaction between group and movement pace was found. CONCLUSIONS: This study highlights the change in sEMG activity of muscles to meet the demands of performing a task at fast movement pace. The fast pace imposed a higher muscle demand evidenced by increased sEMG amplitude, low degree of muscle rest and increased functional connectivity for subjects in both the case and control groups. No indication of impaired sEMG activity was found in individuals with neck-shoulder pain.

Effects of active pause pattern of surface electromyographic activity among subjects performing monotonous tasks: A systematic review.

Active pauses have shown potentially beneficial effects to increase the variability of the electrical activation pattern of muscles. However, there is a lack of consensus as to how to design and implement those pauses and the processing methods of surface electromyography (EMG) data when evaluating low-level monotonous tasks. The aim of this systematic review was to synthesize the evidences regarding the way which active pauses have been applied, and the methods used to investigate the related EMG changes. PubMed-MEDLINE, Embase, Web of Science, Lilacs, Ebsco, and Scopus databases were searched. Two authors independently extracted data from the primary studies. The methodological quality was assessed using a list from van der Windt et al. (2000), and the level of evidence was synthesized through GRADE. The ISEK guideline for reporting EMG data was also applied as a checklist. Fifteen studies were included - 14 with high methodological quality. In general, active pauses were able to change the level of EMG activity in monotonous tasks. The level of evidence through GRADE was very low for all EMG processing methods, except RMS which was low. A vast heterogeneity concerning the methods applied to analyze EMG data contributed to decrease the quality of evidence synthesis, and the findings need to be carefully considered. The GRADE approach and the ISEK guideline contributed to identify important flaws in the literature. Future studies investigating active pauses in longitudinal studies and following the standard for recording and reporting EMG data care are warranted.