Muscular and Vascular Issues Induced by Prolonged Standing With Different Work-Rest Cycles With Active or Passive Breaks

Changes in Baropodometric Evaluation and Discomfort during the Workday in Assembly-Line Workers

Prolonged standing at work is associated with health risks. The appearance of lower-limb and lower-back discomfort is one of the most prevalent factors in prolonged standing workers. The aim of this research was to evaluate the effect of an eight-hour workday on foot pressure and musculoskeletal discomfort in standing workers. Thirty-six assembly-line workers (six women) were recruited to participate in a cross-sectional study to assess foot pressure and surface, foot, knee, and lower-back discomfort before and after a real workday. Baropodometry outcomes (surface and pressure) were evaluated by the pressure platform SensorMedica and musculoskeletal discomfort was evaluated by Cornell's Musculoskeletal Discomfort Questionaire. Total foot surface (p = 0.01) and foot discomfort (p = 0.03) increased significantly at the end of the workday. Prolonged standing during 8 h workday increased the foot discomfort and total foot surface in assembly-line workers. No foot pressure variable (forefoot, rearfoot, or total) was significantly modified after the workday in assembly-line workers.

Comparison of Physiological Effects Induced by Two Compression Stockings and Regular Socks During Prolonged Standing Work

OBJECTIVE

The goal of this study was to evaluate and compare lower-leg muscle fatigue, edema, and discomfort induced by the prolonged standing of security guards wearing regular socks and those wearing 15-20 or 20-30 mmHg compression stockings as intervention.

BACKGROUND

Compression stockings are sometimes used by individuals standing all day at work. However, quantitative evidence showing their potential benefits for lower-leg health issues in healthy individuals during real working conditions is lacking.

METHOD

Forty male security employees participated in the study. All were randomly assigned to the control or one of the two intervention groups (I15-20 or I20-30). Lower-leg muscle twitch force, volume, and discomfort ratings were measured before and after their regular 12-hr standing work shift.

RESULTS

Significant evidence of lower-leg long-lasting muscle fatigue, edema, and discomfort was observed after standing work for guards wearing regular socks. However, no significant changes were found for guards wearing either compression stockings.

CONCLUSION

In healthy individuals, compression stockings seem to attenuate efficiently the tested outcomes in the lower leg resulting from prolonged standing.

APPLICATION

Occupational activities requiring prolonged standing may benefit from 15-20 or 20-30 mmHg compression stockings. As similar benefits were observed for both levels of compression, the lower level may be sufficient.

Comparison of intermittent pneumatic compression device and compression stockings for workers with leg edema and pain after prolonged standing: a prospective crossover clinical trial

BACKGROUND

During prolonged standing, insufficient calf muscle pumping accompanies venous stasis and hypertension in the lower legs, resulting in valve dysfunction, venous wall problems, and sub-sequent inflammation. Compression therapy, which includes medical compression stockings (MCS) and mechanical intermittent pneumatic compression (IPC), is one of the most effective therapeutic interventions for treating chronic venous diseases. This study aimed to compare the therapeutic effect among resting, IPC and MCS alone, and IPC with MCS in long-standing workers (> 8 h daily).

METHODS

This crossover trial was conducted with 39 participants with complaints of leg edema and pain whose work involved standing for more than 8 h daily. Four treatment protocols were established for each visit as follows: protocol A (not wear MCS during work and rest without IPC after work), protocol B (wear MCS during work and rest without IPC after work), protocol C (not wear MCS during work and treat with IPC after work), and protocol D (wear MCS during work and treat with IPC after work). The primary outcome was the visual analogue scale (VAS) score for leg pain. The secondary outcomes were leg volume (mL), circumference (cm), extracellular fluid/total body fluid (ECF/TBF), and extracellular water/total body water (ECW/TBW) through bioelectrical impedance analysis. Outcomes were assessed before work (T0), after work (T1), and 60 min after intervention (T2).

RESULTS

All four protocols had significantly increased leg pain after work (T0-1) but improved 60 min after intervention (T1-2), particularly protocol C (decreased VAS by 1.9). When leg swelling was compared at T0 and T1, protocols A and C showed significant increases in leg volume and circumference, indicating significant work-induced edema, whereas protocols B and D showed no change or even a decrease. After interventions, leg volume and circumference significantly decreased in protocols A and C, although protocols B and C did not show significant improvement. The ECF/TBF and ECW/TBW of all protocols decreased after interventions.

CONCLUSIONS

Leg pain and edema after prolonged standing (T1-T2) in adults were safely and effectively improved by both IPC alone and IPC with MCS. Although the use of MCS during the workday did not show improvement in leg pain immediately after work (T0-T1), both MCS with resting and MCS with IPC decreased leg pain at T1-T2 and prevented leg edema at T0-T1.

TRIAL REGISTRATION

This trial protocol was registered at the Clinical Research Information Service (KCT0005383, the date of first registration: 08/09/2020).

Nonlinear analysis of postural changes related to the movement interventions during prolonged standing task

This study assessed the effects of movement-based interventions on the complexity of postural changes during prolonged standing. Twenty participants, equally distributed in gender and standing work experience (SWE), completed three simulated prolonged standing sessions: without movement (control), leg exercise and footrest. The amount and complexity of variability in the centre of pressure (COP) and lumbar curvature angle were quantified using linear and nonlinear tools. Lower leg swelling and back/leg discomfort were also monitored. Participants in the SWE group showed significantly greater postural complexity during the standing. Regular leg exercise resulted in significantly higher postural complexity and lower leg discomfort and swelling. The footrest led to significant changes in amount of COP variability. Both interventions significantly reduced back discomfort. Overall, the nonlinear analysis of postural changes provided different findings compared to linear ones, considering the standing time, interventions and standing job experience. Nonlinear results were consistent with leg discomfort and swelling. Practitioner summary: The effect of movement-based interventions on dynamics of postural alterations over prolonged standing were characterised using nonlinear techniques. The effect of standing work experience was also considered. Previous experience of standing jobs and leg movements increase the complexity of postural behaviour over standing period.

Shank Circumference Reduction by Sleep Compression Stockings in University Students and Convenience Store Cashiers

Compression stockings (CSs) are a relatively simple and effective tool for alleviating varicose veins and are often used as a preventive measure among workers whose jobs require prolonged standing. Nevertheless, the efficacy of CSs that are advertised as sleepwear remains unverified. This study recruited 10 female university students and 10 cashiers as participants to test the effects of sleep CSs. During the experiment, the changes in shank circumference (SC) and the subjective discomfort rating upon getting up and going to bed were collected. Data were recorded immediately after getting up and SC measurement was repeated 10 min later. The results demonstrated that both CS condition and measurement time significantly affected SC reduction, whereas cashier or student status did not. The reported discomfort and tightness of the legs attributed to CSs were relatively high, and the benefit toward SC reduction was minimal. Cashiers exhibited slightly larger SC values and higher perceived discomfort levels, which may be attributed to their occupational characteristic of prolonged standing, and the cumulative effect of prolonged standing on muscle properties warrants further study. The study findings suggest that wearing CSs for sleep may not be effective for reducing OE

The effect of walking and stationary work on the acute back pain, muscle activation, posture and postural control of older women

Back pain is associated with activity such as walking or assembly line work that involves upper-body movement. However, no single study has explored the effect of these tasks on back pain, spinal angles and balance in an older adult female population. This study investigated changes in back pain, postural sway, upper-, lower- and full-spine angle and EMG activation of trunk muscles following 30 minutes of walking and a modified quiet standing task. Fourteen older adult females (62 ± 11yrs) with low to moderate chronic back pain were recruited as participants. Findings demonstrated that following these activities, increased acute back pain and upper-spine flexion occur although acute back pain was not clinically significant; postural control and muscle activation remained unchanged. This suggests that walking and modified quiet standing can lead to subtle acute back pain in older females that could be due to an increased upper spinal flexion rather than muscle fatigue. Practitioner summary: Back pain and postural problems are common in older adults. Older adult female participants experienced increased back pain and greater upper-spine flexion following 30-minute walking and standing with trunk rotation, but the practical importance was less clear. However, balance was unaffected, suggesting no increase in fall risk. Abbreviations: CBP: chronic back pain; MQS: modified quiet standing; QS: quiet standing; RPE: rating of perceived exertion; TD: trapezius descendens; TT: trapezius transversalis; TA: trapezius ascendens; ESL: erector spinae longissimus; C7: seventh cervical vertebrae; T7: seventh thoracic vertebrae; T10: tenth thoracic vertebrae; T12: twelfth thoracic vertebrae; L2: second lumbar vertebrae; S2: second sacral vertebrae; AP: anterior-posterior; ML: medial-lateral; SWAYtot: total postural sway; M: mean.

Different sit:stand time ratios within a 30-minute cycle change perceptions related to musculoskeletal disorders

Regular standing interruptions to sedentary work are recommended, but their dosage is understudied. To measure perception variations associated with different sit:stand ratios, 16 people used six ratios (30:0, 27:3, 24:6, 21:9, 18:12 and 15:15) within 30-min cycles in their normal office environment. At start and end of each workday, study participants recorded their perception of 11 factors on a 10-point scale. Musculoskeletal discomfort in 10 body regions was measured before and after exposure to sit-stand ratios. Overall preferred ratios were recorded. Sit:stand ratio affected all perceived factors, with impact varying. Standing at least 6 min improved results most overall; however, individual perceived factors were least impacted by any of 30:0, 27:3, 24:6 or 21:9. Preferred sit:stand ratios were 15:15, 18:12 and 21:9. Typically, least liked ratios involved briefest standing (30:0, 27:3, 24:6) although two participants least liked 15:15. Understanding these variations contributes to appropriate standing dosage recommendations.

Modeling and Validation of Fatigue and Recovery of Muscles for Manual Demolition Tasks

Manual demolition tasks are heavy, physically demanding tasks that could cause muscle fatigue accumulation and lead to work-related musculoskeletal disorders (WMSDs). Fatigue and recovery models of muscles are essential in understanding the accumulation and the reduction in muscle fatigue for forceful exertion tasks. This study aims to explore the onset of muscle fatigue under different work/rest arrangements during manual demolition tasks and the offset of fatigue over time after the tasks were performed. An experiment, including a muscle fatigue test and a muscle fatigue recovery test, was performed. Seventeen male adults without experience in demolition hammer operation were recruited as human participants. Two demolition hammers (large and small) were adopted. The push force was either 20 or 40 N. The posture mimicked that of a demolition task on a wall. In the muscle fatigue test, the muscle strength (MS) before and after the demolition task, maximum endurance time (MET), and the Borg category-ratio-10 (CR-10) ratings of perceived exertion after the demolition task were measured. In the muscle fatigue recovery test, MS and CR-10 at times 1, 2, 3, 4, 5, and 6 min were recorded. Statistical analyses were performed to explore the influence of push force and the weight of the tool on MS, MET, and CR-10. Both muscle fatigue models and muscle fatigue recovery models were established and validated. The results showed that push force affected MET significantly (p < 0.05). The weight of the tool was significant (p < 0.05) only on the CR-10 rating after the first pull. During the muscle fatigue recovery test, the MS increase and the CR-10 decrease were both significant (p < 0.05) after one or more breaks. Models of MET and MS prediction were established to assess muscle fatigue recovery, respectively. The absolute (AD) and relative (RD) deviations of the MET model were 1.83 (±1.94) min and 34.80 (±31.48)%, respectively. The AD and RD of the MS model were 1.39 (±0.81) N and 1.9 (±1.2)%, respectively. These models are capable of predicting the progress and recovery of muscle fatigue, respectively, and may be adopted in work/rest arrangements for novice workers performing demolition tasks.

Determining the interactions between postural variability structure and discomfort development using nonlinear analysis techniques during prolonged standing work

PURPOSE

Nonlinear analysis techniques provide a powerful approach to explore dynamics of posture-related time-varying signals. The aim of this study was to investigate the fundamental interactions between postural variability structure and discomfort development during prolonged standing.

METHODS

Twenty participants, with equal distribution for gender and standing work experience (SWE), completed a simulated long-term standing test. Low back and legs discomfort, center of pressure, lumbar curvature, and EMG activity of trunk and leg muscles were monitored. Nonlinear measures including largest lyapunov exponent, multi-scale entropy, and detrended fluctuation analysis were applied to characterize the variability structure (i.e., complexity) in each signal. The size (i.e., amount) of variability was also computed using traditional linear metrics.

RESULTS

With progress of low back and legs discomfort over standing periods, significant lower levels were perceived by the participants having SWE. The amount of variability in all signals (except external oblique EMG activity) were significantly increased with the time progress for all participants. The structure of variability in most signals demonstrated a lower complexity (more regularity) with fractal properties that deviated from 1/f noise. The SWE group showed a higher complexity levels.

CONCLUSIONS

Overall, the findings verified variations in structure and amount of the postural variability. However, nonlinear analysis identified postural strategies according to the perceived discomfort in a different way. These results provide supports for future application of nonlinear tools in evaluating standing tasks and related ergonomics interventions as it allows further insight into how discomfort development impact the structure of postural changes.

Intermittent pneumatic compression for prolonged standing workers with leg edema and pain

Even healthy individuals often encounter leg venous symptoms such as heaviness, pain, and swelling especially after prolonged standing work. Intermittent pneumatic compression (IPC) is a widely used simple therapy for preventing deep vein thrombosis and for treating lymphedema and chronic venous insufficiency. However, IPC has not been evaluated for its effect in relieving venous symptoms of healthy people.This was single center, cross-over study to investigate the effect of IPC for 20 healthy volunteers who usually stand on duty and complain of leg pain and swelling. The primary outcome was pain (measured using a visual analogue scale) and secondary outcomes were leg circumference and volume. Three different interventions included natural rest, sequential mode of IPC, and circular mode of IPC. Outcomes were measured before work and immediately after work (T1), after 30 minutes of intervention (T2), and 30 minutes of rest after intervention (T3).Pain and leg circumferences were significantly improved at T2 and T3 compared with those at T1. Sequential and circular IPC led to significantly greater improvement in pain and leg circumferences than just natural rest, but there was no difference in its effect according to the 2 modes of IPC. Leg volume was reduced significantly at T2 and T3 as compared with T1 in all 3 interventions, but effects did not differ among 3 intervention groups.IPC is effective for reducing leg pain and circumferences more than natural rest in healthy adults with prolonged standing work, without causing adverse events.

The Influence of Sitting, Standing, and Stepping Bouts on Cardiometabolic Health Markers in Older Adults

Aside from total time spent in physical activity behaviors, how time is accumulated is important for health. This study examined associations between sitting, standing, and stepping bouts, with cardiometabolic health markers in older adults. Participants from the Mitchelstown Cohort Rescreen Study (N = 221) provided cross-sectional data on activity behaviors (assessed via an activPAL3 Micro) and cardiometabolic health. Bouts of ≥10-, ≥30-, and ≥60-min sitting, standing, and stepping were calculated. Linear regression models were fitted to examine the associations between bouts and cardiometabolic health markers. Sitting (≥10, ≥30, and ≥60 min) and standing (≥10 and ≥30 min) bouts were detrimentally associated with body composition measures, lipid markers, and fasting glucose. The effect for time spent in ≥60-min sitting and ≥30-min standing bouts was larger than shorter bouts. Fragmenting sitting with bouts of stepping may be targeted to benefit cardiometabolic health. Further insights for the role of standing need to be elicited.

A PRELIMINARY ASSESSMENT OF PHYSICAL WORK EXPOSURES AMONG ELECTRONIC WASTE WORKERS AT AGBOGBLOSHIE, ACCRA GHANA

Occupational exposure associated with unstructured, informal e-waste recycling has received very limited attention. This study aimed to quantify the occupational physical exposures among informal e-waste workers at the largest e-waste site in Africa. A cross-sectional field survey of 163 male e-waste workers was conducted using a self-report occupational physical activity questionnaire, along with direct work observations, and pedometer estimates of walking activity for a subset of workers (n = 42). Results indicated significant differences in self-reported 7-day work exposures among the three main e-waste job categories, namely, collectors (n = 70), dismantlers (n = 73) and burners (n = 20). Prolonged walking, sitting and standing on five or more days in the workweek was frequently reported by collectors (87%), dismantlers (82%) and burners (60%), respectively. Nearly 90% of collectors and burners and 60% of dismantlers reported lifting and carrying on five or more days in the workweek. The exposure combinations identified suggest a risk for musculoskeletal disorders (MSDs). Findings call attention to the need for research examining potential associations between physical exposures and MSDs affecting e-waste workers in Agbogbloshie. The high exposure variability both between and within workers has implications for future exposure assessments conducted in unregulated, informal work settings.

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.

Posture and Time Arrangement Influence Shank Circumference Reduction When Performing Leg Raising Exercise

This study recruited nine young women who performed a leg raising exercise under six test combinations of three holding postures (lying supine, placing the shanks on a yoga ball, and elevating the legs at 60° against the wall) and two time arrangements (continuous vs. intermittent) for a period of 15 min. The intermittent arrangement included an additional 1-min rest set in the middle of the 15 min test. The participants' shank circumference (SC) reductions and discomfort ratings were measured after each test combination was performed. Results indicated that the most efficient method for SC reduction was the yoga ball (5.4 mm), followed by the supine lying posture (4.6 mm) and wall-supported leg raising (3.1 mm). A significant interaction of posture × time arrangement (p < 0.01) implied that the yoga ball method combined with a 1-min rest produced the greatest SC reduction (6.7 mm). Our results also showed that participants experienced the greatest discomfort (score: 4.96) when performing wall-supported leg raising, compared with both lying supine (score: 1.34) and the yoga ball (score: 1.32). This study suggests that the effectiveness of leg raising as conventionally practiced for eliminating leg fatigue or swelling requires further consideration.

Physiological changes during prolonged standing and walking considering age, gender and standing work experience

Occupational standing is associated with musculoskeletal and venous disorders. The aim was to investigate whether lower leg oedema and muscle fatigue development differ between standing and walking and whether age, gender and standing work habituation are factors to consider. Sixty participants (15 young females, 15 young males, 15 older males, and 15 young males habituated to standing work) were included and required to stand/walk for 4.5 hours in three periods with two seated breaks. Waterplethysmography/bioelectrical impedance, muscle twitch force and surface electromyography were used to assess lower leg swelling (LLS) and muscle fatigue as well as gastrocnemius muscle activity, respectively. While standing led to LLS and muscle fatigue, walking did not. Low-level medial gastrocnemius activity was not continuous during standing. No significant influence of age, gender and standing habituation was observed. Walking can be an effective prevention measure to counteract the detrimental effects of quasi-static standing.Practitioner summary: Prolonged standing leads to lower leg oedema and muscle fatigue while walking does not. The primary cause of fatigue may be in other muscles than the medial gastrocnemius. Walking may be an effective prevention measure for health risks of occupational standing when included intermittently.Abbreviation: BI: bioelectrical impedance; LLS: lower leg swelling; SEMG: surface electromyography; MTF: muscle twitch force; WP: waterplethysmography; Bsl: Baseline; L: Lunch; E: Evening; MTM: method times measurement; EA: electrical activity; IQR: interquartile range; p: percentile; M: mean; SE: standard error; Adj: adjusted.

It is Time to Have Rest: How do Break Types Affect Muscular Activity and Perceived Discomfort During Prolonged Sitting Work

Background

Prolonged sitting at work can lead to adverse health outcomes. The health risk of office workers is an increasing concern for the society and industry, with prolonged sitting work becoming more prevalent.

Objective

This study aimed to explore the variation in muscle activities during prolonged sitting work and found out when and how to take a break to mitigate the risk of muscle symptoms.

Methods

A preliminary survey was conducted to find out the prevalence of muscle discomfort in sedentary work. Firstly, a 2-h sedentary computer work was designed based on the preliminary study to investigate the variation in muscle activities. Twenty-four participants took part in the electromyography (EMG) measurement study. The EMG variations in the trapezius muscle and latissimus dorsi were investigated. Then the intervention time was determined based on the EMG measurement study. Secondly, 48 participants were divided into six groups to compare the effectiveness of every break type (passive break, active break of changing their posture, and stand and stretch their body with 5 or 10 mins). Finally, data consisting of EMG amplitudes and spectra and subjective assessment of discomfort were analyzed.

Results

In the EMG experiment, results from the joint analysis of the spectral and amplitude method showed muscle fatigue after about 40 mins of sedentary work. In the intervention experiment, the results showed that standing and stretching for 5 mins was the most effective break type, and this type of break could keep the muscles' state at a recovery level for about 30−45 mins.

Conclusions

This study offers the possibility of being applied to office workers and provides preliminary data support and theoretical exploration for a follow-up early muscle fatigue detection system.

Physiological and neuromotor changes induced by two different stand-walk-sit work rotations

The potential of rotating postures to alleviate the effects of prolonged standing and sitting postures has been advocated to attenuate the accumulation of muscle fatigue, considered a precursor to musculoskeletal disorders. We aimed to evaluate the effects of two posture rotations, both including standing, walking, sitting, on physiological and neuromotor measures. Twenty-two participants followed two posture rotations, with different rest-break distributions, for 5.25 h. Lower-leg muscle twitch force, volume, force control and discomfort perception were evaluated during and after work exposure on two non-consecutive days. Significant changes in all measures indicate a detrimental effect in lower-leg long-lasting muscle fatigue, oedema, performance and discomfort after 5 h for both exposures. However, for both exposures recovery was significant 1 h and 15 h post-workday. Differences between the two rotation schedules were not significant. Hence, stand-walk-sit posture rotation promotes recovery of the tested measures and is likely to better prevent muscle fatigue accumulation. Practitioner summary: Lower-leg muscle twitch force, volume, force control, and discomfort were quantified during and after 5 h of stand-walk-sit work rotations with two different rest-break distributions. Measures revealed similar significant effects of work exposures regardless of rotation; which did not persist post-work. This beneficial recovery contrasts with the standing only situations. Abbreviations: MSDs: musculoskeletal disorders; MTF: muscle twitch force; RMSE: root mean square error; MVC: maximum voluntary contraction; M: mean; SE: standard error.

Methods in Experimental Work Break Research: A Scoping Review

The number of studies on work breaks and the importance of this subject is growing rapidly, with research showing that work breaks increase employees’ wellbeing and performance and workplace safety. However, comparing the results of work break research is difficult since the study designs and methods are heterogeneous and there is no standard theoretical model for work breaks. Based on a systematic literature search, this scoping review included a total of 93 studies on experimental work break research conducted over the last 30 years. This scoping review provides a first structured evaluation regarding the underlying theoretical framework, the variables investigated, and the measurement methods applied. Studies using a combination of measurement methods from the categories “self-report measures,” “performance measures,” and “physiological measures” are most common and to be preferred in work break research. This overview supplies important information for ergonomics researchers allowing them to design work break studies with a more structured and stronger theory-based approach. A standard theoretical model for work breaks is needed in order to further increase the comparability of studies in the field of experimental work break research in the future.