The effects of prolonged sitting, standing, and an alternating sit-stand pattern on trunk mechanical stiffness, trunk muscle activation and low back discomfort

A Novel IMU-Based System for Work-Related Musculoskeletal Disorders Risk Assessment

This study introduces a novel wearable Inertial Measurement Unit (IMU)-based system for an objective and comprehensive assessment of Work-Related Musculoskeletal Disorders (WMSDs), thus enhancing workplace safety. The system integrates wearable technology with a user-friendly interface, providing magnetometer-free orientation estimation, joint angle measurements, and WMSDs risk evaluation. Tested in a cable manufacturing facility, the system was evaluated with ten female employees. The evaluation involved work cycle identification, inter-subject comparisons, and benchmarking against standard WMSD risk assessments like RULA, REBA, Strain Index, and Rodgers Muscle Fatigue Analysis. The evaluation demonstrated uniform joint patterns across participants (ICC=0.72±0.23) and revealed a higher occurrence of postures warranting further investigation, which is not easily detected by traditional methods such as RULA. The experimental results showed that the proposed system's risk assessments closely aligned with the established methods and enabled detailed and targeted risk assessments, pinpointing specific bodily areas for immediate ergonomic interventions. This approach not only enhances the detection of ergonomic risks but also supports the development of personalized intervention strategies, addressing common workplace issues such as tendinitis, low back pain, and carpal tunnel syndrome. The outcomes highlight the system's sensitivity and specificity in identifying ergonomic hazards. Future efforts should focus on broader validation and exploring the relative influence of various WMSDs risk factors to refine risk assessment and intervention strategies for improved applicability in occupational health.

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.

Female Surgical Ergonomics in Otolaryngology: A National Survey Study

OBJECTIVE

To assess the nature and impact surgical ergonomic challenges experienced by female otolaryngologists.

STUDY DESIGN

National survey study.

SETTING

Female otolaryngology residents, fellows and attendings recruited via social media posting and email distribution.

METHODS

We distributed a survey study to female otolaryngologists throughout the United States. The height and glove size of participants reporting difficulties with equipment and instruments were compared to those not reporting difficulties.

RESULTS

Ninety-six female otolaryngologists participated in our study, comprised of 43% residents, 10% fellows, and 47% attendings. Ninety percent of participants reported difficulties using equipment and 77% of participants reported difficulty with instruments, the most common being nasal endoscopic instruments (28%). The vast majority of participants reported pain during and (or) after the operation (92%). Head and neck (53%) and rhinology (44%) were identified as particularly challenging specialities, but only 25% of participants reported that ergonomics affected their career plans. Participants felt that adjustable equipment (60%), a variety of sizes of instruments (43%), and more discussion around ergonomics (47%) would help. Respondents reported adjusting the operating room to accommodate their size took extra time (44%) and was a mental burden (39%). Participants reporting difficulties with operating room equipment were significantly shorter than those without difficulties (64 inches vs 67 inches, P = .037), and those reporting difficulties with instruments had a smaller median glove size (6 vs 6.5, P = .018).

CONCLUSION

Surgical ergonomics represent a challenge for female otolaryngologists, particularly those with smaller hands and shorter height. Partnering with industry, we must address the needs of an increasingly diverse workforce to ensure that all surgeons can operate effectively and comfortably.

Prevalence of Low Back Pain Among University Attendants in Tabuk City During 2023: A Cross-Sectional Study in Saudi Arabia

BACKGROUND

College students are at a higher risk of suffering low back pain (LBP). Assessing the magnitude of the problem and the associated risk factors can help reduce the suffering and disability in future doctors.

AIM

This study was conducted to investigate the prevalence and related factors of LBP among medical students in the University of Tabuk and emphasize the need for targeted interventions that could help alleviate the burden of LBP among the students and improve their quality of life.

METHODS

This cross-sectional study used an online well-structured, self-report questionnaire to collect the respondents' data. The questionnaire explored the participants' sociodemographic factors, lifestyle, and the severity of LBP-related disability using the modified Oswestry Low Back Pain Disability Questionnaire (Oswestry Disability Index (ODI)) score.

RESULTS

The prevalence rate of LBP was 26.8%. The independent factors that significantly increased the probability of LBP included overweight/obesity (odds ratio (OR): 1.696, 95% confidence interval (CI): 1.086 to 2.648, p = 0.020) and stretching exercises (OR: 1.784, 95% CI: 1.104 to 2.883, p = 0.018). The independent predictors that significantly increased the severity of ODI included married marital status (p = 0.007), back surgery (p = 0.031), and higher pain intensity (p < 0.001).

CONCLUSIONS

We found that the prevalence rate of LBP among our sample was around 26%. This rate is approximate to the rates reported in previous studies. Furthermore, the activities most affected by LBP were sitting, standing, and lifting. Future studies should explore other risk factors and attempt to determine the onset of pain. A longitudinal study design is recommended to identify the onset of developing LBP.

Prevalence of Low Back Pain and Associated Factors Among Qassim University Medical Students: A Cross-Sectional Study

Introduction Low back pain (LBP) is a widespread and incapacitating issue that impacts a considerable portion of the adult population. Medical students, physicians, and other healthcare professionals have a high incidence of LBP. This study aimed to determine the prevalence and associated factors of LBP among medical students at two medical colleges in the Kingdom of Saudi Arabia. Methods Participants in this online cross-sectional study were medical students in two medical colleges at Qassim University in the Kingdom of Saudi Arabia. A questionnaire and the Oswestry Disability Index were sent through a social media platform. SPSS was used to analyze the data with a significance level of p < 0.05. Results The data of 350 medical school students were evaluated. Most participants were males (n = 180, 51.4%), 21 to 23 years old (n = 190, 54.3%), first-year medical students (n = 108, 30.9%), and in the basic medical education phase (n = 228, 65.3%). LBP prevalence was 82%. We found that 72.6% (n = 254) of participants did not exercise or participate in outdoor sports. More than half of the participants reported using a computer or laptop for fewer than eight hours per day. LBP was significantly associated with BMI (F = 3.457, p = 0.017) and computer use duration (T = 3.695, p < 0.001). LBP was not significantly associated with age (F = 0.892, p = 0.411) or gender (T = 1.566, p = 0.118). More than 90% (n = 323) of students had no disability per the Oswestry Disability Index. Conclusion LBP was highly prevalent among medical students and more prevalent among females, though gender and LBP were not associated. LBP was associated with high BMI and prolonged computer usage. Stakeholders should work to raise students' awareness of LBP and methods to improve their lifestyles and behaviors.

The Prevalence of Low Back Pain Among Medical Students: A Cross-Sectional Study From Saudi Arabia

BACKGROUND

Low back pain is a prevalent and debilitating condition that affects a significant proportion of the adult population. Medical students are particularly vulnerable due to the demands of their rigorous curriculum. Therefore, this study aims to investigate the prevalence and risk factors associated with low back pain among medical students.

METHODS

A cross-sectional survey was conducted among medical students and interns at King Faisal University in Saudi Arabia using a convenience sampling technique. An online questionnaire was distributed via social media applications to explore the prevalence and risk factors for low back pain.

RESULTS

Out of 300 medical students who participated in the study, 94% reported experiencing low back pain, with a mean pain score of 3.91 ± 2.0 out of 10. The most common factor that aggravated the pain was prolonged sitting. Logistic regression analysis revealed that sitting for more than eight hours (OR=5.61; 95% CI: 2.92-21.42) and not engaging in physical exercise (OR=3.10; 95% CI: 1.34-6.57) were independently associated with a higher prevalence of low back pain. These findings highlight the increased risk of low back pain among medical students due to prolonged sitting and a lack of physical activity.

CONCLUSION

This study provides evidence of the high prevalence of low back pain among medical students and identifies significant risk factors that exacerbate the condition. It emphasizes the need for targeted interventions to promote physical activity, reduce prolonged sitting, manage stress, and encourage good posture among medical students. The implementation of such interventions could help alleviate the burden of low back pain and improve the quality of life for medical students.

The association between different physical activity levels and flexion-relaxation phenomenon in women: a cross-sectional study

BACKGROUND

To investigate whether the flexion-relaxation phenomenon differs in women with different physical activity levels.

METHODS

Seventy-two subjects were recruited for this study. The electromyographic activity of the erector spinae and multifidus muscles was recorded during a flexion task using a surface electromyographic device. The flexion-relaxation and extension-relaxation ratios were calculated. Participants were classified into different physical activity level groups based on their responses to the International Physical Activity Questionnaire. A Welch analysis of variance was conducted to compare the flexion-relaxation ratio and extension-relaxation ratio between groups.

RESULTS

A significant difference in the flexion-relaxation and extension-relaxation ratio was observed in both the erector spinae and multifidus muscles between different levels of physical activity.

CONCLUSIONS

In this study, we observed that female participants with high levels of physical activity showed a more pronounced flexion-relaxation phenomenon compared to those with moderate and low levels of physical activity. No significant difference was found between moderate and low physical activity levels. The findings of our study highlight the association between physical activity and the mechanics of the spinal stabilising muscles.

Preliminary investigation of the effects of sitting with and without short active breaks on muscle stiffness assessed with shear-wave elastography

Purpose

The purpose of this preliminary study was to compare the effects of 1-h sitting with and without short active breaks on muscle stiffness as measured by shear-wave elastography (SWE).

Methods

The participants (7 females, 3 males; age: 24.9 ± 1.2 years) completed two (with and without active breaks) 1-h sitting exposures on separate days. Active breaks (2–3 min) were performed at 20 min and 40 min time marks and comprised simple stretching and activation exercises. Before, during (30 min) and after (1 h) of sitting, shear modulus of upper trapezius, lumbar region of erector spinae and rectus femoris muscles was measured with SWE.

Results

Statistically significant effects of sitting exposure in erector spinae muscle stiffness were noted (p = 0.041; η2 = 0.38). There were no other statistically significant effects of sitting exposure or condition (with/without breaks).

Conclusions

Although few statistically significant effects were detected, the trends in this preliminary trial suggest that prolonged sitting increases muscle stiffness and warrants further investigation of short active breaks with larger sample sizes.

The occurrence of flexion-relaxation phenomenon in elite cyclists during trunk forward bending

Flexion-relaxation phenomenon (FRP) is a well-known phenomenon in spinal extensor muscles. According to the literature, prolonged flexed posture leads to creep phenomenon and affects the active and passive neuromuscular control of the spinal column. The purpose of this study was to investigate FRP occurrence in elite cyclists that prolonged flexion posture is an integral part of their professional life. Their muscles' contraction pattern during forward bending was also compared. Electromyography (EMG) was recorded during flexion and extension from standing position in thoracic erector spinae (TES), lumbar erector spinae (LES) and gluteus maximus (Gluteus max) in 15 healthy male elite cyclists. In addition, the kinematic data related to the trunk angles were simultaneously recorded by a motion analysis system. Two-way ANOVA was used to assess the effects of muscle group and direction of movement on maximum amplitude of EMG activity. Among 15 cyclists, FRP was detectable in 60%, 87% and 73% of the participants in TES, LES and Gluteus max, respectively, and happened between 74% and 82% of the trunk flexion. There was no statistically significant difference in onset and offset of muscles FRP. Despite prolong hyper kyphotic posture, FRP was identifiable in TES, LES and Gluteus max muscles of elite cyclists.

The Effects of Standing Working Posture on Operation Force and Upper Limb Muscle Activation When Using Different Pointing Devices

This study investigated how sitting and standing working postures affected operation force, upper limb muscle activation, and task performance using different pointing devices. Fifteen male participants completed cursor aiming and dragging tasks using a conventional mouse, a vertical mouse, and a trackball at sitting and standing workstations. A custom-made force plate was used to measure operation forces applied to the pointing devices. Surface electromyography (EMG) was used to capture the activation of the biceps brachii, triceps brachii, deltoid, and trapezius. Task performance was measured by task success rates, and subjective ratings were obtained for the force required for operation, smoothness of operation, accuracy, and local fatigue in the upper limb. We quantified the following significant outcomes: (1) greater operation forces were found when standing; (2) standing reduced EMG amplitudes of the triceps and trapezius muscles for all tasks; (3) during the aiming task, the vertical mouse had greater operation forces; (4) during the dragging task, both the vertical mouse and trackball had greater operation forces; and (5) task success rates differed for pointing devices only when sitting. This study revealed the distinct biomechanical properties of standing working posture and suggested limited beneficial effects of alternative pointing devices in terms of task performance and subjective ratings.

The Effect of Standing Mats on Biomechanical Characteristics of Lower Limbs and Perceived Exertion for Healthy Individuals during Prolonged Standing

Objective

To identify the effect of standing mats on biomechanical characteristics of lower limbs and perceived exertion for healthy adult individuals during a prolonged standing task.

Methods

32 healthy college students were recruited in the randomized and cross-over designed trial according to the effect size and statistical power. After collecting the anthropometric data, each participant was asked to finish 2 sessions of 4-hour prolonged standing tasks on standing mats (MS) and hard ground (GS) in a random order and with a 72-hour interval rest. The plantar pressure distribution, foot morphology, and scores of the BESS (balance error scoring system) would be recorded pre- and posteach task. The Borg Rating of Perceived Exertion (RPE) would be collected during the whole task. Paired-samples t test was adopted to analyse the before and after difference within group and independent-samples t test was adopted to analyse the difference between groups separately.

Results

(1) A prolonged standing task on both MS and GS have a negative effect on RPE and balance performance. (2) The negative effect on RPE and balance performance induced by MS is significantly smaller than that induced by GS. (3) Compared to GS, prolonged standing on MS has a lower peak plantar pressure and an implicit decrease in navicular drop and AHI (arch index).

Conclusion

Standing mat tends to alleviate the fatigue induced by prolonged standing in lower limbs, optimize the distribution of plantar pressure, and maintain the stability.

Use of an inflatable mat to reduce body discomfort development when performing computer work at a standing desk

This study aimed to determine the effects of inflatable mat design on body discomfort, task performance, and musculoskeletal exposures during standing computer work. Twenty-seven healthy adults completed three 2-hour standing trials on different mediums (concrete floor, foam mat, and inflatable mat) on different days in an experimental laboratory. Both mats were associated with reduced discomfort in all lower-body regions and increased typing performance compared to the concrete floor. Perceived discomfort in lower extremities (except thighs) was further alleviated while standing on the inflatable mat than on the foam mat. Use of the inflatable mat led to increased lower-body muscle activity, a flexed lower back, and a wide range of sagittal knee movements. As standing time increased, body discomfort increased, typing accuracy decreased, and there were increased variations in muscle activity and postural movements in the lower body. The inflatable mat shows potential to improve the ergonomic experience during prolonged standing. Practitioner summary: Incorporating standing postures in office-based workplaces can reduce sitting time and may mitigate the health hazards associated with sedentary behaviour. With adequate weight-shifting movements, using an inflatable mat for standing could be an effective way to lessen discomfort and accumulated musculoskeletal strain due to constrained standing, without jeopardising task productivity. Abbreviations: APDF: amplitude probability distribution function. AVR: average rectified value. CI: confidence interval. CMRR: common mode rejection ratio. COP: center of pressure. CV: coefficient of variation. EA: electrical activity. EMG: electromyography. FL: fibularis longus. GM: gluteus medius. LBP: lower back pain. LES: lumbar erector spinae. MVC: maximum voluntary contraction. PD: pain developer. rANOVA: repeated-measures analysis of variance. SOL: soleus. VAS: visual analog scale. WPM: words per minute.

Musculoskeletal pain and sedentary behaviour in occupational and non-occupational settings: a systematic review with meta-analysis

BACKGROUND

Sedentary behaviour (SB; time spent sitting) is associated with musculoskeletal pain (MSP) conditions; however, no prior systematic review has examined these associations according to SB domains. We synthesised evidence on occupational and non-occupational SB and MSP conditions.

METHODS

Guided by a PRISMA protocol, eight databases (MEDLINE, CINAHL, PsycINFO, Web of Science, Scopus, Cochrane Library, SPORTDiscus, and AMED) and three grey literature sources (Google Scholar, WorldChat, and Trove) were searched (January 1, 2000, to March 17, 2021) for original quantitative studies of adults ≥ 18 years. Clinical-condition studies were excluded. Studies' risk of bias was assessed using the QualSyst checklist. For meta-analyses, random effect inverse-variance pooled effect size was estimated; otherwise, best-evidence synthesis was used for narrative review.

RESULTS

Of 178 potentially-eligible studies, 79 were included [24 general population; 55 occupational (incuding15 experimental/intervention)]; 56 studies were of high quality, with scores > 0.75. Data for 26 were meta-synthesised. For cross-sectional studies of non-occupational SB, meta-analysis showed full-day SB to be associated with low back pain [LBP - OR = 1.19(1.03 - 1.38)]. Narrative synthesis found full-day SB associations with knee pain, arthritis, and general MSP, but the evidence was insufficient on associations with neck/shoulder pain, hip pain, and upper extremities pain. Evidence of prospective associations of full-day SB with MSP conditions was insufficient. Also, there was insufficient evidence on both cross-sectional and prospective associations between leisure-time SB and MSP conditions. For occupational SB, cross-sectional studies meta-analysed indicated associations of self-reported workplace sitting with LBP [OR = 1.47(1.12 - 1.92)] and neck/shoulder pain [OR = 1.73(1.46 - 2.03)], but not with extremities pain [OR = 1.17(0.65 - 2.11)]. Best-evidence synthesis identified inconsistent findings on cross-sectional association and a probable negative prospective association of device-measured workplace sitting with LBP-intensity in tradespeople. There was cross-sectional evidence on the association of computer time with neck/shoulder pain, but insufficient evidence for LBP and general MSP. Experimental/intervention evidence indicated reduced LBP, neck/shoulder pain, and general MSP with reducing workplace sitting.

CONCLUSIONS

We found cross-sectional associations of occupational and non-occupational SB with MSP conditions, with occupational SB associations being occupation dependent, however, reverse causality bias cannot be ruled out. While prospective evidence was inconclusive, reducing workplace sitting was associated with reduced MSP conditions. Future studies should emphasise prospective analyses and examining potential interactions with chronic diseases.

PROTOCOL REGISTRATION

PROSPERO ID # CRD42020166412 (Amended to limit the scope).

Effects on variation in shoulder, forearm and low back muscle activity from combining seated computer work with other productive office tasks: results from a simulation study

The effect on muscle activity variation of combining different office tasks is not known. We recorded electromyography from the upper trapezius (UT), wrist extensor (WE) and lumbar erector spinae (LES) in 24 office workers during five productive tasks, and breaks. Minute-to-minute variance was then estimated, by simulations, in a reference 'job' consisting of 85% sitting computer work and 15% breaks, and in 'jobs' where sitting computer work was replaced by different proportions of the other office tasks and breaks. Replacing sitting computer work with sitting non-computer work increased estimated variance by, in median, 23% (UT), 19% (WE) and 0% (LES). Replacing it with other tasks, in particular, standing computer and non-computer work, was less effective in increasing variance. Thus, some combinations of office tasks have a slight potential to increase muscle activity variation in the shoulder and lower arm, but not the lumbar back, while others will be ineffective. Practitioner summary: The need for exposure variation is often emphasised in office ergonomics. We estimated the effect on muscle activity in the shoulder, forearm and lumbar back of combining sitting computer work with other available tasks and breaks, finding that introduction of sitting non-computer tasks and non-desk work slightly increased variation; other tasks were essentially non-effective.