Work environment and low back pain: the influence of occupational activities

Age-dependent flexion relaxation phenomenon in chronic low back pain patients

Background

The flexion relaxation phenomenon (FRP) is characterized by suddenly reduced paraspinal muscle activity during full flexion. Previous studies showed significant differences in FRP and flexion angles in chronic low back pain (cLBP) patients compared to individuals without back pain (no-BP). However, the relationship between FRP and flexion angles remains insufficiently understood in older populations. Thus, this study investigated the relationship between FRP and flexion angles concerning to the age and presence of cLBP.

Methods

Forty no-BP subjects (20m/20f; mean age 41.5 years) and thirty-eight cLBP patients (19m/19f; mean age 43.52 years) performed maximum full upper body flexion task. Electromyographic (EMG) measurements were conducted to assess the activity of lumbar erector spinae (ESL), thoracic erector spinae (EST), and multifidus (MF). Lumbar, thoracic, and pelvic angles at the onset (OnsetL/T/P) and offset of the FRP (OffsetL/T/P) and maximum trunk inclination (MaxL/T/P) were calculated. The FRP was evaluated using a flexion relaxation ratio (FRR).

Results

cLBP patients showed smaller FRR in MF and right ESL compared to no-BP individuals (p < 0.05), while no differences were found in flexion angles between two groups. Subjects over 40 showed smaller FRR in MF and ESL, and smaller flexion angles on OffsetL and MaxL (p < 0.05). Age-related analysis in the cLBP group revealed that patients over 40, compared to younger ones, had smaller FRR in MF and ESL, and smaller values in all thoracic and lumbar flexion angles (p < 0.05). While in no-BP group, significant larger flexion angles in OnsetL and OffsetT (p < 0.05) were observed in participants over 40. Pain-related analysis in the older group revealed that the cLBP patients, compared to no-BP individuals, had smaller FRR in right MF and right ESL, and smaller values in all lumbar and thoracic flexion angles (p < 0.05), while in younger group, there were no significant pain-related differences in FRR, with larger values in all lumbar flexion angles (p < 0.05).

Conclusion

Our findings indicate a reduction or absence of FRP in cLBP patients compared to no-BP individuals, with age being a significant factor as those over 40 showed smaller FRP and flexion angles compared to younger individuals.

Aetiological Factors of Running-Related Injuries: A 12 Month Prospective "Running Injury Surveillance Centre" (RISC) Study

BACKGROUND

Running-related injuries (RRIs) are a prevalent issue for runners, with several factors proposed to be causative. The majority of studies to date are limited by retrospective study design, small sample sizes and seem to focus on individual risk factors in isolation. This study aims to investigate the multifactorial contribution of risk factors to prospective RRIs.

METHODS

Recreational runners (n = 258) participated in the study, where injury history and training practices, impact acceleration, and running kinematics were assessed at a baseline testing session. Prospective injuries were tracked for one year. Univariate and multivariate Cox regression was performed in the analysis.

RESULTS

A total of 51% of runners sustained a prospective injury, with the calf most commonly affected. Univariate analysis found previous history of injury < 1 year ago, training for a marathon, frequent changing of shoes (every 0-3 months), and running technique (non-rearfoot strike pattern, less knee valgus, greater knee rotation) to be significantly associated with injury. The multivariate analysis revealed previous injury, training for a marathon, less knee valgus, and greater thorax drop to the contralateral side to be risk factors for injury.

CONCLUSION

This study found several factors to be potentially causative of injury. With the omission of previous injury history, the risk factors (footwear, marathon training and running kinematics) identified in this study may be easily modifiable, and therefore could inform injury prevention strategies. This is the first study to find foot strike pattern and trunk kinematics to relate to prospective injury.

A survey of physical and occupational therapists' views on lumbar loading movements

[Purpose] To identify the lumbar loading movements necessary in clinical practice. [Participants and Methods] A questionnaire survey was conducted among physical and occupational therapists in Japan. There were no exclusion criteria regarding the number of years of experience, age, or field of employment. The participants were randomly selected and administered the questionnaire. They were asked to list and rank the lumbar loadings they considered necessary. [Results] A total of 739 respondents participated in the survey. The results of this nationwide survey indicated that the lifting movement of heavy objects in the trunk flexion position was the most common movement (for 354 participants). [Conclusion] The main loading movements of the lumbar spine were reported to be heavy lifting movements (in the trunk flexion position) and trunk rotation movements. As perspectives, we aim to conduct an analytical study of some of lumbar spine loading movements outlined in this study, using a musculoskeletal simulator and electromyography.

The association between sedentary behavior and low back pain in adults: a systematic review and meta-analysis of longitudinal studies

Background

Low back pain (LBP) is a common musculoskeletal problem globally. While spending a longer time in sedentary behaviors is linked to several health problems; the quantitative association between different amounts of sedentary time and LBP is still unknown. This study aims to systematically review studies that examined the association between sedentary behavior and LBP development and LBP-related outcomes.

Methods

This systematic review and meta-analysis retrieved journal articles published from inception to March 2020 and were obtained by searching bibliographical databases. We included longitudinal study designs, including adult (aged ≥18) individuals with nonspecific LBP, and reporting estimates of the association between sedentary behavior and LBP development and LBP-related outcomes (i.e., pain intensity and disability).

Results

Sixteen longitudinal studies with 100,002 participants were included in this review (eight studies included in quantitative syntheses with 83,111 participants). The results of meta-analyses showed that a sedentary time of 3-<6 (Odds ratio (OR) 0.95, 95% CI [0.85-1.07]), 6-8 (OR 0.95, 95% CI [0.88-1.02]), and >8 (OR 0.92, 95% CI [0.85-1.00]) hours per day (h/d) was not associated with LBP development. A sedentary time of ≥3 h/d was associated with poor LBP-related disability (OR 1.24, 95% CI [1.02-1.51]), but not with pain intensity.

Conclusion

A meta-analyses of longitudinal studies indicated that sedentary behavior of different durations was not associated with LBP development. However, the results showed that sedentary behavior ≥3 h/d was associated with worse LBP-related disability. These conclusions are tentative as the evidence was derived from mostly fair-quality studies using subjective measures of sedentary behavior.

Systematic review registration

PROSPERO (registration number CRD42018107078).

The Strategy of Workforce Management Based on Risk Assessment of Manual Handling Work with Suitability of Work Environment in Makasar Industrial Area, Indonesia

BACKGROUND: A good work environment suitability has a major impact on health and safety, and it encourages a more productive workforce. When it is incompatible with labor, it can lead to unintended impacts and various risks. AIM: We aimed to investigate the strategy of workforce management based on risk assessment of manual handling work with suitability of work environment in Makasar industrial area, Indonesia. METHODS: Twenty three workforce samples are selected from Makassar Industrial Area (KIMA), Indonesia. The risk of manual handling work is assessed based on the suitability of the work environment to the workforce’s response using Guttman scale, in which the answer YES = 1 means there is a risk, while the answer NO = 0 means there is no risk. However, the scales are the reproducibility coefficient ≥ 0.90 and scalability coefficient ≥0.60, and Guttman scale score is calculated from Tn = total answers of “YES” for the KPI in the scale. Meanwhile, the SWOT-4Q is used to analyze the strategy of industry supervisor samples. RESULTS: For the workforce, eight of nine risk assessments do not show risk, and only “high vibration intensity in the workplace,” with a percentage of 78.26%, affects the excessive condition. The strategy used by the supervisors in quadrant I is in accordance with the strength of the risk assessment and has a great opportunity to reduce risk. The management maximally exploits the big opportunity of the manual handling work. CONCLUSIONS: The results showed that most of the workforce did not experience the risk of manual handling work with the suitability of the work environment. In addition, industrial supervisors should implement a growth strategy because they can enlarge the industry by taking advantage of the advantages of manual handling work to maximize the exploitation of large manual handling work opportunities.

A Scoping Review on the Epidemiology of Chronic Low Back Pain among Adults in Sub-Saharan Africa

BACKGROUND

The global burden of chronic low back pain (CLBP) is a major concern in public health. Several CLBP epidemiological studies have been conducted in high-income-countries (HICs) with little known in low-and-middle-income-countries (LMICs) due to other competing priorities of communicable diseases. The extrapolation of results of studies from HICs for use in LMICs is difficult due to differences in social norms, healthcare systems, and legislations, yet there is urgent need to address this growing burden. It is against this backdrop that we conducted this review to map the current evidence on the distribution of CLBP in Sub-Saharan Africa (SSA).

METHODS

A comprehensive literature search was conducted from the following databases: PubMed, Google Scholar, Science Direct databases, World Health Organizations library databases, EMBASE, EBSCOhost by searching the following databases within the platform; academic search complete, CINAHL with full text, health sources: nursing/academic and MEDLINE. The title, abstract and the full text screening phases were performed by two independent reviewers with the third reviewer employed to adjudicate discrepancies. The reference list of all included articles was also searched for eligible articles. This scoping review was reported in accordance with the PRISMA extension for scoping reviews (PRISMA-ScR): checklist and explanation, as well as guided by Arksey and O'Malley's scoping review framework. A thematic content analysis was used to give a narrative account of the review.

RESULTS

The electronic search strategy retrieved 21,189 articles. Title/abstract and full text screening only identified 11 articles, which were included in this review. The prevalence of CLBP among the general population ranged from 18.1% to 28.2% and from 22.2% to 59.1% among LBP patients. The prevalence of occupation based CLBP ranged from 30.1% to 55.5%. Identified risk factors for CLBP are multifactorial and included biomechanical, psychological, socioeconomic and lifestyle factors, with psychosocial factors playing a significant role. Hypertension, diabetes mellitus, peptic ulcer disease were the most common comorbidities identified. CLBP disability was significantly associated with psychosocial factors. The management of CLBP in primary care follows the traditional biomedical paradigm and primarily involves pain medication and inconsistent with guidelines.

CONCLUSIONS

There are limited epidemiological data on CLBP in SSA, however, this study concluded that the prevalence and risk factors of CLBP in SSA are comparable to reports in HICs. Considering the projected increase in the burden of CLBP in LMICs extensive research effort is needed to close this knowledge gap.

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

Sit-stand desks continue to be a popular intervention for office work. While previous studies have reported changes in subjective measures, there is limited understanding of how sit-stand work differs from prolonged sitting or standing work, from a biomechanical standpoint. The objective of this study was to investigate the effects of prolonged sitting, prolonged standing, and a sit-stand paradigm on changes in trunk stiffness, low back discomfort, and trunk muscle activation. Twelve healthy participants performed 2 h of computer-based tasks in each protocol, on three different days. The sit-stand protocol was associated with a significant increase in trunk stiffness and a decrease in muscle activation of lumbar multifidus and longissimus thoracis pars thoracis, compared to both prolonged sitting and standing. Both sitting and standing were associated with increased low back discomfort. These findings may be worth exploring in more detail, for why alternating sit-stand patterns may help alleviate low back pain. Practitioner summary: We explored changes in objective and subjective measures related to low back discomfort following prolonged sitting, standing, and alternating sit-stand patterns. Alternating sit-stand pattern was associated with increased trunk stiffness and decreased back muscle activity. Hence, sit-stand desks may have benefits in terms of preventing/mitigating low back pain. Abbreviations: DOF: degree of freedom; EMG: electromyogram; ILL: iliocostalis lumborum pars lumborum; LTL: longissimus thoracis pars lumborum; LTT: longissimus thoracis pars thoracis; LBP: low back pain; LM: lumbar multifidus; MVEs: maximum isometric voluntary exertions; RANOVA: repeated-measure analysis of variance; RMS: root mean square.

Lifestyle and subjective musculoskeletal symptoms in young male Japanese workers: A 16-year retrospective cohort study

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The SN/S and LBP risk was higher in the PL than in the GL group.

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Four positive predictors (life satisfaction, hours of sleep, exercise habits, physical fitness) are important factors.

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Health staff should advise on workers’ individual lifestyle.

This longitudinal study was conducted from 2002 to 2018 and aimed to investigate predictive lifestyle factors for the occurrence of subjective musculoskeletal symptoms. The participants came from several employers in Japan. Setting 2002 as the baseline, we performed logistic regression analyses using lifestyle questionnaire items as explanatory variables and Stiff neck/shoulders (SN/S) and Lower back pain (LBP) as objective variables (n = 16,748). Workers who responded positively to good lifestyle items with an odds ratio < 1.0 and those who did not were classified in the Good (GL) and Poor lifestyle groups (PL), respectively. The survival period between the groups was compared using the log-rank test and Cox hazard regression analysis with propensity score matching (n = 3,593). Based on the Cox hazard regression analysis results, the risk of SN/S was about 2.54 (95% confidence interval [CI]: 1.80–3.59) times higher for PL than for GL (p < 0.001). Similarly, after propensity score matching, the risk was about 2.33 (95% CI: 1.07–5.10) times higher for PL than for GL (p < 0.05). Further, LBP risk was about 2.45 (95% CI: 1.67–3.58) times higher for PL than for GL (p < 0.001). Similarly, after propensity score matching, the risk was about 3.50 (95% CI: 1.60–7.68) times higher for PL than for GL (p < 0.01). This study highlighted that workers with four good lifestyle factors (life satisfaction, hours of sleep, exercise habits, and physical fitness) presented reduced risk of subjective musculoskeletal symptom occurrence. To prevent musculoskeletal symptoms, physicians and occupational health staff should advise on workers’ individual lifestyle.

Development and evaluation of RAMP II - a practitioner's tool for assessing musculoskeletal disorder risk factors in industrial manual handling

RAMP II is an observation-based tool developed for assessing a wide range of musculoskeletal disorder risk factors related to industrial manual handling. RAMP II, which is part of the RAMP tool, is based on research studies and expert judgments. The assessment relies mainly on direct or video observations of the work being assessed, but additionally on measured push/pull forces and weights of handled objects, and on perceived workload and discomfort. Over 80 practitioners participated in the development of the tool. According to the evaluations, 73% of the assessment items evaluated had acceptable reliability, and the majority of the potential end-users reported that RAMP II is usable for assessing risks and as a decision base. It is concluded that this study provides support that RAMP II is usable for risk assessment of musculoskeletal disorder risk factors in industrial manual handling. Practitioner summary: RAMP II is an observation-based assessment tool for screening and assessing major musculoskeletal exposures in industrial manual handling jobs. Over 80 practitioners participated in the development of the tool. This study provides support that RAMP II is usable for risk assessment of musculoskeletal disorder risk factors in industrial manual handling. Abbreviations: CTS: carpal tunnel syndrome; HARM: the Hand Arm Risk Assessment method; IMP: intramuscular pressure; κ_w: linearly weighted kappa; LBD: lower back disorders; LBP: lower back pain; MAWL: maximum acceptable weight of lift; MHO: manual handling operations; MSD: musculoskeletal disorder; MNSD: neck-shoulder disorder; NSP: neck-shoulder pain; OCRA: the Occupational Repetitive Action methods; OHS: occupational health and safety; PABAK: prevalence and bias adjusted kappa; p₀: proportion of agreement; RAMP: Risk Assessment and Management tool for manual handling Proactively; ROM: range of motion; RPL: risk and priority level; RSI: the Revised Strain Index; RULA: the Rapid Upper Limb Assessment; SWEA: Swedish Work Environment Authority; UEMSDs: upper-extremity work-related musculoskeletal disorders; WMSD: work-related musculoskeletal disorder; WRMSD: work-related musculoskeletal disorder; workday_8h: eight hours workday.

Chronic Musculoskeletal Pain, Self-Reported Health and Quality of Life among Older Populations in South Africa and Uganda

Chronic musculoskeletal pain (CMP) is a serious health concern especially among the elderly population and has significant bearing on health and quality of life. Not much is known about the relationship between chronic pain with self-reported health and quality of life among older populations in low-resource settings. Based on sub-national data from South Africa and Uganda, the present study aimed to explore whether the older population living with CMP report health and quality of life differently compared to those with no CMP complaints. This study was based on cross-sectional data on 1495 South African and Ugandan men and women collected from the SAGE Well-Being of Older People Study. Outcome variables were self-reported physical and mental health and quality of life (QoL). Mental health was assessed by self-reported depressive symptoms during the last 12 months. CMP was assessed by self-reported generalised pain as well as back pain. Multivariable logistic regression models were used to measure the association between health and QoL with CMP by adjusting for potential demographic and environmental confounders. The prevalence of poor self-rated health (61.2%, 95% CI = 51.7, 70.0), depression (37.2%, 95% CI = 34.8, 39.6) and QoL (80.5%, 95% CI = 70.8, 87.5) was considerably high in the study population. Mild/moderate and Severe/extreme generalised pain were reported respectively by 34.5% (95% CI = 28.9, 40.5) and 15.7% (95% CI = 12.2, 19.9) of the respondents, while back pain was reported by 53.3% (95% CI = 45.8, 60.4). The prevalence of both types was significantly higher among women than in men (p < 0.001). In the multivariate analysis, both generalised pain and back pain significantly predicted poor health, depression and QoL, however, it varied between the two different populations. Back pain was associated with higher odds of poor self-rated health [OR = 1.813, 95% CI = 1.308, 2.512], depression [1.640, 95% CI = 1.425, 3.964] and poor QoL [1.505, 95% CI = 1.028, 2.202] in South Africa, but not in Uganda. Compared to having no generalised pain, having Mild/Moderate [OR = 2.309, 95% CI = 1.219, 7.438] and Severe/Extreme [OR = 2.271, 95% CI = 1.447, 4.143] generalised pain was associated with significantly higher odds of poor self-rated health in South Africa. An overwhelmingly high proportion of the sample population reported poor health, quality of life and depression. Among older individuals, health interventions that address CMP may help promote subjective health and quality and life and improve psychological health.

Back muscle activity and sagittal spinal alignment during quadruped upper and lower extremity lift in young men with low back pain history

BACKGROUND

Quadruped upper and lower extremity lift (QULEL) is performed for selective training of the lumbar multifidus muscle in patients with low back pain (LBP) or individuals with LBP history (LBPH). However, the activities of the back muscles and sagittal spinal alignment during QULEL are not clarified in individuals with LBPH.

RESEARCH QUESTION

This study aimed to analyze the activities of the back muscles and sagittal spinal alignment during QULEL in young male with LBPH.

METHODS

The study comprised 9 asymptomatic young men and 8 young men with LBPH. The activities of the lumbar multifidus, latissimus dorsi and thoracic erector spinae, and lumbar erector spinae muscles were measured using surface electromyography. The flexion angles of the upper and lower thoracic spine, and extension angle of the lumbar spine were measured using a 6-DF electromagnetic motion tracking system. The association with LBPH was investigated using multiple logistic regression analysis with a forward selection method, with the activities of the back muscles, sagittal spinal alignment, age, body height, and body weight as independent variables.

RESULTS

Multiple logistic regression analysis (p = 0.0002) showed that the activity of the latissimus dorsi and thoracic erector spinae muscles in the side on which the lower extremity was lifted and body height were significant and independent determinants of LBPH, but other factors were not.

SIGNIFICANCE

The results of this study suggest that the activity of the latissimus dorsi and thoracic erector spinae muscles increases while there are no decrease in activity of the lumbar multifidus muscle and excessive extension of the lumbar spine during QULEL in young men with LBPH.

Effect of Using a Sit-Stand Desk on Ratings of Discomfort, Fatigue, and Sleepiness Across a Simulated Workday in Overweight and Obese Adults

BACKGROUND

Limited research examines the influence of sit-stand desks on ratings of discomfort, sleepiness, and fatigue. This study evaluated the time course of these outcomes over 1 day.

METHODS

Adults (N = 25) completed a randomized cross-over study in a laboratory with two 8-hour workday conditions: (1) prolonged sitting (SIT) and (2) alternating sitting and standing every 30 minutes (SIT-STAND). Sleepiness was assessed hourly. Discomfort, physical fatigue, and mental fatigue were measured every other hour. Linear mixed models evaluated whether these measures differed across conditions and the workday. Effect sizes were calculated using Cohen's d.

RESULTS

Participants were primarily white (84%) males (64%), with mean (SD) body mass index of 31.9 (5.0) kg/m² and age 42 (12) years. SIT-STAND resulted in decreased odds of discomfort (OR = 0.37, P = .01) and lower overall discomfort (β = -0.19, P < .001, d = 0.42) versus SIT. Discomfort during SIT-STAND was lower in the lower and upper back, but higher in the legs (all Ps< .01, d = 0.26-0.42). Sleepiness (β = -0.09, P = .01, d = 0.15) and physical fatigue (β = -0.34, P = .002, d = 0.34) were significantly lower in SIT-STAND. Mental fatigue was similar across conditions.

CONCLUSIONS

Sit-stand desks may reduce acute levels of sleepiness, physical fatigue, and both overall and back discomfort. However, levels of lower extremity discomfort may be increased with acute exposure.

Evaluation of vibrant muscles over the shoulder region among workers of the hand screen printing industry

This study focuses on evaluation of the muscle activities associated with shoulder pain among workers of the hand screen printing (HSP) industry. Activities of three major muscles which showed higher muscle activity for a HSP job were observed for fatigue using surface electromyography (SEMG). The anatomical sites were chosen on the basis of a statistical survey and a visual inspection conducted before the experiment. Activities of the deltoid, teres major and infraspinatus were recorded using SEMG and the nature of muscle activities was studied for about 50 m of cloth printing. Data collected were processed using LabVIEW 2014 and the activities were analyzed using statistical tests and regression analyses. The results showed an increased risk of shoulder disorders with an increase in working time. Some of the risks which might cause disorders were predicted from the results; inspection and possible mitigations were suggested.

Hip Abductor Fatigability and Recovery Are Related to the Development of Low Back Pain During Prolonged Standing

A prolonged standing exposure can identify asymptomatic adults who have a higher risk of developing clinical low back pain later in life. Hip abductor cocontraction differences can predict low back pain development during standing exposures. This study’s purpose was to determine if hip abductor strength, fatigability, and recovery during prolonged standing were related to standing-induced low back pain. Forty young, asymptomatic adults (50% female) performed two 2-hour standing sessions; a fatiguing hip abductor exercise was performed prior to 1 of the 2 standing sessions. Hip abductor strength and surface electromyography of gluteus medius and tensor fascia latae were measured. Self-reported low back pain differentiated low back pain developing (PD) and nonpain developing (NPD) groups. The PD group hip abductors fatigued before the NPD group, with similar perceived effort and force losses. Mean power frequency decreases with fatigue were similar between pain groups for all muscles measured after the fatiguing exercise. Unlike NPDs, PDs did not recover force losses after 120 minutes of standing. Hip abductor fatigability may be related to the development of low back pain in this population.

The effect of short duration low back vibration on pain developed during prolonged standing

The purpose of this study was to determine if vibration, a potential method of pain management, applied to the low back could alleviate pain developed during prolonged standing. Eighteen healthy individuals participated in a 2.5-h standing task during which vibration (3-min duration) was applied at the 2-h and 2.25-h marks. During the full 2.5 h, participants recorded their perceived pain scores every 15 min using a 10 cm visual analogue scale (VAS). Following each vibration bout, those who developed low back pain (LPB) reported statistically lower VAS scores compared to prior to the vibration; however, when the vibration ceased, LBP returned to pre-vibration levels. It appears that vibration may be an effective method of alleviating LBP caused by prolonged standing; however, the effects seem to be temporary. Further research is needed to investigate the optimal vibration frequency and time period to maximize pain management effectiveness.

Spasm and flexion-relaxation phenomenon response to large lifting load during the performance of a trunk flexion-extension exercise

BACKGROUND

The flexion relaxation phenomenon (FRP) has been widely investigated. Nevertheless, no study has been reported on the FRP as well as spasm response to large lifting load. The aim of this study was to evaluate the effect of large lifting load on the FRP response and spasm during execution of a flexion-extension exercise.

METHODS

Twenty-two healthy male university students without low back pain history participated this study. Subjects randomly performed three trials of trunk flexion-extension cycles of 5 s flexion and 5 s extension in each of 4 conditions (three large lifting loads of 15, 20 and 25 kg and one lifting load of 0 kg for comparison). Surface EMG from bilateral erector spinae was recorded during the performance of a trunk anterior flexion-extension exercise. The relaxation phase was determined through the onset of electromyography (EMG) signals. Spasm was evaluated in the relaxation period. The mean normalized electromyography (NEMG) was derived from the raw EMG.

RESULTS

Spasm was observed in more than 45% of the individuals and the intensity of muscle activation was increased by more than 78% in the relaxation phase.

CONCLUSIONS

A large lifting load could lead to a high prevalence of spasms as well as a high intensity of muscle activations on erector spinae muscle in the relaxation period, which may be associated with the development of low back disorder during the performance of a flexion-extension exercise.

Association of low back pain with muscle stiffness and muscle mass of the lumbar back muscles, and sagittal spinal alignment in young and middle-aged medical workers

BACKGROUND

Muscle stiffness of the lumbar back muscles in low back pain (LBP) patients has not been clearly elucidated because quantitative assessment of the stiffness of individual muscles was conventionally difficult. This study aimed to examine the association of LBP with muscle stiffness assessed using ultrasonic shear wave elastography (SWE) and muscle mass of the lumbar back muscle, and spinal alignment in young and middle-aged medical workers.

METHODS

The study comprised 23 asymptomatic medical workers [control (CTR) group] and 9 medical workers with LBP (LBP group). Muscle stiffness and mass of the lumbar back muscles (lumbar erector spinae, multifidus, and quadratus lumborum) in the prone position were measured using ultrasonic SWE. Sagittal spinal alignment in the standing and prone positions was measured using a Spinal Mouse. The association with LBP was investigated by multiple logistic regression analysis with a forward selection method. The analysis was conducted using the shear elastic modulus and muscle thickness of the lumbar back muscles, and spinal alignment, age, body height, body weight, and sex as independent variables.

FINDINGS

Multiple logistic regression analysis showed that muscle stiffness of the lumbar multifidus muscle and body height were significant and independent determinants of LBP, but that muscle mass and spinal alignment were not. Muscle stiffness of the lumbar multifidus muscle in the LBP group was significantly higher than that in the CTR group.

INTERPRETATION

The results of this study suggest that LBP is associated with muscle stiffness of the lumbar multifidus muscle in young and middle-aged medical workers.

Relative mobility of the pelvis and spine during trunk axial rotation in chronic low back pain patients: A case-control study

Background

Trunk axial rotation is a risk factor for chronic low back pain (CLBP). The characteristics of rotational mobility in the pelvis and spine among CLBP patients are not fully understood.

Purpose

The purpose of this study was to examine three-dimensional kinematic changes, and to compare the differences of rotational mobility and coupled motion, in patients with and without CLBP.

Methods

Fifteen patients with CLBP and 15 age and sex matched healthy subjects participated in this study. Each subject performed trunk rotation to maximum range of motion (ROM) in a standing position. The kinematics data was collected using a three-dimensional motion analysis system. The outcomes measured were the rotational ROM and the spine/pelvis ratio (SPR) in transvers plane at both maximum and 50% rotation position. The coupled angles in sagittal and frontal planes were also measured.

Results

No significant differences in rotational ROM of the thorax, pelvis, and spine were observed between two groups at maximum rotation position. However, there was a significant interaction between groups and rotational ROM of pelvis and spine (F = 4.57, p = 0.04), and the SPR in CLBP patients was significantly greater than that of the healthy subjects (CLBP; 0.50 ± 0.10 Control; 0.41 ± 0.12, p = 0.04). The results at 50% rotation position were similar to that at maximum rotation. This indicates a relative increase in spinal rotation in the CLBP patients during trunk rotation. Moreover, the CLBP patients exhibited a significantly higher anterior tilt of the pelvis and extension of the spine in the sagittal plane coupled with rotation.

Conclusions

CLBP patients had relative hyper rotational mobility of the spine as well as excessive spinal extension coupled with trunk rotation. These results suggest that uncoordinated trunk rotation might be a functional failure associated with CLBP.

Association Between Whole-Body Vibration and Low-Back Disorders in Farmers: A Scoping Review

INTRODUCTION

Low-back disorders (LBDs) are the most common musculoskeletal problem among farmers, with higher prevalence rates than in other occupations. Farmers who operate tractors and other types of machinery can have substantial exposure to whole-body vibration (WBV). Although there appears to be an association between LBDs and WBV, the causal relationship is not clear.

OBJECTIVE

This scoping review investigates the association between WBV and LBDs specifically among farmers.

METHODS

Nine databases were searched using groups of terms for two concepts: 'farming' and 'low back disorder'. Screening, data extraction, and quality assessment were performed by two reviewers independently. Included studies met the following criteria: focused on adult farmers/agricultural workers; assessed exposure to operating farm machinery such tractor, combine, or all-terrain vehicle; assessed LBDs as an outcome; and reported an inferential test to assess the relationship between WBV and LBD.

RESULTS

After 276 full texts screened, 11 articles were found to analyze WBV as a risk factor for LBDs. Three were case-control, five cross-sectional, and three retrospective cohorts. Four studies showed no association between WBV and LBDs, four a positive association, and three results were mixed depending on the exposure/outcome measure.

CONCLUSION

A firm conclusion is difficult due to heterogeneity in, LBDs definition, type of farm commodity, study design, and statistical strategy. Direct comparisons and synthesis were not possible. Although retrospective cohort studies tended to show a relationship, future studies with a prospective cohort design could help clarify this association further.

Are people with chronic low back pain meeting the physical activity guidelines? A co-twin control study

BACKGROUND

Despite a large amount of research investigating physical activity (PA) levels in people with chronic low back pain (LBP), no study has investigated whether people with chronic LBP are meeting the World Health Organization (WHO) PA guidelines. Furthermore, with genetics and the early shared environment substantially influencing the presence of LBP and PA engagement, these factors could confound the association between LBP and PA and need to be controlled for.

PURPOSE

This study aimed to investigate the association between chronic LBP and meeting the PA guidelines, while controlling for the effects of genetics and early shared environment.

DESIGN

This is a cross-sectional co-twin control study.

PATIENT SAMPLE

A cross-sectional analysis was performed on 1,588 twins from the Murcia Twin Registry in Spain with available data on LBP and PA from the 2013 data collection wave.

OUTCOME MEASURES

The exposure and outcome variables in our study were self-reported. Twins reporting a history of chronic LBP were asked follow-up questions to inform on the presence of recent LBP (within the past 4 weeks), previous LBP (no pain within the past 4 weeks), and persistent LBP (no pain-free month in the last 6 months). These were our exposure variables. Our outcome variable was meeting the WHO PA guidelines, which involved at least 75 minutes of vigorous-intensity PA, or at least 150 minutes of moderate-intensity PA per week.

METHODS

To investigate the association between chronic LBP and meeting the PA guidelines, we first performed a multivariate logistic regression on the total sample of twins. Co-variables entered the model if the univariate association between the co-variable, and both the exposure and the outcome reached a significance of p<.2. Second, to adjust for the influence of genetics and early shared environment, we performed a conditional multivariate logistic regression on complete twin pairs discordant for LBP. The Murcia Twin Registry is supported by Fundación Séneca, Regional Agency for Science and Technology, Murcia, Spain (08633/PHCS/08 and 15302/PHCS/10) and the Ministry of Science and Innovation, Spain (PSI11560-2009). Funding for this project has also been received from Fundación MAPFRE (2012). The authors declare that there are no conflicts of interest.

RESULTS

There was a significant inverse association between recent LBP and meeting the PA guidelines (odds ratio [OR]=0.71, p=.034). When controlling for genetics and early shared environment, this association disappeared. There was no association between previous (OR=0.95, p=.779) or persistent LBP (OR=0.78, p=.192) and meeting the PA guidelines.

CONCLUSION

Twins with recent LBP are less likely to meet the PA guidelines than those with no history of chronic LBP, highlighting the importance of incorporating PA promotion in the treatment of these individuals. Genetics and early shared environment appear to be confounding the association between LBP and PA, although this needs to be further tested in larger twin samples.

Activation of back and lower limb muscles during squat exercises with different trunk flexion

[Purpose] The purpose of this study was to investigate the activation of back and lower limb muscles in subjects who were performing a squat exercise at different angles of trunk flexion. [Subjects and Methods] Twenty healthy subjects (age 21.1± 1.8 years, height 168.7 ± 8.2 cm, weight 66.1 ± 12.3 kg) volunteered. The activation of the erector spinae muscle, rectus femoris muscle, gluteus maximus muscle and biceps femoris muscle was observed while the subjects performed squat exercises with a trunk flexion of 0°, 15°, and 30°. [Results] The erector spinae muscle, gluteus maximus muscle, and biceps femoris muscle were activated more during the squat exercise with the trunk flexion at 30° than the exercise with the trunk flexion at 0°. The rectus femoris muscle showed a tendency to decrease as the truck flexion increased. [Conclusion] Squat exercise be executed while maintaining an erect trunk posture if one wishes to strengthen the quadriceps muscle while reducing the load on the lower back.

Risk Profiles for Four Types of Work-Related Injury among Hospital Employees

In this retrospective case-control study, researchers examined risk factors for four types of work-related injury (WRI) in hospital employees. Data were collected from employee health charts and computer databases ( N = 2050) and analyzed using logistic regression. Study results showed that strain injuries were related to increased age, increased body mass index (BMI), and maintenance, custodial, and direct-caregiver employment types. Repetitive motion injuries were related to increased BMI and clerical and custodial employment types. Exposure/reaction injuries were related to increased age, increased BMI, and maintenance, custodial, and direct-caregiver employment types. Contact/assault injuries were related to increased age, increased BMI, and maintenance, custodial, and direct-caregiver employment types. All injury types were most often related to female gender and full-time employment status. Reformulating policies to improve screening, prevention, and education for those at risk for certain injury types may limit WRI occurrences and costs.

Associations of occupational standing with musculoskeletal symptoms: a systematic review with meta-analysis

OBJECTIVE

Given the high exposure to occupational standing in specific occupations, and recent initiatives to encourage intermittent standing among white-collar workers, a better understanding of the potential health consequences of occupational standing is required. We aimed to review and quantify the epidemiological evidence on associations of occupational standing with musculoskeletal symptoms.

DESIGN

A systematic review was performed. Data from included articles were extracted and described, and meta-analyses conducted when data were sufficiently homogeneous.

DATA SOURCES

Electronic databases were systematically searched.

ELIGIBILITY CRITERIA

Peer-reviewed articles on occupational standing and musculoskeletal symptoms from epidemiological studies were identified.

RESULTS

Of the 11 750 articles screened, 50 articles reporting 49 studies were included (45 cross-sectional and 5 longitudinal; n=88 158 participants) describing the associations of occupational standing with musculoskeletal symptoms, including low-back (39 articles), lower extremity (14 articles) and upper extremity (18 articles) symptoms. In the meta-analysis, 'substantial' (>4 hours/workday) occupational standing was associated with the occurrence of low-back symptoms (pooled OR (95% CI) 1.31 (1.10 to 1.56)). Evidence on lower and upper extremity symptoms was too heterogeneous for meta-analyses. The majority of included studies reported statistically significant detrimental associations of occupational standing with lower extremity, but not with upper extremity symptoms.

CONCLUSIONS

The evidence suggests that substantial occupational standing is associated with the occurrence of low-back and (inconclusively) lower extremity symptoms, but there may not be such an association with upper extremity symptoms. However, these conclusions are tentative as only limited evidence was found from high-quality, longitudinal studies with fully adjusted models using objective measures of standing.

Muscular Activation Pattern of Bilateral Extensors Response to Asymmetric Hand Lifting During Trunk Flexion-extension Performance

The authors' purpose was to test the effect of asymmetric hand lifting on muscular activation patterns of 3 bilateral extensors. Eighteen male university students without back pain were volunteered. Each performed flexion-extension randomly with conditions of right lifting, left lifting, and nonlifting. Surface electromyography from bilateral thoracic, lumbar erector spinae, and hamstring was recorded. The cross-correlation and relative intensity in paired muscles of bilateral extensors was calculated in flexion as well as extension period. The results showed that the cross-correlation coefficient was decreased and the phase lag as well as the relative intensity of bilateral extensors was increased significantly in thoracic level. The phase lag as well as the relative intensity of bilateral extensors was increased significantly in lumbar level. It was concluded that asymmetric lifting has a significant effect on muscular activation of bilateral extensors in thorax level, which causes the ipsilateral extensor to activate larger and longer. Asymmetric lifting also has some effect on muscular activation of bilateral extensors in lumbar level but with less extent than in thorax level, which causes contralateral extensor to activate larger and longer. Asymmetric lifting seems to have no significant effect on muscular activation of bilateral hamstring.

Review Article: Is sitting-while-at-work associated with low back pain? A systematic, critical literature review

Objectives: To present a critical review and evaluate recent reports investigating sitting-while-at-work as a risk factor for low back pain (LBP). Methods: The Medline, Embase and OSH-ROM databases were searched for articles dealing with sitting at work in relation to low back pain for the years 1985-97. The studies were divided into those dealing with sitting-while-working and those dealing with sedentary occupations. Each article was systematically abstracted for core items. The quality of each article was determined based on the representativeness of the study sample, the definition of LBP, and the statistical analysis. Results: Thirty-five reports were identified, 14 dealing with sitting-while-working and 21 with sedentary occupations. Eight studies were found to have a representative sample, a clear definition of LBP and a clear statistical analysis. Regardless of quality, all but one of the studies failed to find a positive association between sitting-while-working and LBP. High quality studies found a marginally negative association for sitting compared to diverse workplace exposures, e.g. standing, driving, lifting bending, and compared to diverse occupations. One low quality study associated sitting in a poor posture with LBP. Conclusions: The extensive recent epidemiological literature does not support the popular opinion that sitting-while-at-work is associated with LBP.

Review Article: Is sitting-while-at-work associated with low back pain? A systematic, critical literature review

Objectives: To present a critical review and evaluate recent reports investigating sitting-while-at-work as a risk factor for low back pain (LBP). Methods: The Medline, Embase and OSH-ROM databases were searched for articles dealing with sitting at work in relation to low back pain for the years 1985-97. The studies were divided into those dealing with sitting-while-working and those dealing with sedentary occupations. Each article was systematically abstracted for core items. The quality of each article was determined based on the representativeness of the study sample, the definition of LBP, and the statistical analysis. Results: Thirty-five reports were identified, 14 dealing with sitting-while-working and 21 with sedentary occupations. Eight studies were found to have a representative sample, a clear definition of LBP and a clear statistical analysis. Regardless of quality, all but one of the studies failed to find a positive association between sitting-while-working and LBP. High quality studies found a marginally negative association for sitting compared to diverse workplace exposures, e.g. standing, driving, lifting bending, and compared to diverse occupations. One low quality study associated sitting in a poor posture with LBP. Conclusions: The extensive recent epidemiological literature does not support the popular opinion that sitting-while-at-work is associated with LBP.

Low Back Pain in an Urban Population in Southwest Nigeria

This cross-sectional study was designed to determine the prevalence and risk factors for low back pain in an urban community. A house-to-house enquiry was conducted using a questionnaire administered by trained interviewers. Four hundred and seventy-four respondents, 271 men (57%) and 203 women (43%) participated in the study. The 12-month prevalence of low back pain was 44%, while the point prevalence was 39%. Back pain was more prevalent among men (49%) than women (39%). It was also associated with a history of trauma and low educational status. The prevalence of back pain was highest among farmers (85%) and lowest among housewives (32%). The prevalence of low back pain in this community is comparable to levels recorded in industrialized countries. However, in this study low back pain did not feature as a main cause of morbidity, accounting for a mean of 3 days off work per person per year.

Association Between Farm Machinery Operation and Low Back Disorder in Farmers: A Retrospective Cohort Study

OBJECTIVE

The association between whole body vibration (WBV) as measured by annual accumulated use of all-terrain vehicles (ATV)/combine/tractor operation and low back disorders (LBDs) among farmers was investigated.

METHODS

Saskatchewan Farm Injury Cohort Study data was used. Baseline data were collected in 2007 on the three vehicle types and other factors. Follow-up data on LBD symptoms were collected during 2013 resulting in 1149 samples.

RESULTS

Adjusted for age, education, and gender, LBDs were associated with tractor operation for 1 to 150 hours/year (Relative Risk [RR] = 1.23, 95%CI 1.05 to 1.44), 151 to 400 hours/year (RR = 1.32, 95%CI 114 to 1.54) and 401+ hours/year (RR = 1.34, 95%CI 1.15 to 1.56). Additionally, hip symptoms were associated with tractor operation. Only unadjusted associations were found in combine and ATV operation.

CONCLUSIONS

Duration of tractor operation and older age are important predictors of both low back and hip symptoms in farmers.

Relationship between spinal range of motion and trunk muscle activity during trunk rotation

[Purpose] The aim of this study was to clarify the relationship between spinal range of motion and trunk muscle activity during trunk rotation using a three-dimensional motion analysis system and surface electromyography. [Subjects and Methods] The subjects comprised 11 healthy men. A three-dimensional motion analysis system measured the trunk rotational angle of 4 segments of the thoracic vertebrae and 2 segments of the lumbar vertebrae. Surface electromyography measured the activities of the unilateral latissimus dorsi, lumbar multifidus, rectus abdominis, external oblique, internal oblique, and transversus abdominis muscles. [Results] During ipsilateral rotation at thoracic vertebral levels, the muscle activity of the latissimus dorsi and external oblique was significantly increased compared with the activity in the 0–10% range of trunk rotation. During early ipsilateral rotation at lumbar vertebral levels, the muscle activity of the internal oblique and transversus abdominis was significantly increased compared with that in the 0–10% range of trunk rotation. During contralateral rotation at both thoracic and lumbar vertebral levels, the muscle activity of the external oblique was significantly increased compared with that in the 0–10% range of trunk rotation. [Conclusion] This study indicates that it is important to consider vertebral segments and spinal range of motion during trunk rotation.

Monitor height ergonomics: A comparison of operating room video display terminals

A surgeon's eyes should be positioned 1 meter (m) distant and no more than 15° below the top of an operating monitor (0.27 m). We sought to determine which operating room video display terminal can best accommodate ergonomically optimized gaze during surgery. Floor to eye height was measured for surgeons in seated, perched, and standing positions. These ranges were then compared to vertical displacement ranges for monitors measured from floor to top of the screen. Eye height was measured for standing (1.56-1.80 m), perched (1.40-1.65 m), and seated (1.10-1.32 m) positions. The minimum distance (min) between the floor and the top of the monitor and the vertical mobility range (VR) of the monitor were measured throughout a tertiary medical center including towers with boom arms (TcB) (min: 1.58 m, VR: 0.37 m), towers without booms (TsB) (min: 1.82 m, VR: 0.025 m), ceiling mounted booms (CMB) (min: 1.34 m:, VR: 1.04 m), and portable monitors (PM) (min: 1.73 m, VR: 0.04 m). The tangent of 15° declination was used to calculate a correction factor to determine the minimum optimal ergonomic display height. The correction factor was subtracted from the eye height at each position to determine the lowest target height and the highest target floor to eye distance for each position. Analysis of variance with least significant difference post hoc testing identified all minimum distances and vertical ranges to be statistically different (p < 0.001). Monitor vertical displacement varied between styles of carts. CMB video display terminal systems can accommodate standing, perched and the tallest seated surgeons. TcB, TsB and PM systems cannot adequately accommodate all standing, perched or seated surgeons.

Prevalence and impacts of low back pain among peasant farmers in south-west Nigeria

OBJECTIVES

A relationship between low back pain (LBP) and poor postures has been previously established with a high prevalence observed in many occupations. This study aimed to investigate the prevalence of LBP, associated risk factors and impacts on farmers in South-West Nigeria.

MATERIALS AND METHODS

Six hundred and four farmers completed a 36-item closed-ended questionnaire which was translated to Yoruba language with content validity and back translation done after-wards. The questionnaire sought information on demographic data, 12-month prevalence, severity, history, causes and management of LBP, and its impacts on farm activities and the activities of daily living. Data was analyzed using the Statistical Package for Social Sciences (SPSS) version 17. Data was summarized using descriptive statistics of mean, range, frequency, standard deviation, percentage. Chi2 and Mann-Whitney-U test were used to find association between variables. The level of significance was set at α = 0.05.

RESULTS

The 12-month prevalence of LBP among the respondents was 74.4%. Low back pain was described as moderate in 53.4%. Prolonged bending (51.3%) was the most related risk factor. A consider-able proportion (65.9%) of the respondents were unable to continue some of the previously enjoyed activities. Males had significantly higher (p < 0.05) prevalence, recurrence and duration of LBP than the females.

CONCLUSION

There is a high prevalence of LBP among farmers in South-West Nigeria. Age, sex and years of involvement in farming have a significant influence on the prevalence of LBP.

Is objectively measured sitting time associated with low back pain? A cross-sectional investigation in the NOMAD study

Background

Studies on the association between sitting time and low back pain (LBP) have found contrasting results. This may be due to the lack of objectively measured sitting time or because socioeconomic confounders were not considered in the analysis.

Objectives

To investigate the association between objectively measured sitting time (daily total, and occupational and leisure-time periods) and LBP among blue-collar workers.

Methods

Two-hundred-and-one blue-collar workers wore two accelerometers (GT3X+ Actigraph) for up to four consecutive working days to obtain objective measures of sitting time, estimated via Acti4 software. Workers reported their LBP intensity the past month on a scale from 0 (no pain) to 9 (worst imaginable pain) and were categorized into either low (≤5) or high (>5) LBP intensity groups. In the multivariate-adjusted binary logistic regression analysis, total sitting time, and occupational and leisure-time sitting were both modeled as continuous (hours/day) and categorical variables (i.e. low, moderate and high sitting time).

Results

The multivariate logistic regression analysis showed a significant positive association between total sitting time (per hour) and high LBP intensity (odds ratio; OR=1.43, 95%CI=1.15-1.77, P=0.01). Similar results were obtained for leisure-time sitting (OR=1.45, 95%CI=1.10-1.91, P=0.01), and a similar but non-significant trend was obtained for occupational sitting time (OR=1.34, 95%CI 0.99-1.82, P=0.06). In the analysis on categorized sitting time, high sitting time was positively associated with high LBP for total (OR=3.31, 95%CI=1.18-9.28, P=0.03), leisure (OR=5.31, 95%CI=1.57-17.90, P=0.01), and occupational (OR=3.26, 95%CI=0.89-11.98, P=0.08) periods, referencing those with low sitting time.

Conclusion

Sitting time is positively associated with LBP intensity among blue-collar workers. Future studies using a prospective design with objective measures of sitting time are recommended.

Musculoskeletal disorders and occupational exposures: How should we judge the evidence concerning the causal association?

Musculoskeletal disorders (MSDs) affecting the back, upper and lower extremities are widespread in the general population, implying a variety of causal factors. Multiple causes are not mutually exclusive, and a high background rate does not preclude associations with specific factors that are uncommon in the general population. MSDs have well-documented associations with occupational ergonomic stressors such as repetitive motion, heavy lifting, non-neutral postures, and vibration. Organizational features of the work environment, such as time pressure and low decision latitude, may also play a role, at least by potentiating the effects of physical loading. Numerous systematic reviews have mostly concurred with these overall findings. Nevertheless, some continue to debate whether MSDs are sometimes work-related, even for those performing jobs with repetitive and routinized tasks, heavy lifting, and/or pronounced postural strain. This article discusses (1) some epidemiologic features of MSDs that underlie that debate; and (2) the question of what should appropriately be considered a gold standard for scientific evidence on an etiological question such as the health effects of a non-voluntary exposure, such as an occupational or environmental agent. In particular, randomized clinical trials have little relevance for determining the health effects of non-therapeutic risk factors.

Ergonomic implementation and work station design for quilt manufacturing unit

Background:

Awkward, extreme and repetitive postures have been associated with work related musculoskeletal disorders and injury to the lowerback of workers engaged in quilting manufacturing unit. Basically quilt are made manually by hand stitch and embroidery on the quilts which was done in squatting posture on the floor. Mending, stain removal, washing and packaging were some other associated work performed on wooden table. their work demands to maintain a continuous squatting posture which leads to various injuries related to low back and to calf muscles.

Material and Methods:

The present study was undertaken in Tarai Agroclimatic Zone of Udham Singh Nagar District of Uttarakhand State with the objective to study the physical and physiological parameters as well as the work station layout of the respondent engaged on quilt manufacturing unit. A total of 30 subjects were selected to study the drudgery involved in quilt making enterprise and to make the provision of technology option to reduce the drudgery as well as musculoskeletal disorders, thus enhancing the productivity and comfortability.

Results:

Findings of the investigation show that majority of workers (93.33 per cent) were female and very few (6.66 per cent) were the male with the mean age of 24.53±6.43. The body mass index and aerobic capacity (lit/min) values were found as 21.40±4.13 and 26.02±6.44 respectively. Forty per cent of the respondents were having the physical fitness index of high average whereas 33.33 per cent of the respondents had low average physical fitness. All the assessed activities involved to make the quilt included a number of the steps which were executed using two types of work station i.e squatting posture on floor and standing posture using wooden table. A comparative study of physiological parameters was also done in the existing conditions as well as in improved conditions by introducing low height chair and wooden spreader to hold the load of quilt while working, to improve the work posture of the worker. The average working heart rate values were found to reduced by performing the activity using improved technology followed by energy expenditure (6.99 kj/min), total cardiac cost of work (1037.95 beats), physiological cost of work (103.79 beats) and rate of perceived rate of exertion to the score of 2.6 Results of postural analysis that is change in motion at cervical region reveal that range of motion in case of extension was found beyond the normal range in existing setup where as it reduced to normal range in improved work station.

Conclusion:

The finding of the study concludes that to ensure safety and to reduce occupational health hazards while performing the activity, an ergonomically designed work station by introduction of improved technology option will be a right choice which also enhances the productivity.

[Review of dose-response relationship between low level vibration and lower back pain]

OBJECTIVES

Whole-body vibration (WBV) with high level acceleration is found in the workplaces of construction and mining, and has been reported to be associated with low back pain (LBP) experienced by operators of heavy vehicles as an occupational health problem. Because the work conditions with exposure to WBV include bending and twisting of the low back and other factors, the causal relationship between WBV and LBP has not yet been affirmed. A review suggesting the dose-response relationship between WBV with low acceleration and LBP has been published, although there is little evidence supporting the causal relationship. Therefore, we reviewed the dose-response relationship between WBV with low acceleration and LBP.

METHODS

We examined original articles which reported a dose-response relationship between WBV and LBP in addition to review articles with almost the same aims.

RESULTS AND DISCUSSION

Studies which examined imaging findings such as CT and MRI, objective indicators of LBP, do not confirm the causal relationship. Although many studies demonstrated a positive relationship between working periods and incidence of LBP, there were very few reports which recognized a dose-response relationship for the vibration acceleration below 1.0 m/s(2) in which the 8-h energy-equivalent, combined frequency-weighted vibration of three diagonal, that is x, y and z, axes (root-sum-of-squares), Asum(8) was used as an index of vibration exposure.

CONCLUSION

This paper reject the hypothesis of a dose-response relationship between WBV with low acceleration and LBP, concluding there is no evidence linking low level exposure to WBV with LBP for the Japan Society for Occupational Health to recommend 0.35 m/s(2)/as of Asum(8) as a tentative occupational exposure limits for WBV.

Body mass index as a risk factor for developing chronic low back pain: a follow-up in the Nord-Trøndelag Health Study

STUDY DESIGN

A population-based, prospective cohort study.

OBJECTIVE

To determine whether overweight, obesity, or more generally an elevated body mass index (BMI) increase the probability of experiencing chronic low back pain (LBP) after an 11-year period, both among participants with and without LBP at baseline.

SUMMARY OF BACKGROUND DATA

Chronic LBP is a common disabling disorder in modern society. Cross-sectional studies suggest an association between an elevated BMI and LBP, but it is not clear whether this is a causal relationship.

METHODS

Data were obtained from the community-based HUNT 2 (1995-1997) and HUNT 3 (2006-2008) studies of an entire Norwegian county. Participants were 8733 men and 10,149 women, aged 30 to 69 years, who did not have chronic LBP at baseline, and 2669 men and 3899 women with LBP at baseline. After 11 years, both groups indicated whether they currently had chronic LBP, defined as pain persisting for at least 3 months continuously during the last year.

RESULTS

A significant positive association was found between BMI and risk of LBP among persons without LBP at baseline. The odds ratio for BMI 30 or more versus BMI less than 25 was 1.34 (95% confidence interval [CI], 1.08-1.67) for men and 1.22 (95% CI, 1.03-1.46) for women, in analyses adjusted for age, education, work status, physical activity at work and in leisure time, smoking, blood pressure, and serum lipid levels. A significant positive association was also established between BMI and recurrence of LBP among women. LBP status at baseline had negligible influence on subsequent change in BMI.

CONCLUSION

High values of BMI may predispose to chronic LBP 11 years later, both in individuals with and without LBP. The association between BMI and LBP is not explained by an effect of LBP on later change in BMI.

Anthropometry-corrected exposure modeling as a method to improve trunk posture assessment with a single inclinometer

Measuring trunk posture in the workplace commonly involves subjective observation or self-report methods or the use of costly and time-consuming motion analysis systems (current gold standard). This work compared trunk inclination measurements using a simple data-logging inclinometer with trunk flexion measurements using a motion analysis system, and evaluated adding measures of subject anthropometry to exposure prediction models to improve the agreement between the two methods. Simulated lifting tasks (n=36) were performed by eight participants, and trunk postures were simultaneously measured with each method. There were significant differences between the two methods, with the inclinometer initially explaining 47% of the variance in the motion analysis measurements. However, adding one key anthropometric parameter (lower arm length) to the inclinometer-based trunk flexion prediction model reduced the differences between the two systems and accounted for 79% of the motion analysis method's variance. Although caution must be applied when generalizing lower-arm length as a correction factor, the overall strategy of anthropometric modeling is a novel contribution. In this lifting-based study, by accounting for subject anthropometry, a single, simple data-logging inclinometer shows promise for trunk posture measurement and may have utility in larger-scale field studies where similar types of tasks are performed.

Whole-body vibration: is there a causal relationship to specific imaging findings of the spine?

STUDY DESIGN

Systematic review.

OBJECTIVE

To perform a systematic review of the available literature for those studies that evaluated the role of whole-body vibration (WBV) on the spine, using imaging modalities as well as an estimation of WBV exposure.

SUMMARY OF BACKGROUND DATA

Numerous comparative studies have reported a possible association between the occurrence of spinal symptoms and exposure to WBV. These exposures have commonly been examined in the work environment largely through self-reported questionnaires only. From a scientific perspective, the majority of studies emphasize symptoms and lack objective medical evidence, such as spinal imaging, to help establish a specific spinal disorder. Because both neck and low back pain comprise symptoms that can arise from a host of factors including age, a casual link between spinal disorders and WBV cannot be affirmed.

METHODS

MEDLINE and EMBASE were searched for studies related to WBV and spinal symptoms, diagnosis, and/or disorders. Our searches were limited to studies published prior to August 2011. The resulting 700 citations (after excluding 354 duplicates) were then screened by 3 independent reviewers on the basis of the following predetermined inclusion and exclusion criteria: inclusion-clinical studies with imaging evaluation (radiographs, computed tomographic scans, and/or magnetic resonance images) and documented WBV exposure (occupation, amount of WBV, and/or duration); exclusion-reliance solely on self-reporting of symptoms (neck pain, low back pain, and/or sciatica), those articles based on a clinical diagnosis without use of imaging, and in vitro/animal/biomechanical studies.

RESULTS

Only 7 studies met the inclusion criteria for this systematic review. Included were 5 retrospective cohort and 2 cross-sectional studies. Although mixed results and conclusions were found, the majority of studies did not identify an association between WBV exposure and an abnormal spinal imaging finding indicating damage of the spine. We should also stress that each included study has limitations secondary to quantifying WBV exposure accurately, both as a single encounter and as a total exposure over years.

CONCLUSION

Based on our results from this systematic review, no causality can be shown between WBV and abnormal spinal imaging findings. With the conflicting data available in the literature, WBV has not been established as a cause for objective spinal pathological changes on a scientific basis.

[Relatedness of occupational exposure to whole-body vibration and health, principally back symptoms]

OBJECTIVES

DISCUSSION is continuing about whether or not to update the Occupational Exposure Limit for Whole Body Vibration exposure (OELWBV) which was established in 1975 as a part of the Recommendation of Occupational Exposure Limits (OEL), issued by the Japan Society for Occupational Health. The objectives of this study were to clarify the necessity of the update and the adverse health effects of whole-body vibration by reviewing the literature and to help to compile a for detailed revisions.

SUBJECTS AND METHODS

Mainly referring to our preceding review, the current OELWBV exposure was examined. The relatedness of adverse health effects, principally back symptoms and occupational exposure to whole-body vibration (WBV) was examined by reviewing review papers, the original English papers referred to in those papers, and original English and Japanese references from 2002 to 2010 retrieved through a MEDLINE search.

RESULTS

The results show the necessity of updating the present OELWBV as soon as possible. The overwhelming majority of the literature consists of epidemiological studies showing the relatedness of WBV to back symptoms. Thirty epidemiological studies out of 28 literatures clearly show the presence of a relationship between WBV and back symptoms. Various indices of exposure to WBV and back symptoms show the dose response relationships. Among these, a few studies used A(sum)(8) (equivalent 8-hour r.m.s. acceleration value for the combined frequency-weighted vibration of three diagonal, that is x, y and z, axes) as the exposure index. All of these studies reported some dose-response relationship between WBV exposure and back symptoms.

DISCUSSION

Despite the clear presence or absence of a relationship between WBV and back symptoms, 0.5 m/s(2) seems to be the unconfirmed threshold of risk. Focusing on data of A(sum)(8), we suggest that the risk increases over the magnitude of 0.30 m/s(2). To clarify this, further epidemiological studies and others should focus on A(sum)(8) around 0.30 m/s(2).

CONCLUSIONS

The present OEL of WBV should be examined from the viewpoint of the risks of back symptoms referring to the epidemiological studies that show the larger risks of back symptoms in comparison with unexposed referent workers. We conclud that when updating the present OELWBV, A(sum)(8) should be taken into account for back symptoms, referring to the findings of epidemiological studies.

Individual participant data meta-analysis of mechanical workplace risk factors and low back pain

OBJECTIVES

We used individual participant data from multiple studies to conduct a comprehensive meta-analysis of mechanical exposures in the workplace and low back pain.

METHODS

We conducted a systematic literature search and contacted an author of each study to request their individual participant data. Because outcome definitions and exposure measures were not uniform across studies, we conducted 2 substudies: (1) to identify sets of outcome definitions that could be combined in a meta-analysis and (2) to develop methods to translate mechanical exposure onto a common metric. We used generalized estimating equation regression to analyze the data.

RESULTS

The odds ratios (ORs) for posture exposures ranged from 1.1 to 2.0. Force exposure ORs ranged from 1.4 to 2.1. The magnitudes of the ORs differed according to the definition of low back pain, and heterogeneity was associated with both study-level and individual-level characteristics.

CONCLUSIONS

We found small to moderate ORs for the association of mechanical exposures and low back pain, although the relationships were complex. The presence of individual-level OR modifiers in such an area can be best understood by conducting a meta-analysis of individual participant data.

The impact of self-reported exposure to whole-body-vibrations on the risk of disability pension among men: a 15 year prospective study

BACKGROUND

Whole-body-vibrations are often associated with adverse health effect but the long term effects are less known. This study investigates the association between occupational exposures to whole-body vibrations, and subsequent transition to disability pension.

METHODS

A total of 4215 male employees were followed up for subsequent disability pension retirement. Exposure to whole-body-vibration was self-reported while new cases of disability pension were retrieved from a national register.

RESULTS

The hazard ratio (HR) for disability pension retirement among men exposed to whole-body-vibrations was 1.61 (95% confidence interval (CI) 1.07-2.40) after adjustment for age, smoking habits, BMI, physical job demands and awkward work postures. In our model, with the available explanatory variables, 5.6% of the male disability pension cases were attributable to whole-body-vibrations.

CONCLUSIONS

Exposure to whole-body-vibrations predicts subsequent disability pension retirement. Continued reduction of whole-body-vibrations may reduce the number of new cases of disability pension.

Causal assessment of occupational lifting and low back pain: results of a systematic review

BACKGROUND CONTEXT

Low back pain (LBP) is a disorder that commonly affects the working population, resulting in disability, health-care utilization, and a heavy socioeconomic burden. Although the etiology of LBP remains uncertain, occupational activities have been implicated. Evaluating these potentially causal relationships requires a methodologically rigorous approach. Occupational repetitive and/or heavy lifting is widely thought to be a risk factor for the development of LBP.

PURPOSE

To conduct a systematic review of the scientific literature to evaluate the causal relationship between occupational lifting and LBP.

STUDY DESIGN

Systematic review of the literature.

SAMPLE

Studies reporting an association between occupational lifting and LBP.

OUTCOME MEASURES

Numerical association between different levels of exposure to occupational lifting and the presence or severity of LBP.

METHODS

A search was conducted using Medline, EMBASE, CINAHL, Cochrane Library, OSH-ROM, gray literature (eg, reports not published in scientific journals), hand-searching occupational health journals, reference lists of included studies, and content experts. Evaluation of study quality was performed using a modified version of the Newcastle-Ottawa Scale. Levels of evidence were evaluated for specific Bradford-Hill criteria (association, dose-response, temporality, experiment, and biological plausibility).

RESULTS

This search yielded 2,766 citations, of which 35 studies met eligibility criteria and 9 were considered high methodological quality studies, including four case-controls and five prospective cohorts. Among the high-quality studies, there was conflicting evidence for association with four studies reporting significant associations and five studies reporting nonsignificant results. Two of the three studies that assessed dose-response demonstrated a nonsignificant trend. There were no significant risk estimates that demonstrated temporality. No studies were identified that satisfied the experiment criterion. Subgroup analyses identified certain types of lifting and LBP that had statistically significant results, but there were none that satisfied more than two of the Bradford-Hill criteria.

CONCLUSIONS

This review uncovered several high-quality studies examining a relationship between occupational lifting and LBP, but these studies did not consistently support any of the Bradford-Hill criteria for causality. There was moderate evidence of an association for specific types of lifting and LBP. Based on these results, it is unlikely that occupational lifting is independently causative of LBP in the populations of workers studied. Further research in specific subcategories of lifting would further clarify the presence or absence of a causal relationship.

The effectiveness of walking as an intervention for low back pain: a systematic review

As current low back pain (LBP) guidelines do not specifically advocate walking as an intervention, this review has explored for the effectiveness of walking in managing acute and chronic LBP. CINAHL, Medline, AMED, EMBASE, PubMed, Cochrane and Scopus databases, as well as a hand search of reference lists of retrieved articles, were searched. The search was restricted to studies in the English language. Studies were included when walking was identified as an intervention. Four studies met inclusion criteria, and were assessed with a quality checklist. Three lower ranked studies reported a reduction in LBP from a walking intervention, while the highest ranked study observed no effect. Heterogeneity of study design made it difficult to draw comparisons between studies. There is only low-moderate evidence for walking as an effective intervention strategy for LBP. Further investigation is required to investigate the strength of effect for walking as a primary intervention in the management of acute and chronic LBP.

Causal assessment of occupational sitting and low back pain: results of a systematic review

BACKGROUND CONTEXT

Low back pain (LBP) is a common and disabling musculoskeletal disorder that often occurs in a working-age population. Determining the precise causation of LBP remains difficult. Any attempt to implicate a specific occupational activity in the genesis of LBP requires a methodologically rigorous approach.

PURPOSE

To conduct a systematic review of the scientific literature focused on evaluating the causal relationship between occupational sitting and LBP.

STUDY DESIGN

Systematic review of the literature using Medline, EMBASE, CINAHL, Cochrane Library, Occupational Safety and Health database, grey literature, hand-searching occupational health journals, reference lists of included studies, and content experts. Evaluation of study quality using a modified version of the Newcastle-Ottawa Scale. Summary levels of evidence supporting Bradford-Hill criteria for different categories of sitting and types of LBP.

SAMPLES

Studies reporting an association between occupational sitting and LBP.

OUTCOME MEASURES

Numerical association between different levels of exposure to occupational sitting and the presence or severity of LBP.

METHODS

A systematic review was performed to identify, evaluate, and summarize the literature related to establishing a causal relationship, according to Bradford-Hill criteria, between occupational sitting and LBP.

RESULTS

This search yielded 2,766 citations. Twenty-four studies met the inclusion/exclusion criteria and five were high-quality studies, including two case-controls and three prospective cohorts. Strong, consistent evidence was found for no association between occupational sitting and LBP. A moderate level of evidence was found for the absence of any dose-response trend. Risk estimates evaluating temporality were not statistically significant. Biological plausibility was not discussed in these studies. No evidence was available to assess the experiment criterion.

CONCLUSIONS

This review failed to uncover high-quality studies to support any of the Bradford-Hill criteria to establish causality between occupational sitting and LBP. Strong and consistent evidence did not support criteria for association, temporality, and dose response. Based on these results, it is unlikely that occupational sitting is independently causative of LBP in the populations of workers studied.