Association of Exposures to Seated Postures With Immediate Increases in Back Pain: A Systematic Review of Studies With Objectively Measured Sitting Time

Traditional versus dynamic sitting: Lumbar spine kinematics and pain during computer work and activity guided tasks

Dynamic sitting may mitigate low back pain during prolonged seated work. The current study compared pelvis and lumbar spine kinematics, pain, and work productivity, in traditional and dynamic sitting. Sixteen participants completed three 20-min blocks of computer work and activity guided tasks in a traditional office chair or backless and multiaxial rotating seat pan while kinematics were measured from accelerometers on the low back. Pain ratings were recorded on a visual analogue scale every 10 min. Similar pelvis and lumbar kinematics emerged when performing computer work in traditional and dynamic sitting. Pelvis and lumbar sagittal and frontal plane shifts and fidgets were largest for dynamic sitting in the activity guided tasks. Buttocks pain was higher in dynamic sitting, but low back pain and work productivity were unaffected. Dynamic sitting increased spine movement during activity guided tasks, without negatively impacting lumbar kinematics, low back pain, or productivity during seated computer work.

A modern way to teach and practice manual therapy

BACKGROUND

Musculoskeletal conditions are the leading contributor to global disability and health burden. Manual therapy (MT) interventions are commonly recommended in clinical guidelines and used in the management of musculoskeletal conditions. Traditional systems of manual therapy (TMT), including physiotherapy, osteopathy, chiropractic, and soft tissue therapy have been built on principles such as clinician-centred assessment, patho-anatomical reasoning, and technique specificity. These historical principles are not supported by current evidence. However, data from clinical trials support the clinical and cost effectiveness of manual therapy as an intervention for musculoskeletal conditions, when used as part of a package of care.

PURPOSE

The purpose of this paper is to propose a modern evidence-guided framework for the teaching and practice of MT which avoids reference to and reliance on the outdated principles of TMT. This framework is based on three fundamental humanistic dimensions common in all aspects of healthcare: safety, comfort, and efficiency. These practical elements are contextualised by positive communication, a collaborative context, and person-centred care. The framework facilitates best-practice, reasoning, and communication and is exemplified here with two case studies.

METHODS

A literature review stimulated by a new method of teaching manual therapy, reflecting contemporary evidence, being trialled at a United Kingdom education institute. A group of experienced, internationally-based academics, clinicians, and researchers from across the spectrum of manual therapy was convened. Perspectives were elicited through reviews of contemporary literature and discussions in an iterative process. Public presentations were made to multidisciplinary groups and feedback was incorporated. Consensus was achieved through repeated discussion of relevant elements.

CONCLUSIONS

Manual therapy interventions should include both passive and active, person-empowering interventions such as exercise, education, and lifestyle adaptations. These should be delivered in a contextualised healing environment with a well-developed person-practitioner therapeutic alliance. Teaching manual therapy should follow this model.

Lateral Pelvis and Lumbar Motion in Seated and Standing Office Work and Their Association With Transient Low Back Pain

OBJECTIVE

To assess frontal plane motion of the pelvis and lumbar spine during 2 h of seated and standing office work and evaluate associations with transient low back pain.

BACKGROUND

Although bending and twisting motions are cited as risk factors for low back injuries in occupational tasks, few studies have assessed frontal plane motion during sedentary exposures.

METHODS

Twenty-one participants completed 2 h of seated and standing office work while pelvic obliquity, lumbar lateral bending angles, and ratings of perceived low back pain were recorded. Mean absolute angles were compared across 15-min blocks, amplitude probability distribution functions were calculated, and associations between lateral postures and low back pain were evaluated.

RESULTS

Mean pelvic obliquity (sit = 4.0 ± 2.8°, stand = 3.5 ± 1.7°) and lumbar lateral bending (sit = 4.5 ± 2.5°, stand = 4.1 ± 1.6°) were consistently asymmetrical. Pelvic obliquity range of motion was 4.7° larger in standing (13.6 ± 7.5°) than sitting (8.9 ± 8.7°). In sitting, 52% (pelvis) and 71% (lumbar) of participants, and in standing, 71% (pelvis and lumbar) of participants, were considered asymmetric for >90% of the protocol. Lateral postures displayed weak to low correlations with peak low back pain (R ≤ 0.388).

CONCLUSION

The majority of participants displayed lateral asymmetries for the pelvis and lumbar spine within 5° of their upright standing posture.

APPLICATION

In short-term sedentary exposures, associations between lateral postures and pain indicated that as the range in lateral postures increases there may be an increased possibility of pain.

Association of meeting 24-hour movement guidelines with low back pain among adults

Background

According to recently published 24-hour movement guidelines, adults should spend: ≥150 minutes/week in moderate-to-vigorous physical activity (MVPA); <8 hours/day in sedentary behaviour (SB); and 7-9 hours/day sleeping.

Objective

We explored the association between meeting these recommendations and low back pain (LBP)-the most common musculoskeletal disorder.

Methods

We collected self-reported data from 2333 adults about: MVPA, SB and sleep duration; frequency and intensity of LBP; and sociodemographic and lifestyle characteristics.

Results

Meeting a combination of SB and sleep recommendations was associated with lower odds of LBP in the past week and past month (adjusted odds ratio [OR]: 0.64 and 0.52, respectively; p < 0.05 for both). Among LBP sufferers, meeting any combination of recommendations that includes sleep was associated with lower odds of frequent (OR range: 0.49-0.61; p < 0.05 for all) and intense (OR range: 0.39-0.66; p < 0.05 for all) LBP in the past week, while meeting a combination of SB and sleep recommendations or all three recommendations was associated with lower odds of intense LBP in the past month and past year (OR range: 0.50-0.68; p < 0.05 for all). The likelihood of experiencing higher frequency and intensity of LBP decreased with the number of recommendations met (p for linear trend < 0.05).

Conclusion

Meeting the SB and sleep recommendations in combination is associated with a lower likelihood of LBP, while adhering to the overall 24-hour movement guidelines or any combination of recommendations that includes sleep is associated with lower frequency and intensity of LBP among LBP sufferers.

Effect of office chair design features on lumbar spine posture, muscle activity and perceived pain during prolonged sitting

Chair design features are typically compared using multiple seats, which can lead to confounding effects. Using a single chair, configurable to four designs (control, lumbar support, seat pan tilt and scapular relief), we investigated the effect of chair design on spine posture and movement, muscle activity and perceived pain in a sample of 31 asymptomatic adults. A total of 39% of the population were classified as pain developers, having significantly higher peak pain levels across most body regions. The lumbar support and seat pan tilt condition resulted in more neutral spine and pelvic postures. Greater muscle activity was found in the seat pan condition and non-pain developers displayed lower spine muscle activation levels overall. Despite some improvements in spine posture, sitting-induced pain was present in the study sample at similar proportions to those reported previously. Future studies may consider investigating interventions targeted to sitting-induced pain developers as opposed to the general population. Practitioner summary: Four office chair configurations were tested. The lumbar support and seat pan tilt conditions resulted in the most neutral back posture but did not mitigate the clinically significant levels of sitting-induced pain experienced by a large portion of the tested sample. Future work should target interventions to these individuals.

The Use of Sensors to Prevent, Predict Transition to Chronic and Personalize Treatment of Low Back Pain: A Systematic Review

Non-specific low back pain (NSLBP) is a highly prevalent condition that implies substantial expenses and affects quality of life in terms of occupational and recreational activities, physical and psychological health, and general well-being. The diagnosis and treatment are challenging processes due to the unknown underlying causes of the condition. Recently, sensors have been included in clinical practice to implement its management. In this review, we furthered knowledge about the potential benefits of sensors such as force platforms, video systems, electromyography, or inertial measure systems in the assessment process of NSLBP. We concluded that sensors could identify specific characteristics of this population like impaired range of movement, decreased stability, or disturbed back muscular activation. Sensors could provide sufferers with earlier diagnosis, prevention strategies to avoid chronic transition, and more efficient treatment approaches. Nevertheless, the review has limitations that need to be considered in the interpretation of results.

Work-related musculoskeletal disorders and risk factors among weavers: A cross-sectional study

Background

Work-related musculoskeletal disorders (WRMSDs) are a major health issue for low-income countries because of their high prevalence among workers and on account of the scarcity of ergonomic preventative measures in the workplace.

Objectives

To determine the prevalence of WRMSDs among weavers, assess their consequences, and analyse the associated occupational risk factors.

Method

A cross-sectional survey was carried out among 257 handloom weavers using the Nordic questionnaireand the working conditions were assessed through a descriptive analysis using the key indicator method.

Results

The WRMSDs annual prevalence was 85% in all parts of the body, 71% for the low back region, 41% for the shoulders, and 37% for the knees. One quarter of the weavers indicated having stopped work for 1-30 days because of their low back pain (LBP). The prevalence of WRMSDs was associated with the number of hours worked per day, the years of experience, and age. Long working hours, load carrying (> 20 kg - 25 kg), awkward postures, repetitive limb movements, and unfavourable environmental conditions were identified as occupational risk factors.

Conclusion

Work-related musculoskeletal disorders are common among weavers and LBP is the most frequently cited disorder and the primary reason for work interruptions and a decrease of activities. The prevalence of WRMSDs is associated with professional and personal factors. Actions based on ergonomic rules are necessary to prevent WRMSDs.

Clinical implications

Our study highlights the issue of WRMSDs and the need for prevention in the informal sector, which constitutes the major part of economic activity in low-income countries.

Prolonged slumped sitting causes neck pain and increased axioscapular muscle activity during a computer task in healthy participants - A randomized crossover study

INTRODUCTION

Sitting posture may contribute to spinal pain. Effects of postures on pain, sensitivity and muscle activity during computer tasks were investigated.

METHODS

Twenty-five healthy participants, seated at a workstation without backrest, completed four, 15-min typing tasks: A)Upright with forearm-support; B)Upright without forearm-support; C)Slumped with forearm-support; D)Slumped without forearm-support. Participants rated pain every minute on a numerical rating scale (NRS). RMS-EMG was recorded from upper/lower trapezius (UT, LT), serratus anterior and anterior/middle deltoid. At baseline and after tasks, pressure pain thresholds (PPTs) were recorded bilaterally over the head, UT, and leg.

RESULTS

All tasks caused clinically relevant increased NRS (≥2/10) compared to baseline (P < 0.001). NRS was higher in Task-D (P < 0.003) and lower in Task-B (P < 0.005) than others. PPTs did not change from baseline. Task-D caused higher UT and LT RMS-EMG (P < 0.02) than other tasks.

CONCLUSION

A 15-min task caused pain irrespective of posture with some causing larger changes than others.

Effects of Using a Shoulder/Scapular Brace on the Posture and Muscle Activity of Healthy University Students during Prolonged Typing-A Randomized Controlled Cross-Over Trial

Laptop use appears to contribute to poor working postures and neck pain among university students. Postural braces have the potential to improve upper back/neck posture and therefore might have a role as an ergonomic aid for this population. Therefore, the purpose of this study was to assess the short-term effects of scapular bracing on pain, fatigue, cervicothoracic posture, and the activity of the neck and upper-back muscles in healthy college students. A randomized controlled crossover trial was conducted to evaluate the self-reported pain and fatigue, the amplitude and median frequency of surface electromyography in neck extensors, upper trapezius, and lower trapezius, as well as the neck and shoulder sagittal alignment (measured by inertial sensors and digital photographs) during a 30-min typing task in a sample of young, healthy university students with or without a scapular brace. The brace condition resulted in significantly smaller levels of bilateral trapezius muscle activity (p < 0.01). Rounded shoulder posture was slightly better in the brace condition, but these differences were not significant (p > 0.05). There were no significant immediate differences in pain or fatigue scores, neck alignment, or the electromyographic activity of the other muscles tested between brace and non-brace conditions (all p > 0.05). However, bracing appears to immediately reduce the electromyographic activity of the lower trapezius muscles (p < 0.05). These findings shed some light on the possible advantages of scapular bracing for enhancing laptop ergonomics in this group of individuals. Future studies are warranted to evaluate the effects of different types of braces, the importance of matching the brace to the user, and the short- and long-term effects of brace use on computer posture and muscle activity.

Does a break from sitting change biomechanical outcome measures or transient pain? A laboratory-based experimental study

BACKGROUND

Sitting can induce transient low back pain (LBP) in healthy individuals. A rest from sitting should provide relief, however, the parameters of breaks (activity type, intensity, duration, and timing) are not currently known.

OBJECTIVE

The purpose of this study was to examine the effect of 2-minute walking breaks at 40-minute intervals on sitting-induced LBP.

METHODS

Thirty-two healthy participants were recruited for a within-control study: two randomly presented sessions of sitting for 2 hours with and without breaks. Outcome measures were compared between condition and pain group using a three-way ANOVA with significance atp > 0.05.

RESULTS

Walking breaks at 40-minute intervals result in significantly lower pain ratings than those taken immediately before the break for sitting-induced back pain developers. However, this relief is short lived (<10 minutes), with ratings increasing to pre-break levels once the sitting exposure resumes. There were no differences in biomechanical factors between sessions. Regardless of session type, pain developers displayed higher spine fidget frequency than non-pain developers, females sat with less spine flexion, with greater gluteal activation levels, and with their center of pressure approximately half a centimeter to the left and forward compared to males, and males had significantly greater peak pressures over a smaller area compared to females.

CONCLUSION

Walking breaks at 40-minute intervals provide significant, but temporary, relief of sitting-induced back pain for pain developers. Future work should optimize break parameters and examine the longer-term benefit of breaks, especially for individuals that are not able to tolerate sitting for extended durations.

An investigation of the flexion relaxation ratio in adults with and without a history of self-reported low back pain and transient sitting-induced pain

It is unknown whether the presence of sitting-induced pain or a clinical history of low back pain (LBP) changes spine function outcomes such as the flexion relaxation ratio (FRR). The purpose of this investigation was to determine whether sitting-induced pain or a history of non-specific LBP results in a different FRR. Forty-seven participants were instrumented with surface electromyography over erector spinae at L1, and accelerometers at L1 and S2. Standing maximum lumbar flexion trials were taken preceding and following a 1-hour sitting trial. Pain ratings during sitting and history of LBP were used to group participants for analysis. FRR values taken after the sitting exposures were compared between those that did and did not develop pain during sitting. Baseline FRR values were compared participants with and without a history of LBP. No significant differences in FRR were found for either pain groups (p = 0.11) or clinical history (p = 0.85). Lack of differences may be due to participants not currently experiencing a clinical episode of pain when the ratio was measured and/or because 1-hour sitting exposure was not long enough to induce pain modulation. The findings suggest that neither sitting-induced pain development or clinical history need to be controlled to prevent confounding of FRR.

Association between chronic low back pain and regular exercise, sedentary behaviour and mental health before and during COVID-19 pandemic: insights from a large-scale cross-sectional study in Germany

Background

Nonspecific chronic low back pain (CLBP) is a complex symptom with numerous possible causes and influencing factors. Understanding how modifiable factors affect the course of CLBP is important for preventing progression. As the COVID-19 pandemic has changed the lifestyle of many people, this study paper assessed whether it also changed the influence of modifiable lifestyle factors (regular exercise and sedentary behaviour) and mental health factors (anxiety and depression) on CLBP pain intensity and disability by comparing the strength of these associations before and during the pandemic. We hypothesised that the importance of regular physical activity and good mental health for CLBP patients would increase during the pandemic.

Methods

These questions were investigated in a cross-sectional study of insurance claims data and self-reported data from various questionnaires from 3,478 participants in a German CLBP health intervention (2014–2021) by calculating pre- and intra-pandemic odds ratios (OR) and 95% confidence intervals (CI) for each variable of interest and outcome. Potential confounders were also considered. Pandemic status was treated as an effect modifier. Based on the date of enrolment, participants were classified as “pre-pandemic” or “pandemic”.

Results

Regularly exercising ≥ 4 h/week significantly reduced the odds of high disability for men (OR 0.49, 95% CI 0.31 – 0.79, p = 0.003) and women (OR 0.30, 95% CI 0.14 – 0.563, p = 0.002) and reduced the probability of severe pain in women (OR 0.37, 95% CI 0.21 – 0.65, p < 0.001). Each one-point increase in PHQ-4 score for anxiety and depression increased the OR of high pain intensity by 1.25 points (95% CI 1.18 – 1.34, p < 0.001). A clear impact of COVID-19 lockdowns was observed. In individuals who exercised ≥ 4 h/week the OR of high disability was 0.57 (95% CI 0.36 – 0.92, p = 0.021) in the pre-pandemic group compared to 0.29 (95% CI 0.12 – 0.56, p = 0.002) in the pandemic group. The probability of high disability increased from an OR of 1.42 (95% CI 1.33 – 1.52, p < 0.001) per marginal increase in the PHQ-4 scale before the pandemic, to an OR of 1.73 (95% CI 1.58 – 1.89, p < 0.001) during the pandemic.

Conclusions

The magnitude of association of the factors that influenced high pain intensity and disability increased during the pandemic. On the one hand, the protective effect of regular exercising was greater in participants surveyed during lockdown. On the other hand, a higher risk through anxiety or depression during the lockdown was identified. An additional study with objective measures of sedentary behaviour and physical activity is needed to validate these results. More in-depth investigation of lockdown-induced associations between reduced daily physical activity, increased levels of anxiety and depression, and their effects on CLPB could also be worthwhile.

Trial registration

This study used routinely collected data from a CLBP intervention that was previously evaluated and registered in the German Registry of Clinical Trials under DRKS00015463 (04/09/2018). The original ethics approval, informed consent and self-reported questionnaire have remained unchanged and are still valid.

Is it possible to discriminate workers with a higher prevalence of low back pain considering daily exposure time in a work-related lumbar posture? A diagnostic accuracy study

The study aimed to develop and validate a cut-off for daily postures to discriminate workers with low back pain. The self-reported episode of low back pain in the last year and during the previous week and the total spent time in occupational postures of 529 workers were used to screen workers who more likely would report low back pain. The receiver operating characteristics curve verified the ability of daily time in each posture in discriminating workers with low back pain in a training sample. Then, the chi-squared test and measurements of the diagnostic accuracy were performed in the testing sample. The daily time spent in a given posture was not able to accurately discriminate against workers with low back pain. Total time spent walking was the only daily posture that discriminated workers with low back pain in the last year in the testing sample, albeit with low accuracy. Practitioner Summary: The daily time spent in a given posture was not able to accurately distinguish workers with low back pain. Total spent time in walking presented modest diagnostic accuracy and should be interpreted cautiously. The spent time in a particular posture did not detect workers with LBP in the last week.

Disability burden due to musculoskeletal conditions and low back pain in Australia: findings from GBD 2019

BACKGROUND

To report the national prevalence, years lived with disability (YLDs) and attributable risk factors for all musculoskeletal conditions and separately for low back pain (LBP), as well as compare the disability burden related to musculoskeletal with other health conditions in Australia in 2019.

METHODS

Global Burden of Disease (GBD) 2019 study meta-data on all musculoskeletal conditions and LBP specifically were accessed and aggregated. Counts and age-standardised rates, for both sexes and across all ages, for prevalence, YLDs and attributable risk factors are reported.

RESULTS

In 2019, musculoskeletal conditions were estimated to be the leading cause of YLDs in Australia (20.1%). There were 7,219,894.5 (95% UI: 6,847,113-7,616,567) prevalent cases of musculoskeletal conditions and 685,363 (95% UI: 487,722-921,471) YLDs due to musculoskeletal conditions. There were 2,676,192 (95% UI: 2,339,327-3,061,066) prevalent cases of LBP and 298,624 (95% UI: 209,364-402,395) YLDs due to LBP. LBP was attributed to 44% of YLDs due to musculoskeletal conditions. In 2019, 22.3% and 39.8% of YLDs due to musculoskeletal conditions and LBP, respectively, were attributed to modifiable GBD risk factors.

CONCLUSIONS

The ongoing high burden due to musculoskeletal conditions impacts Australians across the life course, and in particular females and older Australians. Strategies for integrative and organisational interventions in the Australian healthcare system should support high-value care and address key modifiable risk factors for disability such as smoking, occupational ergonomic factors and obesity.

Standing time and daily proportion of sedentary time are associated with pain-related disability in a one month accelerometer measurement in adults with overweight or obesity

OBJECTIVES

The association between the subjective experience of pain-related disability (PRD) and device-measured physical activity (PA) and sedentary behavior (SB) in overweight and obese adults is not well known. The aim of this study was to investigate the associations of pain markers with accelerometer-measured SB duration and different intensities of PA among physically inactive middle-aged adults with overweight or obesity.

METHODS

This cross-sectional analysis included 72 subjects (27 men) with mean age of 57.9 (SD 6.7) years and mean BMI of 31.6 (SD 4.1) kg/m2. SB and standing time (ST), breaks in sedentary time, light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA) were measured for four consecutive weeks (mean 25 days, SD 4) with a hip-worn triaxial accelerometer. Headache, musculoskeletal pain, back pain, and PRD were assessed by visual analog scales (VAS) and using the Oswestry disability index (ODI). RAND-36 questionnaire was applied to assess health-related quality of life. The associations were studied by linear models.

RESULTS

ST was positively and SB proportion was negatively associated with PRD when adjusted for age, sex, BMI, accelerometry duration, MVPA, pain medication use, and general health perceptions assessed by RAND-36. No associations were found between ST and back pain. SB or different PA intensities were not associated with pain experience at specific sites.

CONCLUSIONS

Longer daily ST, but not LPA or MVPA is associated with higher level of PRD. Correspondingly, higher proportion of SB is associated with lower level of PRD. This suggests that individuals with PRD prefer to stand, possibly to cope with pain. These results may highlight the importance of habitual standing behaviors in coping with experienced PRD in adults with overweight or obesity.

Monitoring calf circumference: changes during prolonged constrained sitting

Prolonged sitting has been associated with negative health effects; however, short-term time-varying exposure and response data is lacking. Twenty-two young and healthy participants were seated for 2 hours with the instruction to avoid the confounding effects of large leg movements while calf circumference, perceived discomfort, and lower limb muscle activity were collected. Calf circumference increased significantly (0.90 ± 0.32 cm) during sitting with no statistical differences between sexes. Perceived discomfort increased significantly over time in the low back and gluteal regions (p = 0.001-0.072, η_p²=0.080-0.360). On average, it took 20.31 ± 10.87 minutes of walking for calf measures to return to pre-sitting baseline. These results suggest that sitting for 2 hours without activity breaks may not be advisable and that recovery may take longer than expected. The exposure/response data from this study may be helpful in the design of future studies, with a larger and more general population, aiming to better define recommended duration/activity ratios for sitting-focused occupations. Practitioner summary: Leg swelling is a concern in prolonged sitting. In this study of young, healthy participants, we found a 2 hour constrained sitting exposure (controlling for large leg movements) induced significant increases in calf circumference that took an average of 20.31 ± 10.87 min of walking to return to baseline.Abbreviations: FMD: flow-mediated dilation, GSC: gastrocnemius; TA: tibialis anterior; EMG: electromyography; VAS: visual analog scale; MVC: maximum voluntary contractions.

Influence of car seat firmness on seat pressure profiles and perceived discomfort during prolonged simulated driving

During a driving task, the seat-driver interface is particularly influenced by the external environment and seat features. This study compares the effect of two different seats (S₁ - soft & S₂ - firm) and the effect of visual simulation of different road types (city, highway, mountain, country), on pressure distribution and perceived discomfort during prolonged driving. Twenty participants drove two 3-h sessions (one per seat) on a static simulator. Contact Pressure (CP), Contact Surface (CS), and Seat Pressure Distribution Percentage (SPD%) were analyzed throughout, using two pressure mats positioned on seat cushion and backrest. Whole-body and local discomfort for each body part were rated every 20 min. The softer seat, S₁, induced a greater contact surface on cushion and backrest and a lower SPD%, reflecting better pressure distribution. Pressure profiles were asymmetrical for both S₁ and S_2, with higher CP under left buttock (LBu) and right lower back (RLb) and greater CS under thighs and RLb. Pressure distribution was less homogeneous on mountain and city roads than on monotonous roads (highway and country). Despite the pressure differences between the seats, however, both led to similar increases in perceived whole-body discomfort throughout the driving session. Moreover, the highest discomfort scores were in the neck and the lower back areas, whatever the seat. These findings on pressure variables may have implications for the design of backrests and cushions to ensure more homogeneous pressure distribution, even though this is not shown to minimize perceived driver discomfort.

Thirty Minutes Identified as the Threshold for Development of Pain in Low Back and Feet Regions, and Predictors of Intensity of Pain during 1-h Laboratory-Based Standing in Office Workers

This study with 40 office workers investigated (a) the effect of time spent standing on low- back and lower limb pain during a 1-h laboratory-based task; (b) the standing time after which a significant increase in pain is likely; and (c) the individual, physical and psychosocial factors that predict pain. The primary outcome was bodily location of pain and pain intensity on a 100-mm Visual Analogue Scale recorded at baseline and every 15 min. Physical measures included trunk and hip motor control and endurance. Self-report history of pain, physical activity, psychosocial job characteristics, pain catastrophizing and general health status were collected. Univariate analysis and regression models were included. The prevalence of low-back pain increased from 15% to 40% after 30 min while feet pain increased to 25% from 0 at baseline. The intensity of low-back and lower limb pain also increased over time. A thirty-minute interval was identified as the threshold for the development and increase in low-back and feet pain. Modifiable factors were associated with low-back pain intensity-lower hip abductor muscle endurance and poorer physical health, and with feet symptoms-greater body mass index and less core stability.

Implementing Machine Learning Algorithms to Classify Postures and Forecast Motions When Using a Dynamic Chair

Many modern jobs require long periods of sitting on a chair that may result in serious health complications. Dynamic chairs are proposed as alternatives to the traditional sitting chairs; however, previous studies have suggested that most users are not aware of their postures and do not take advantage of the increased range of motion offered by the dynamic chairs. Building a system that identifies users’ postures in real time, as well as forecasts the next few postures, can bring awareness to the sitting behavior of each user. In this study, machine learning algorithms have been implemented to automatically classify users’ postures and forecast their next motions. The random forest, gradient decision tree, and support vector machine algorithms were used to classify postures. The evaluation of the trained classifiers indicated that they could successfully identify users’ postures with an accuracy above 90%. The algorithm can provide users with an accurate report of their sitting habits. A 1D-convolutional-LSTM network has also been implemented to forecast users’ future postures based on their previous motions, the model can forecast a user’s motions with high accuracy (97%). The ability of the algorithm to forecast future postures could be used to suggest alternative postures as needed.

The relationship between low back pain and the basic lumbar posture at work: a retrospective cross-sectional study

PURPOSE

This study aimed to analyze the relationship between work-related lumbar posture (sitting, standing, walking, alternating posture) and LBP in workers.

METHODS

This is a retrospective study comprising 529 records of adult workers from a database of a private company. Predominant work-related lumbar posture was classified based on time spent in each posture. A total of 22 personal, occupational, clinical, and psychosocial covariates were evaluated. LBP symptoms in the last 12 months and during the last 7 days were the outcomes of the study. The multivariate analysis model evaluated the independent relationship between the work-related lumbar posture classification and other potential exposure factors with LBP.

RESULTS

The adjusted logistic regression model indicated that predominant walking reduced the likelihood to report LBP during the last 12 months when compared to standing (OR = 0.54; 95% CI 0.30, 0.99; p = 0.048), but there is no association between work-related postures and recent LBP. The adjusted analyses also revealed an association between LBP during the last 12 months and female sex, blue-collar task, frequently feeling tiredness, pain at any other body region previous 12 months, previous LBP, and monotonous work. Recent LBP was associated with female sex, pain at any other body region last 7 days, and previous LBP.

CONCLUSIONS

Standing posture increases the likelihood to report LBP during the last 12 months when compared to walking. LBP over previous year and during the previous 7 days was associated with personal and clinical factors.

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).

Effect of a dynamic seat pan design on spine biomechanics, calf circumference and perceived pain during prolonged sitting

This study investigates the effects of a dynamic seat pan design on sitting biomechanics, perceived pain and seat movement compared to a control. Thirty male participants were recruited for two experimental sessions consisting of a 2-h sitting exposure (standardized typing task). Spine angles, back muscle activity, perceived pain and calf circumference were measured pre and post exposure. Sitting in the dynamic condition resulted in lower pain ratings (p = 0.031), decreased calf circumference (p < 0.001), lower average seat pressure (p < 0.001), and greater seat contact area (p = 0.003) compared to the control. Spine angles and low back EMG for all 6 muscles showed no significant differences between chair conditions. These results suggest this dynamic seat pan design is effective at decreasing several negative components associated with sitting for the occupant. Future work should examine the longer-term effects of dynamic office chair features in the field setting with a more generalizable population.

Prevalence, Incidence, and Factors Associated With Non-Specific Chronic Low Back Pain in Community-Dwelling Older Adults Aged 60 Years and Older: A Systematic Review and Meta-Analysis

Chronic low back pain (CLBP) is common among older adults. This systematic review aimed to summarize: (1) the prevalence and incidence of CLBP in older adults, and (2) demographic, psychological, and clinical factors positively/negatively associated with prevalence/incidence of CLBP among older adults. Four databases were searched to identify relevant publications. Ten studies (31,080 older adults) were included after being screened by 5 independent reviewers using predetermined criteria. The methodological quality of these studies was evaluated by standardized tools. The quality of evidence for all factors were appraised by modified GRADE for cohort studies. Twenty-eight and 1 factors were associated with a higher prevalence and a lower 5-year cumulative incidence of CLBP, respectively. No prognostic factor was identified. There was very limited to limited evidence that females, obesity, anxiety, depression, mental disorders, self-expectation of recovery, self-perceived health status, lifestyle (smoking, daily fluoride consumption), previous falls or lower body injury, retirement/disability due to ill health, family history of body pain, comorbidity (knee osteoarthritis, or chronic obstructive pulmonary disease with/without hypertension), weak abdominal muscles, leg pain, leg pain intensity, widespread pain, pain interference on functioning, use of pain medication, occupational exposure (driving for >20 years, or jobs involving bending/twisting for >10 years), disc space narrowing and severe facet osteoarthritis were significantly related to a higher prevalence of CLBP in older adults. However, very limited evidence suggested that intermediate level of leisure-time physical activity was associated with a lower prevalence of CLBP in older adults. Given the aging population and limited information regarding risk factors for CLBP in older adults, future high-quality prospective studies should identify relevant risk factors to help develop proper preventive and treatment strategies. PERSPECTIVE: Despite the high prevalence of non-specific chronic low back pain among older adults, there is only very limited to limited evidence regarding factors associated with a higher prevalence of chronic low back pain in this population. Given the aging population, high-quality prospective studies are warranted to address this gap.

What Psychosocial and Physical Characteristics Differentiate Office Workers Who Develop Standing-Induced Low Back Pain? A Cross-Sectional Study

This study examines demographic, physical and psychosocial factors associated with an increase in low back pain (LBP) during a one-hour standing task. A cross-sectional survey with 40 office workers was conducted. The primary outcome was pain severity during a one-hour standing task recorded every 15 min using a 100 mm Visual Analogue Scale (VAS). Participants were defined as pain developers (PD), if they reported a change in pain of ≥10 mm from baseline, or non-pain developers (NPD). Physical outcomes included participant-rated and examiner-rated trunk and hip motor control and endurance. Self-report history of LBP, physical activity, psychosocial job characteristics, general health and pain catastrophising were collected. Fourteen participants were PD. Hip abduction, abdominal and spinal muscle endurance was lower for PD (p ≤ 0.05). PD had greater self-reported difficulty performing active hip abduction and active straight leg raise tests (p ≤ 0.04). Those reporting a lifetime, 12 month or 7-day history of LBP (p < 0.05) and lower self-reported physical function (p = 0.01) were more likely to develop LBP during the standing task. In conclusion, a history of LBP, reduced trunk and hip muscle endurance and deficits in lumbopelvic/hip motor control may be important to consider in office workers experiencing standing-induced LBP.