Dynamic stability evaluation of trunk accelerations during walking in blind and sighted individuals.

BACKGROUND: Dynamic stability is a fundamental goal in standing activities. In this regard, monitoring, analysis, and interventions made to improve stability is a research topic investigated in the biomechanics of human movements. Vision has a major role to play in controlling human movement. Nonetheless, little is known about the effects of visual deprivation, especially from birth on dynamic gait stability. METHODS: The current study was conducted on 20 congenital blind and 10 sighted people (15-38 years). To evaluate the dynamic stability, descriptive data, harmonic ratio (HR), improved harmonic ratio (iHR), and root mean square (RMS), based on trunk acceleration data were measured in three axes: anteroposterior (AP), vertical (V), and mediolateral (ML) while participants walked an eight-meter straight path. RESULTS: In the comparison of blind and sighted people (eyes open), standard deviation, HR, iHR, and RMS indices were found to be significantly different in both AP and V directions. All the mentioned parameters were significantly lower in blind than in sighted participants. In the comparison of blind people and sighted ones with closed eyes, changes were observed in the maximum, range, standard deviation, and RMS only in the AP axis. In the comparison between eyes open and closed in sighted people, a significant difference was found only in the harmonic ratio of the vertical axis. CONCLUSION: Visual deprivation led to a decrease in dynamic stability parameters in the AP and V axes. Even the movement of sighted people in unchallenged conditions is dependent on visual information.

The hip joint mobilization with movement technique improves muscle activity, postural stability, functional and dynamic balance in hemiplegia secondary to chronic stroke: a blinded randomized controlled trial.

BACKGROUND: People with stroke generally experience abnormal muscle activity and develop balance disorder. Based on the important role of the proximal joints of the lower extremity in balance maintenance, hip joint mobilization with movement technique can be applied to enhance normal joint arthrokinematics. Therefore, the present study aimed to investigate the effectiveness of hip joint mobilization with movement technique on stroke patients' muscle activity and balance. METHODS: Twenty patients aged between 35 and 65 years old with chronic stroke were randomly assigned either to an experimental group (n = 10) or to a control group (n = 10). Both groups participated in a 30-minute conventional physiotherapy session 3 times per week for 4 weeks. The experimental group received an additional 30-minute's session of hip joint mobilization with movement technique on the affected limb. The muscle activity, berg balance scale, time up and go, and postural stability were measured at baseline, 1-day and 2-week follow-up by a blinded assessor. RESULTS: The experimental group showed a significant improvement in berg balance scale, time up and go, and postural stability (p ≤ 0.05). The rectus femoris, tibialis anterior, biceps femoris, and medial gastrocnemius muscles' activations of the affected limb during static balance test markedly changed along with the biceps femoris, erector spine, rectus femoris, and tibialis anterior muscles during dynamic balance test after hip joint mobilization with movement technique. The mean onset time of rectus abdominus, erector Spine, rectus femoris, and tibialis anterior muscles activity significantly decreased in the affected limb after hip joint mobilization with movement technique compared to the control group (p ≤ 0.05). CONCLUSIONS: The results of the present study suggest that a combination of hip joint mobilization with movement technique and conventional physiotherapy could improve muscle activity and balance among chronic stroke patients. TRIAL REGISTRATION NUMBER: The study was registered in the Iranian Registry of Clinical Trials (No; IRCT20200613047759N1). Registration date: 2/08/2020.

Effects of an ergonomic intervention program based on the PRECEDE-PROCEED model for reducing work-related health problems and exposure risks among emergency medical dispatchers.

OBJECTIVE: To evaluate the effectiveness of an ergonomic intervention program based on the PRECEDE-PROCEED model in terms of improving exposure risks and work-related health problems in emergency medical dispatchers. METHODS: This quasi-experimental study used an interrupted time series design. Participants were 55 employees working in an Emergency Medical Communications Center in Iran. The intervention program was based on the PRECEDE-PROCEED model and included five face-to-face training sessions and installing auxiliary equipment according to best ergonomic principles. Direct observations of the emergency medical dispatchers' working postures using the Rapid Office Strain Assessment and a survey which included a modified Nordic Questionnaire, Work Ability Score, Visual Fatigue Questionnaire, and a Behavioral Factors Questionnaire were used at three time points: baseline, 1 month post-intervention, and 3 months post-intervention. RESULTS: The modified Nordic Questionnaire showed significant reductions in pain intensity scores for neck, lower back, knee and ankle after the ergonomic intervention program. In addition, there were considerable post-training improvements in behavioral factors (knowledge and enabling factors) and working postures. No significant changes were observed in Work Ability Scores, or visual symptoms. CONCLUSIONS: An ergonomic intervention program based on a systematic framework such as the PRECEDE-PROCEED model and on-site interventions can be effective in improving and enhancing the working conditions of emergency medical dispatchers. Therefore, it is suggested that ergonomic interventions be implemented based on standard and valid behavioral change models such as PRECEDE-PROCEED model in other work environments in which musculoskeletal pain and digital eye strain are common.

Development and validation of a Nurse Station Ergonomics Assessment (NSEA) tool.

BACKGROUND: Nurse stations are one of the primary units for supporting effective functioning of any hospital. They are important working environments that demand adherence to known ergonomic principles for the well-being of both staff and patients. The aim of this study was to develop a psychometrically tested tool for the assessment of the ergonomic conditions of nurse workstations in hospitals. METHODS: Ten hospitals, with a total of 133 nurse stations participated in this mixed-methods research. The domains and items of the tool were developed based on a literature review, an experts' panel, and interviews with nurses. RESULTS: The final nurse station ergonomic assessment (NSEA) tool has good psychometric properties. Validity was assessed by face validity and content validity. Reliability was evaluated using inter-rater agreement and test-retest reliability analyses with a four-week interval between assessments. The NSEA is comprised of 64 items across eight domains: layout and location (7 items), workspace (11 items), security-safety (5 items), environmental conditions (8 items), counter (8 items), chair (13 items), desk (9 items), and monitor (3 items). CONCLUSIONS: The NSEA adds to the literature a tool for managers to ensure they comply with legal requirements and support best practice for those working on hospital wards. The NSEA can be used to identify challenges for healthcare professionals who use nurse stations and support the execution of targeted interventions to improve human-environment interactions.

A New Clustering Method for Knee Movement Impairments using Partitioning Around Medoids Model.

BACKGROUND: The movement system impairment (MSI) model is a clinical model that can be used for the classification, diagnosis, and treatment of knee impairments. By using the partitioning around medoids (PAM) clustering method, patients can be easily clustered in homogeneous groups through the determination of the most discriminative variables. The present study aimed to reduce the number of clinical examination variables, determine the important variables, and simplify the MSI model using the PAM clustering method. METHODS: The present cross-sectional study was performed in Shiraz, Iran, during February-December 2018. A total of 209 patients with knee pain were recruited. Patients' knee, femoral and tibial movement impairments, and the perceived pain level were examined in quiet standing, sitting, walking, partial squatting, single-leg stance (both sides), sit-to-stand transfer, and stair ambulation. The tests were repeated after correction for impairments. Both the pain pattern and the types of impairment were subsequently used in the PAM clustering analysis. RESULTS: PAM clustering analysis categorized the patients in two main clusters (valgus and non-valgus) based on the presence or absence of valgus impairment. Secondary analysis of the valgus cluster identified two sub-clusters based on the presence of hypomobility. Analysis of the non-valgus cluster showed four sub-clusters with different characteristics. PAM clustering organized important variables in each analysis and showed that only 23 out of the 41 variables were essential in the sub-clustering of patients with knee pain. CONCLUSION: A new direct knee examination method is introduced for the organization of important discriminative tests, which requires fewer clinical examination variables.

The Comparison of Genetic Factors Influences on Physical Activity and Health between Classical Medicine and Iranian Traditional Medicine.

BACKGROUND: Different factors, especially genetic, effect individual attitude to regular physical activity in Iranian traditional medicine. It was believed that individual physical activity attitude is affected by Mizaj too. Our aim was to conduct a comparative revision and evaluation of the effect of genetic factors on physical activity in classic medicine and Iranian traditional medicine. METHODS: In this study, we reviewed Persian resources in the research center of traditional medicine at Shiraz University of Medical Sciences. We also evaluated the texts on physical activity and genetics in PubMed and Google Scholar. RESULTS: The results of classical medicine revision showed the effect of especial genes on obesity and sedentary behavior. It is also derived from Iranian traditional medicine resources that physical activity and sedentary behavior is affected by individual Mizaj. CONCLUSION: The results showed that those with hot and cold Mizaj have different genetic potentials in sedentary behavior and physical activity. Such categorization would be helpful in identifying illnesses due to sedentary life in special groups of people. It would also allow designing dedicated treatment for each person.

Assessment of functional parameters and comfort of a new computer mouse as compared with other types of input devices.

BACKGROUND: This study was conducted to assess functional parameters and comfort of a new computer mouse (Ergomice) as compared with three other input devices. MATERIALS AND METHODS: Functional parameters (i.e., task completion time and error rate) of each device were assessed by 10 participants using standardized software based on Standard No. ISO 9241-9:2000. Comfort evaluation was also undertaken for each device using the visual analogue scale technique. Statistical analysis including the Wilcoxon signed-rank test and the Friedman test was performed using SPSS version 16. RESULTS: The functional parameters of the standard mouse were better than those of the other devices. However, no significant difference was observed between this mouse and Ergomice. Overall comfort evaluation showed that the standard mouse and Ergomice were more comfortable to work with. The comfort level of hand/wrist posture in the Ergomice was higher than that of the other three devices. CONCLUSION: The design features of Ergomice could improve its functional properties. Hand/wrist posture comfort of Ergomice was judged to be high compared with that of the other devices.

Effect of dry needling on pain and central sensitization in women with chronic pelvic pain: A randomized parallel-group controlled clinical trial.

Chronic pelvic pain (CPP) is a debilitating problem in women with clear evidence of myofascial dysfunction. It seems that Myofascial trigger points (MTrPs) contribute to the development of central sensitization (CS). This study aimed to investigate the effect of dry needling on pain and CS in women with CPP. Thirty-six women with CPP participated in this randomized controlled clinical trial and randomly assigned into three groups: dry needling group (DNG), placebo needling group (PNG) and control group (CG). The DNG received five sessions of DN using the "static needling", the PNG received non-penetrating method, and the CG did not receive any intervention. Assessment of outcomes including central sensitization inventory (CSI), short-form McGill pain questionnaire (SF-MPQ), electroencephalography (EEG), conditioned pain modulation (CPM), salivary cortisol concentration, 7-item general anxiety disorder scale (GAD-7), pain catastrophizing scale (PCS), and SF-36 questionnaire was performed pre-intervention, post-intervention, and three months post-intervention by a blind examiner. The result showed a significant group-by-time interaction for CSI, SF-MPQ, and PCS. There was a significant decrease in CSI score in post-intervention and three-months post-intervention compare to pre-intervention in the DNG and PNG. SF-MPQ-PPI score in DNG significantly decreased post-intervention. PCS-Total score decreased significantly post-intervention in DNG and PNG. No significant group-by-time interactions were observed for other variables. EEG results showed regional changes in the activity of frequency bands in both eye closed and eye open conditions. It seems that DN can affect central pain processing by removing the source of peripheral nociception. Trial registration: Iranian Registry of Clinical Trials (IRCT20211114053057N1, registered on: December 03, 2021. https://irct.behdasht.gov.ir/search/result?query=IRCT20211114053057N1).

Respiratory Function Assessment through Kinematic Analysis of Chest Wall Movements: Effects of Position and Gender.

Background: The effect of position and gender on chest movements and respiratory volumes is controversial and investigated in only a few studies. Objective: This study aimed to investigate the effects of position and gender on the breathing pattern during four different positions in healthy individuals. Material and Methods: In this cross-sectional study, twenty-eight (14 males, 14 females) healthy individuals participated aged 20-45 years. The optoelectronic plethysmography (OEP) method was used for the three-dimensional evaluation of chest wall motions and the compartmental analysis of the breathing pattern in supine, sitting, standing, and active straight leg raised (ASLR) positions. Volume changes in different parts of the chest wall were also measured. Results: Position affected total and compartmental respiratory volumes in both genders. Respiratory volumes decreased in the supine position compared to sitting and standing. Total and abdominal respiratory volumes also decreased in females when comparing supine positions with the ASLR. A higher pulmonary rib cage contribution was identified in females, and males exhibited higher abdominal rib cage volume compared with females. Conclusion: The breathing pattern was affected by position and gender, and the respiratory volumes increased in more upright positions, perhaps due to a greater gravitational load. The ASLR decreases the respiratory volume, which is probably due to increased postural demand.

Development of an Ergonomic, Portable, Climber-Propelled Date Tree Climbing Device.

In the most of main date fruit producer regions, including Iran, date palm crown access operation is still performed traditionally. The date plantation workers need to climb date trees. This may cause an unsafe condition, which increases the risk of fall from height. It is also associated with ergonomic and health problems. The present study aimed to develop a date tree climber device (DTCD) covering all aspects of safety, ergonomics and efficiency. A primary model of the DTCD was structured and modified based on a review of existing devices, a field investigation and an unstructured interview with 20 farmworkers. Participants rated their comfort, perceived pain and discomfort as well as exertion levels when using the DTCD compared to a traditional device (Parband). In total, eight key elements were suggested for the desired device. More than 60% of the participants reported that the DTCD was comfortable/very comfortable compared to Parband. Additionally, DTCD could significantly reduce the pain and discomfort of the back (p < .001), knees (p = .001) and Ankles/feet (p = .01). However, no significant difference was found between devices when the physical exertion was compared through Borg's RPE scale and heart rate analysis. The results of regression analysis showed that the DTCD users perceived lower exertion as the body weight increased (ß = -0.18, p = .013). The signs of musculoskeletal disorders, pain and discomfort were strongly reduced among DTCD users and safety aspects improved, generally by reducing discomfort and physical exertion.

The Use of Cluster Analysis by Partitioning around Medoids (PAM) to Examine the Heterogeneity of Patients with Low Back Pain within Subgroups of the Treatment Based Classification System.

Background: Current evidence in low back pain (LBP) focuses on population averages and traditional multivariate analyses to find the significant difference between variables. Such a focus actively obscured the heterogeneity and increased errors. Cluster analysis (CA) addresses the mentioned shortcomings by calculating the degree of similarity among the relevant variables of the different objects. Objective: This study aims to evaluate the agreement between the treatment-based classification (TBC) system and the equivalent 3 cluster typology created by partitioning around medoids (PAM) analysis. Material and Methods: In this cross-sectional study, a convenient sample of 90 patients with low back pain (50 males and 40 females) aged 20 to 65 years was included in the study. The patients were selected based on the 21 criteria of 2007 TBC system. An equivalent 3 cluster typology (C3) was applied using PAM method. Cohen's Kappa was run to determine if there was agreement between the TBC system and the equivalent C3 typology. Results: PAM analysis revealed the evidence of clustering for a C3 cluster typology with average Silhouette widths of 0.12. Cohen's Kappa revealed fair agreement between the TBC system and C3 cluster typology (Percent of agreement 61%, Kappa=0.36, P<0.001). Selected criteria by PAM analysis were different with original TBC system. Conclusion: Higher probability of chance agreement was observed between two classification methods. Significant inhomogeneity was observed in subgroups of the 2007 TBC system.

Evaluation of Contralateral Limb Cross Education and High-Frequency Repetitive Transcranial Magnetic Stimulation on Functional Indices of the Affected Upper Limb in Subacute Phase of Stroke.

Background: Stroke is one of the causes of long-term morbidity. Despite rehabilitation strategies, most survivors live with motor deficits in the upper limbs. Objectives: The aim of the study was to compare the effect of contralateral cross education (CE) and high-frequency repetitive magnetic stimulation (HF-rTMS) on the function of upper extremity in subacute phase of stroke. Methods: Forty patients were randomly assigned into 4 groups. Group "A" received physical therapy (PT) for 10 sessions, 3 times per week. Group "B" received PT and HF-rTMS as follows: stimulation of 20 Hz for 5 s, intertrain interval for 50 s, 20 trains, 2000 pulses at 90% resting motor threshold, and conventional PT. Group "C" was treated with CE and PT. In group "D," HF-rTMS, CE, and PT were administered. Results: Significant differences were found in the Fugl-Meyer scale between "A" and "C" (P = 0.01), "A" and "D" (P = 0.02), and "B" and "C" groups (P = 0.01). In the box-block test, there were significant differences between "A" and "B" (P = 0.01), "A" and "C" (P < 0.001), "B" and "D" (P = 0.001), and "B" and "C" groups (P = 0.01). Statistical differences were observed in grip strength between "A" and "B" (P = 0.01) and "A" and "C" groups (P = 0.02). Conclusions: It is suggested that clinicians select the therapeutic methods in line with their expected goal. When the goal is to improve upper extremity function, CE+PT could be more effective than HF-rTMS+PT. Also, CE+PT and HF-rTMS+PT were more effective than CE+HF-rTMS+PT at improving grip strength. Therefore, combining several methods would not always lead to better results.

Recommended maximum holding time of common static sitting postures of office workers.

Objectives. A posture maintained for a long period can be harmful to the health of office workers. This study aimed to estimate the recommended ergonomic duration for maintaining different sitting postures. Methods. Forty healthy male and female students participated in this experiment designed to measure perceived discomfort caused by maintaining common static sitting postures of office workers in a simple ergonomic set-up for 4 min. The Borg CR10 scale was given to the participants to assess the discomfort in different body parts, before and after each experiment. Based on the mean group discomfort level of 2, the recommended holding time of each posture was estimated. Results. The recommended holding time and its discomfort score for each studied posture were tabulated. The shortest holding time of a posture was obtained for the moderate neck flexion (1.61 min), and the longest holding time was obtained for a leg posture with 90° knee flexion (6.45 min). Conclusions. The recommended holding time in this study may help to assess the risk of musculoskeletal disorders (MSDs) in office workers and train the individuals involved in office tasks in proper sitting behavior.

Assessment of the effects of white cane variables on step symmetry of blind individuals.

BACKGROUND: Step symmetry is an important feature of human gait and is often regarded as a key index of healthy individuals' walking. This study evaluated the effects of height, white cane technique, and cane tip on symmetrical gait in blind individuals. MATERIALS AND METHODS: Twenty blind and ten sighted subjects, aged 15-38 years, participated in this study. The harmonic ratio (HR) and improved HR (iHR) were measured by trunk accelerometer as gait symmetry index in three axes: anteroposterior (AP), vertical, and mediolateral of the body. These parameters were measured in the sighted group in open-eye conditions and in the blind group in five experimental conditions with different two heights (standard and long), two tips (pencil and roller), and two techniques (two-point touch and constant contact) of white cane when they walked in the 6-m path. RESULTS: There was a significant difference between HR and iHR of the blind and sighted group, which indicates a significant reduction of symmetry loss in the blind group. Among the five different conditions studied in the group of blind people, an increase was observed in the HR and the iHR on the AP axis during the application of a standard cane with a roller tip, which indicated an increase in symmetry. CONCLUSION: Based on the results, a long cane with a pencil tip and a standard cane with a roller tip in the constant contact technique can increase step symmetry.

Knee Extension Exercise Effects on Physiological and Psychophysical Performance: Normal Weight Versus Obese Office Workers.

BACKGROUND: Knee extension exercise is useful and practical for obese and overweight people as this form of exercise is effective in minimizing body weight loading on joints and improving the body's physiological function. This study aimed to compare the physiological and psychophysical parameters of office workers while computer-based working in an active workstation equipped with an active footrest (AFR) prototype with a mechanism for performing knee extension exercises in a sitting position, and also to compare the physiological and psychophysical parameters among normal-weight and obese office workers. METHODS: In this quasi-experimental study, the physiological parameters of heart rate (HR) and energy expenditure (EE) (measured with the Fitbit Charge HR smartwatch) were measured in two cross-over random sessions for 32 office workers (16 normal-weight and 16 obese) aged 28 to 50 years (M = 42.72, standard deviation [SD] = 4.37) while performing office tasks in sitting and active workstations (equipped with AFR). Perceived physical exertion, comfort, fatigue, and liking were also measured by rating the participants. FINDINGS: Short-term activity of the participants with AFR performing computer tasks significantly improved physiological and psychophysical parameters compared with the participants in sitting workstations. However, there was no significant difference in the effect of AFR on physiological and psychophysical parameters between normal-weight and obese participants. CONCLUSIONS/APPLICATION TO PRACTICE: Given the significant increase in EE and HR resulting from exercise with AFR compared with the conventional workstation, the use of AFR can help office workers achieve the minimum standard of physical activity at their workplace.

Cognitive and skill performance of individuals at sitting versus standing workstations: a quasi-experimental study.

Objectives. This study aimed to assess cognitive and skill performance at sitting and standing workstations among students from Shiraz University of Medical Sciences. Methods. Forty students (20 females and 20 males) participated in this quasi-experimental study. Tests were performed among randomly selected participants over two consecutive days: day 1, the Beck depression inventory and Beck anxiety inventory were used to assess the severity of depression and anxiety in the study participants, respectively, and Raven's general intelligence test was used to measure intelligence quotient; day 2, five performance assessment tests (cognitive performance assessment tests 'n-back', 'Stroop' and 'advanced reaction time'; skill performance assessment tests 'two-arm coordination' and 'Purdue pegboard') were randomly selected and presented to individuals at each workstation (sitting and standing workstations). At the end of each sitting and standing position, the comfort of the workstation was measured using a visual analog scale. Results. No statistically significant difference was shown between sitting and standing positions in terms of 'n-back', 'Stroop', 'advanced reaction time', 'two-arm coordination' and 'Purdue pegboard'. Participants were more comfortable in sitting positions and more easily distracted in standing positions. Conclusions. Sitting and standing positions had no significant effects on participants' cognitive and skill performance.

Knee impairments: Comparison between new clinical classification by cluster analysis and movement system impairment model.

BACKGROUND: Although Movement System Impairment (MSI) model classifies patients with knee impairments, it has some limitations. This study compares MSI model with a new Partitioning Around Medoids (PAM) model in knee pain patients. METHODS: In this cross-sectional study, knee movement impairments (signs) and symptoms. (pain) of 200 patients were studied in eight different functional positions. After modification of impairments, the examinations were repeated to record the changes in symptoms. The patients were then classified based on the signs and symptoms firstly by MSI model and secondly using PAM clustering by R software. RESULTS: PAM model has a similar acceptable grouping compared to MSI because most patients are in 4 similar categories in both methods: valgus, varus, hyperextension and hypomobility. However, due to low discriminative power of the tests used for finding hypermobility and patellar dysfunctions, these sub-clusters are absent in PAM model. Instead, two new sub-clusters of self-management and valgus with hypomobility were found. Most importantly, the PAM model sorted the signs and symptoms based on their discriminative power and eliminated trivial tests so that the therapist can classify patients more quickly by performing clinically relevant tests. CONCLUSION: The new PAM method can be advantageous for therapists since it defines the importance of signs over symptoms in examination, prioritizes examination tests, and outlines tests with lower discriminative power. In PAM model, patients in the hypermobility and patellar subgroups of MSI model merged into other sub-clusters due to low discriminating power of their characteristics.

Investigating the effect of background music on cognitive and skill performance: A cross-sectional study.

BACKGROUND: Existing studies on the impact of background music in the workplace have reported varying results, from improving production and performance to being known as an annoying factor. Given the lack of evidence of the background music influence on the cognitive factors in the work place in previous studies and the lack of study on the effect of background music on skill performance when gender and personality type is considered, research in this area seems necessary. OBJECTIVE: The purpose of the present study is to investigate the influence of background music on cognitive and skill performance in the work place with regard to gender and personality type. METHODS: This study was conducted with the participation of 52 students (26 males and 26 females) aged between 18-30 years old. Sustained attention, working memory, fine finger and gross manual dexterity skills and personality type were assessed. Participants were randomly tested once when being exposed to classical instrumental music and once again when faced with complete silenceRESULTS:Playing background music improved students working memory but had no significant effect on sustained attention. Music also improved skill performance.Overall, memory performance and fine finger dexterity were found significantly better in extroverts when compared to introverts during playing background music. CONCLUSION: Background music improves working memory and speeds up performance in skill tasks, however the role of personality type in influencing background music on cognitive and skill performance needs further investigation.

Investigation of office workers' sitting behaviors in an ergonomically adjusted workstation.

Objectives. Common ergonomic office workstations are designed for a few optimum postures. Nonetheless, sitting is a dynamic activity and the ideal sitting posture is rarely maintained in practice. Therefore, the present study aimed to investigate the sitting behavior of office workers in an actual working environment using ergonomically adjusted workstations to examine whether they promote maintaining appropriate sitting postures. Methods. Sitting behaviors (frequency of postures and position changes in different body parts) were explored among 26 office workers during a 60-min sitting duration, using the posture recording and classification method developed by Graf et al. The rapid upper limb assessment (RULA) method was also used to assess postural load. Then, the results of the RULA method were compared with the results from investigating the sitting behavior of office workers. Results. Common ergonomic workstations were effective in eliminating some awkward postures. However, some important risk factors such as holding postures with an inappropriate lumbar spine curve (86% of the observations) and maintaining a posture for a long time (for 7-12 min) were observed in the participants' sitting behaviors, while they were neglected in the RULA method. Conclusions. The common ergonomic workstations could not guarantee the users' appropriate sitting behaviors.

Adverse Effects of Sit and Stand Workstations on the Health Outcomes of Assembly Line Workers: A Cross-sectional Study.

Introduction: Sitting and standing workstations can affect individual's health outcomes differently. This study aimed to assess the effects of sit and stand workstations on energy expenditure and blood parameters, including glucose and triglyceride, musculoskeletal symptoms/pain and discomfort, fatigue, and productivity among workers of assembly line of a belt factory. Methods: This cross-sectional study was conducted on 47 male assembly line workers (24 workers in sitting workstation and 23 workers in standing workstation) with at least one year of working experience. Data were gathered via demographic/occupational characteristics, Fitbit system, medical records, the Persian version of the Nordic Musculoskeletal Questionnaire (P-NMQ), the Persian version of the Numeric Rating Scale (P-NRS), the Persian version of the Swedish Occupational Fatigue (P-SOFI), and Persian version of the Health and Work Questionnaire (P-HWQ). Results: The results showed that there were no statistically significant between the demographic/occupational details of the participants in sitting and standing groups, except work experience. The findings of the present study revealed that the energy expenditure, and blood glucose/triglyceride there are not statistically differences between sitting and standing groups. In addition, the prevalence of musculoskeletal symptoms in the neck, lower back, knees, and ankles/feet in standing group was significantly higher than the sitting group. The means of severity of discomfort/pain in all body regions were significantly higher in standing group compared to other group. Generally, occupational fatigue was higher among the standing group compared to sitting group. About productivity, the 'concentration/focus' and 'impatience/irritability' subscales in sitting group were higher than the standing group. Contrariwise, other subscales of the productivity, including 'productivity', 'supervisor relations', 'non-work satisfaction', 'work satisfaction' in the standing group were higher than the sitting group. Conclusions: To reduce the adverse effects of sitting and standing workstations on individual's health outcomes, planning to use sit-stand workstations is recommended.