Sitting Positions Research Articles

The Association between Knowledge and Attitude of Ergonomic Sitting Position to Sitting Posture and Duration among Medical Students

Introduction: Medical students may spend more time sitting and learning. However, ignorance of the ergonomic sitting position and long sitting duration can lead them to an incorrect sitting position and high sedentary activity. Thus, this study investigated the association between knowledge and attitude towards ergonomic sitting position to sitting duration and posture among medical students. Methods: This cross-sectional study involved 30 students of the School of Medicine and Health Sciences, Atma Jaya Catholic University of Indonesia. Data were obtained using a questionnaire. Questionnaires were distributed to participants and consisted of 2 parts, the first part included personal data, while the second part contained knowledge, attitude, and practice (sitting duration and posture). Fisher’s exact test and Fisher-Freeman-Halton were applied. The confidence interval was 95%, and the significance level (alpha) was 0.05. Results: 23.3% of the participants have good knowledge about ergonomics sitting position, 40% have adequate knowledge, and 56.7% have a positive attitude towards ergonomics sitting position. 60% of the participants spent sitting time more than 8 hours a day, and 43.3% of the participants had a straight sitting posture. Fisher’s test showed no significant association between ergonomic knowledge and chair sitting duration (p= 0.933) and ergonomic attitude and chair sitting duration (p= 0.711). Fisher-Freeman-Halton exact test showed no significant association between ergonomic knowledge and sitting posture on a chair (p= 0.699) and ergonomics attitude and chair sitting posture (p= 1.000). Conclusions: There was no association between knowledge of ergonomics sitting position with sitting duration and sitting posture and attitude of ergonomics sitting position with sitting duration and sitting posture. Keywords: knowledge – attitude - sitting duration - sitting posture - sitting ergonomics

The relationship between sitting posture and neck pain incidence in educational staff at the Universitas Muhammadiyah Surakarta

Background: While working, many educational staffs complain about musculoskeletal problems due to sitting for an extended periods. Sitting posture affects neck pain because the pressure on the intervertebral disc is twice as great when sitting compared to standing. A good sitting posture is to relax momentarily because the muscles experience tension, reducing neck pain.
 Methods: This cross-sectional study was carried out in December 2022 with a population of Educational Staff at the Universitas Muhammadiyah Surakarta who met the inclusion and exclusion criteria. The sampling technique in this study was purposive sampling, and 84 samples were obtained. The research data were collected by broadcast email, WhatsApp messages, and direct distribution to staff. Data were analyzed with SPSS 25.0 to determine the correlation between sitting posture and the incidence of neck pain.
 Results: The Spearman Rho test analysis showed a p-value<0.05, indicating a significant relationship between sitting posture and neck pain among educational staffs at the Universitas Muhammadiyah Surakarta. In contrast, the correlation coefficient showed 0.452, indicating a moderate correlation between sitting posture and neck pain. The relationship was in positive value so that the level of neck pain was reduced.
 Conclusion: The sitting posture is related to neck pain incidence among academic staff at the Universitas Muhammadiyah Surakarta. This study has an excellent impact on observing the factors contributing to neck pain incidence in academic staff at the Universitas Muhammadiyah Surakarta. In contrast, the further study requires finding the other aspects of neck pain in teams to minimize the occurrence of complaints in the future.

Reliability of Ultrasound Measurements of the Lumbar Multifidus and Transversus Abdominis Muscles during Lying and Unstable Sitting Positions in Individuals With and Without Chronic Low Back Pain

The reliability studies are limited to support ultrasound usage during dynamic conditions; for example, unstable sitting position. This study aims to examine the reliability of ultrasound measurements of the lumbar multifidus and transversus abdominis during lying and unstable sitting positions in individuals with chronic low back pain (CLBP) and asymptomatic individuals considering abnormal lumbar lordosis. In this observational study, intrarater within-day and between-day reliability of muscle thickness and contraction ratio of the lumbar multifidus and transversus abdominis muscles were assessed using ultrasound imaging. In total, 40 participants (27 with CLBP, 13 asymptomatic individuals) with abnormal lumbar lordosis were recruited. The degree of lumbar lordosis has been measured by a flexible ruler. The muscle thickness was assessed at lying and sitting on a gym ball for both muscles in three sessions. Both groups had well to high ICCs of thickness measurement and contraction ratio in the transversus abdominis and lumbar multifidus muscles during both static (ICC=0.71-0.99) and semi-dynamic conditions (ICC=0.73-0.98). The standard error of measurements and minimal detectable changes were rather small in both groups. Ultrasound imaging is a highly reliable method to assess muscle thicknesses and contraction ratio of the transversus abdominis and lumbar multifidus during different conditions, even in patients with CLBP and abnormal lumbar lordosis.

Faktor-Faktor yang Berhubungan dengan Keluhan Subjektif Low Back Pain pada Penjahit di Pasar Istana Anak-Anak Kota Jambi Tahun 2022

Sewing is one of the risky jobs to experience low back pain (LBP) this is due to working with long sitting and non-ergonomic work positions. The Jambi City Children's Palace Market is the central tailor in Jambi City. The results of the observation showed that from 10 tailors, 7 experienced pain in the lower back when sewing. The purpose of the study was to determine the factors associated with complaints of LBP on tailors at the Children's Palace Market. The study used a cross sectional design. The research was conducted at the Istana Children's Market in Jambi City on 10-31 May 2022. The research population was all tailors at the Istana Anak Market. The research sample was 30 tailors at the Children's Palace Market in Jambi City. The research instrument was a questionnaire and RULA. Data collection techniques using interviews and observations of respondents' work attitudes. Data were analyzed using chi square test. As many as 53.3% of respondents have complaints of low back pain, 53.3% of respondents work with high-risk work attitudes, 60.0% of respondents work with risky work durations and 63.3% of respondents have long tenures. The results of the bivariate analysis showed that there was a relationship between work attitude (p=0.000) and tenure (p=0.011) with complaints of low back pain in tailors at the Children's Palace Market, Jambi City. There is no relationship between work duration (p-0.159) and complaints of low back pain in tailors at the Children's Palace Market, Jambi City.

Musculoskeletal complaints and associated factors in school children aged between 6 and 13 years in Istanbul during the COVID-19 pandemic: A cross-sectional study.

Following the first COVID-19 cases in Turkey, face-to-face education was ceased after March 16, 2020 until the end of the educational year (i.e. June 19, 2020) and education was substituted remotely due to confinement. This study aims to investigate the frequency of musculoskeletal complaints in school-age children and associated risk factors including reduced physical activity, increased screen time and poor ergonomics conditions in school-age children during the pandemic. This cross-sectional study included parents or guardians of 960 students aged between 6-13 years old with a non-randomized sampling. A survey was administered consisting of 65 items related with sociodemographic characteristics of the children and family, online education hours, technological device(s) used, screen time, type of physical activity, presence of musculoskeletal problems and poor ergonomics conditions such as incorrect sitting posture. Logistic regression results demonstrated that age, excess weight gain, total daily screen time, smartphone use, incorrect sitting posture were associated with musculoskeletal complaints. The long-term closure of schools due to the pandemic may have led to an increase in musculoskeletal complaints in 6-13 years old children, based on the factors identified in this study, which were excess weight gain, increased screen time and incorrect sitting posture. These findings might help education and health authorities to develop strategies to improve musculoskeletal health of children especially in emergencies such as the pandemic.

Hole Matrix Mapping Model for Partitioned Sitting Surface Based on Human Body Pressure Distribution Matrix.

(1) Objective: The objective of this study was to experimentally obtain the ideal pressure distribution model of buttock and thigh support for office workers in forward-leaning and upright sitting postures, reproduce the support provided by mesh materials with elastic materials, and propose an effective seat design scheme to improve the comfort of office workers. (2) Method: Based on the seven most popular mesh chairs on the market, pressure distribution experiments, and the fuzzy clustering algorithm, the relatively ideal body pressure distribution matrices were generated for office workers under two common sitting postures, and the corresponding partitioned sitting support surfaces were obtained. A prototype chair was created and validated by combining the ergonomics node coordinates and the physical properties of the materials. (3) Result: An ideal support model of four zones was constructed, and prototype pads were designed and produced according to this model. Subjects were recruited to test the ability of the prototypes to reproduce the ideal pressure distribution maps. (4) Conclusion: The four-zone ideal support model is capable of effectively representing the buttock and thigh support requirements in forward-leaning and upright sitting postures, and it is useful for the development of related products. Studying sitting postures and pressure values generated by different activities of office workers will help to refine the needs of office personnel and provide new ideas for the design of office chairs.

Improving Work Attitudes And Assistive Devices Can Reduce Subjective Complaints And Increase The Productivity Of Weavers

Gringsing weaving products is a part of handicraft or home industry. They are still confessed at present and produced by simple technology with hand in hand. This activity as a business of income from the most of women in Tenganan Pegringsingan Village of Manggis Sub District, Karangasem Regency. A work attitude with no planned well and they do not use a tool instruments for helping then working correctly, it is caused a subjective complaints of the workers so the production is not maximally and will cause the productivity of the workers come down. Woven products workers is required a carefulness and neatness of the workers, with long sitting posture on the flour covered by something material. It is not aware of this problem in to the anatomy and physiology of the workers and they will have a lot of complaint, sick, or pain on their next, hand, low back, anus, thigh, eyes. It is caused static work load frequently, so that they will be to come a decrease activity and low motivations, it’is activity and the work is not done efficient and effective. The variable that is measured in this study is decrease workload, subjective complaint, work efficiency (long work), and work productivity. The research has been studied to the sixteen weaving workers that were chosen without rules with treatment by subject program with cross over design, its analyses unit considering group variance. It has been intervened by work attitude with supporting tool for instant ‘peliper, tingklik, por (supported by sponge), barble, and using eyes glasses and group workers. This study is analyzed by t-paired, and there is a significant work load reduction (p<0.005), which is the pulse of the workers come down from 89,62 beats per minutes to be 82,56 beats per minutes (±5,60) in the same of the light work load category. The subjective complaints of the work load come down showed significant value (p<0.005) that is from Nordic Body Map score 56,92 (16.14) to be 28.86 (7.32). By the efficient work 7 hours a day with support tools, it is to be come the productivity increase (0,34%) and work productivity (7,9%) significantly (p<0.005).

Visual Comfort and Discomfort in Public Boarding Secondary Schools in Nairobi City County, Kenya

Indoor light quality is the intensity and amount of illumination of interior spaces. Technological developments have led to the utilisation of artificial natural light. Illumination is crucial in the visibility of tasks. Quality of light can influence the visual comfort and ocular health of the students. Although Kenya lacks lighting standards for schools, ISO and CIE provide international guidelines on optimal illumination for various facilities. This study was conducted on public boarding secondary schools in Nairobi City County to assess the visual comfort or discomfort of students in classrooms. The study utilised a cross-sectional descriptive study design. Four hundred twenty-three students were randomly sampled from 8 schools. Illumination levels were measured in 38 classrooms using a calibrated Benetech GM1010 light metre and compared to levels recommended by ISO and CIE. A self-administered semi-structured questionnaire was used to collect data on students’ visual comfort or discomfort. Data was analysed using SPSS version 23. Descriptive data were analysed using frequencies, while inferential data were analysed using chi-square. The study established that 15% of the respondents experience visual comfort during the day, 13.5% at night, and 12.7% both day and night. Fourteen classrooms achieved the recommended illumination level at 7:30, 20 at 13:00 hours, and 10 at 18:00 hours. Recorded levels ranged from 56.71 lux to 1289.93 lux. The study found a statistically significant association between visual comfort and factors such as existing eye problems, presence of blinds or curtains, number of windows, presence of whiteboards, classroom orientation and student sitting positions. The study recommends that public secondary schools need to ensure quality indoor illumination in their facilities to enhance the visual comfort of students in learning facilities.

Maternal Haemodynamic Effects of Spinal Anaesthesia using Hyperbaric Bupivacaine in Sitting and Lateral Position for Caesarean Section - A Comparative Study

Maternal Haemodynamic Effects of Spinal Anaesthesia using Hyperbaric Bupivacaine in Sitting and Lateral Position for Caesarean Section - A Comparative Study

Intra- and interrater reliability of belt-stabilized hand-held dynamometer in scapular protraction strength tests in individuals with shoulder pain

PurposeScapular protraction strength can be evaluated using a hand-held dynamometer (HHD). However, it is necessary to measure the reliability of HHD in individuals with shoulder pain and to minimize the limitations related to the evaluator and the low methodological quality cited in previous studies. This study assessed, with methodological enhancement, the intra- and interrater reliability of belt-stabilized HHD in the assessment of scapular protraction strength in individuals with shoulder pain. MethodFifty individuals with unilateral symptoms of subacromial pain syndrome (20 men, aged 40.5 ± 15.3 years) were evaluated in two sessions using the belt-stabilized HHD for maximum isometric strength of scapular protraction with the individual in the sitting and supine positions. Reliability values were obtained using the intraclass correlation coefficient with the standard error of measurement (SEM and %SEM) and the minimal detectable change (MDC). ResultsThe intra- and interrater HHD reliability were excellent for all measurements ranging from 0.88 to 0.96 (SEM = 2.0–4.0 kg; %SEM 12 to 17; MDC = 6–11 kg). ConclusionBelt-stabilized HHD is reliable for the assessment of scapular protraction strength in individuals with subacromial pain syndrome in both the sitting and supine positions.

Ergonomic Analysis of Factors Causing Musculoskeletal Disorders (MSD) in Heavy Vehicle Drivers

Driving comfort is important for any class of vehicle drivers. Seating comfort is very important for drivers who are undergoing extended period of driving and its associated side effects include higher risk of back problems, discomfort in neck, shoulder and thighs. A good sitting position and correct posture are important for drivers to reduce various work related injuries. There are several occupational risk factors that may affect the work performance of heavy vehicle drivers that may lead to health issues. One of these issues is the driver’s exposure to Musculoskeletal Disorders (MSD). MSDs are injuries and disorders that affect the human body's movement or musculoskeletal system. This is due to the fact that heavy vehicle drivers are often exposed to vibration, prolonged sitting and other postural factors. Some are related to the actual driving task, traffic situation, individual variability and cabin layout. The musculoskeletal disorders are mostly associated with work postures and movements, repetitiveness and pace of work, force of movement, vibration, temperature, workplace layout and monotonous tasks. And these mentioned risk factors may affect not only the health of the heavy vehicle drivers but may also cause related road accidents. In order to determine the occupational risk factors, a study is required to identify the current condition of heavy vehicle drivers in relation to major risk factors. Furthermore, this study aims to determine the significant factors affecting the occurrence of musculoskeletal disorders using statistical analyses.

Multi-Mode Electric Wheelchair with Health Monitoring and Posture Detection Using Machine Learning Techniques

Patients with cognitive difficulties and impairments must be given innovative wheelchair systems to ease navigation and safety in today’s technologically evolving environment. This study presents a novel system developed to convert a manual wheelchair into an electric wheelchair. A portable kit has been designed so that it may install on any manual wheelchair with minor structural changes to convert it into an electric wheelchair. The multiple modes include the Joystick module, android app control, and voice control to provide multiple features to multiple disabled people. The proposed system includes a cloud-based data conversion model for health sensor data to display on an android application for easy access for the caretaker. A novel arrangement of sensors has been applied according to the accurate human body weight distribution in a sitting position that has greatly enhanced the accuracy of the applied model. Furthermore, seven different machine learning algorithms are applied to compare the accuracy, i.e., KNN, SVM, logistic regression, decision tree, random forest, XG Boost, and NN. The proposed system uses force-sensitive resistance (FSR) sensors with prescribed algorithms incorporated into wheelchair seats to detect users’ real-time sitting positions to avoid diseases, such as pressure ulcers and bed sores. Individuals who use wheelchairs are more likely to develop pressure ulcers if they remain in an inappropriate posture for an extended period because the blood supply to specific parts of their skin is cut off owing to increased pressure. Two FSR configurations are tested using seven algorithms of machine learning techniques to discover the optimal fit for a high-efficiency and high-accuracy posture detection system. Additionally, an obstacle detection facility enables one to drive safely in unknown and dynamic environments. An android application is also designed to provide users of wheelchairs with the ease of selecting the mode of operation of the wheelchair and displaying real-time posture and health status to the user or caretaker.

Alterations in Cervical Nerve Root Function during Different Sitting Positions in Adults with and without Forward Head Posture: A Cross-Sectional Study.

The current study aimed to determine whether participants with and without forward head posture (FHP) would respond differently in cervical nerve root function to various sitting positions. We measured peak-to-peak dermatomal somatosensory-evoked potentials (DSSEPs) in 30 participants with FHP and in 30 participants matched for age, sex, and body mass index (BMI) with normal head posture (NHP), defined as having a craniovertebral angle (CVA) >55°. Additional inclusion criteria for recruitment were individuals between the ages of 18 and 28 who were in good health and had no musculoskeletal pain. All 60 participants underwent C6, C7, and C8 DSSEPs evaluation. The measurements were taken in three positions: erect sitting, slouched sitting, and supine. We identified statistically significant differences in the cervical nerve root function in all postures between the NHP and FHP groups (p < 0.001), indicating that the FHP and NHP reacted differently in different positions. No significant differences between groups for the DSSEPs were identified for the supine position (p > 0.05), in contrast to the erect and slouched sitting positions, which showed a significant difference in nerve root function between the NHP and FHP (p < 0.001). The NHP group results were consistent with the prior literature and had the greatest DSSEP peaks when in the upright position. However, the participants in the FHP group demonstrated the largest peak-to-peak amplitude of DSSEPs while in the slouched position as opposed to an erect position. The optimal sitting posture for cervical nerve root function may be dependent upon the underlying CVA of a person, however, further research is needed to corroborate these findings.

Rehabilitation Practitioners’ Perceptions of Optimal Sitting and Standing Posture in Men with Normal Weight and Obesity

The concepts of "optimal posture (OP)" and "harmful posture (HP)" are commonly used, and specific spinal postures can contribute to back pain. However, quantitative descriptions of optimal and harmful standing (StP) and sitting (SP) postures are currently lacking, particularly for different body mass indices (BMIs). Therefore, this study aimed to identify and quantify the OPs and HPs of StP and SP at different BMIs and investigate the attitudes and beliefs of rehabilitation practitioners toward OPs and HPs. Overall, 552 rehabilitation practitioners were recruited to participate in a questionnaire survey to select the optimal position from seven sitting and five standing postures for each BMI healthy volunteer. The segmental relationships of each posture were qualified using the Vicon software. For normal BMI, the physiotherapists chose two SPs (48.19% and 49.64%) and one StP (80.42%) as the OP. One sitting SP (83.7%) and two standing StPs (43.48% and 48.19%) were selected as optimal for obese BMI. All the most commonly selected OPs had an upright lordotic posture, while the postures with slouched spinal curves or forward head postures were almost all selected as HP. Additionally, 96.74% of participants considered education about optimal SP and StP to be "quite" or "very" important. The OP of the StP and SP postures was mostly based on the vertical alignment of gravity lines and sagittal balance. For obese people, the rehabilitation practitioners' observations may be erroneous, and further physical examination is necessary. Rehabilitation practitioners generally believe that postural education is essential in clinical practice.

FACTORS ASSOCIATED WITH SUBJECTIVE COMPLAINTS OF LOW BACK PAIN IN TAILORS AT THE CHILDREN'S PALACE MARKET, JAMBI CITY

Sewing is one of the risky jobs to experience low back pain (LBP) this is due to working with long sitting and non-ergonomic work positions. The Jambi City Children's Palace Market is the central tailor in Jambi City. The results of the observation showed that from 10 tailors, 7 experienced pain in the lower back when sewing. The purpose of the study was to determine the factors associated with complaints of LBP on tailors at the Children's Palace Market. The study used a cross sectional design. The research was conducted at the Istana Children's Market in Jambi City on 10-31 May 2022. The research population was all tailors at the Istana Anak Market. The research sample was 30 tailors at the Children's Palace Market in Jambi City. The research instrument was a questionnaire and RULA. Data collection techniques using interviews and observations of respondents' work attitudes. Data were analyzed using chi square test. As many as 53.3% of respondents have complaints of low back pain, 53.3% of respondents work with high-risk work attitudes, 60.0% of respondents work with risky work durations and 63.3% of respondents have long tenures. The results of the bivariate analysis showed that there was a relationship between work attitude (p=0.000) and tenure (p=0.011) with complaints of low back pain in tailors at the Children's Palace Market, Jambi City. There is no relationship between work duration (p-0.159) and complaints of low back pain in tailors at the Children's Palace Market, Jambi City.

Transformable Wheelchair–Exoskeleton Hybrid Robot for Assisting Human Locomotion

This paper presents a novel wheelchair–exoskeleton hybrid robot that can transform between sitting and walking modes. The lower-limb exoskeleton uses planetary-geared motors to support the hip and knee joints. Meanwhile, the ankle joints are passive. The left and right wheel modules can be retracted to the lower legs of the exoskeleton to prepare for walking or stepping over obstacles. The chair legs are designed to form a stable sitting posture to avoid falling while traveling on smooth surfaces with low energy consumption. Skateboard hub motors are used as the front driving wheels along with the rear caster wheels. The turning radius trajectory as the result of differential driving was observed in several scenarios. For assisting sit-to-stand motion, the desired joint velocities are commanded by the user while the damping of the motors is set. For stand-to-sit motion, the equilibrium of each joint is set to correspond to the standing posture, while stiffness is adjusted on the basis of assistive levels. The joint torques supported by the exoskeleton were recorded during motion, and leg muscle activities were studied via surface electromyography for further improvement.

Short-term effects of side-alternating Whole-Body Vibration on cognitive function of young adults.

Recent research in rodents and humans revealed that Whole-Body Vibration (WBV) is beneficial for cognitive functions. However, the optimal WBV conditions are not established: contrary to vertical WBV, side-alternating WBV was not investigated before. The present study investigated the short-term effects of side-alternating WBV in standing and sitting posture on specific cognitive function of young adults. We used a balanced cross-over design. Sixty healthy young adults (mean age 21.7 ± 2.0 years, 72% female) participated. They were exposed to three bouts of two-minute side-alternating WBV (frequency 27 Hz) and three control conditions in two different sessions. In one session a sitting posture was used and in the other session a standing (semi-squat) posture. After each condition selective attention and inhibition was measured with the incongruent condition of the Stroop Color-Word Interference Test. WBV significantly (p = 0.026) improved selective attention and inhibition in the sitting posture, but not in the standing posture. The sitting posture was perceived as more comfortable, joyous and less exhaustive as compared to the standing posture. This study demonstrated that side-alternating WBV in sitting posture improves selective attention and inhibition in healthy young adults. This indicates that posture moderates the cognitive effect of WBV, although the effects are still small. Future studies should focus on the working mechanisms and further optimization of settings, especially in individuals who are unable to perform active exercise.

The prevalence and risk factors of work related musculoskeletal disorders among electronics manufacturing workers: a cross-sectional analytical study in China

ObjectivesTo describe the prevalence of self-reported musculoskeletal disorders among workers in the electronics manufacturing industry and to investigate the relations between work-related musculoskeletal disorders (WMSDs) and work-related variables.MethodsAn interview-based questionnaire survey was carried out in thirty electronics manufacturing factories in China in 2018. The prevalence of WMSDs was estimated using the modified Nordic Musculoskeletal Questionnaire (NMQ). A multivariate logistic regression model was applied to evaluate the effects of risk factors on WMSDs on multiple body parts.ResultsThe 12-month prevalence of WMSDs among participants was 40.6%, and the common body sites affected were the neck (26.8%), shoulder (22.8%), upper back (14.9%), and lower back (14.8%). The results of logistic regression showed that female adults, > 5 job tenure and work-related factors (including awkward posture, lifting or carrying weights, excessive repetition, prolonged sitting, monotonous work and working under conditions of cold or temperature variations) led to a higher risk of WMSDs on most body parts. Upper back, wrist/hand and elbow pain levels were significantly higher for workers with vibration. However, more frequently, physical exercise was a protective factor against WMSDs on most body parts except the upper back, leg and knee.ConclusionsThe study indicates a high prevalence of musculoskeletal pain among the electronics manufacturing industry in China. Different personal and work factors are related to the occurrence of WMSD on different body parts. Preventive measures should be implemented based on the characteristics of WMSD in the electronic manufacturing industry. Furthermore, the training and intervention guidance of ergonomic hazards in the workplace need to be strengthened by understanding the impact of bad posture, avoiding long-term sitting posture and increasing physical activities.

Examination of the correlation between the knee extension angles in the sitting and supine positions measured using ImageJ software: a prospective cross-sectional study.

[Purpose] We aimed to examine the correlation between the knee extension angles in the sitting and supine positions measured using ImageJ software. [Participants and Methods] A total of 50 legs in 25 healthy participants (17 males and 8 females) were included in our study. The knee extension angle was measured in the sitting and supine positions with the participants actively and maximally extending their knee joint on one side. The participants were photographed from the side with their knees centered in the image. Thereafter, the photographs were imported into the ImageJ image processing software to calculate the knee extension angles. [Results] The mean values of the knee extension angles in the sitting and supine positions were 131.5 ± 11.2° and 132.1 ± 12.2°, respectively, with a correlation coefficient of 0.85. No systematic errors were observed, and the minimal detectable change was 12.9°. [Conclusion] The knee extension angle in the sitting position showed a strong correlation with that in the supine position, with no systematic errors observed. Therefore, measurement of the knee extension angle in the sitting position can be an alternative to its measurement in the supine position.

The effect of body position on the results of central and paracentral rebound tonometry

This study analyzes the fluctuations of intraocular pressure (IOP) and clarifies the error of paracentral rebound tonometry associated with change in body position. The study included 45 healthy volunteers aged 25.4±2.1 years. First we performed rebound tonometry in the sitting position in the center of the cornea and 3-4 mm from the temporal and nasal sides (Icare-c, Icare-n, Icare-t, respectively) and bidirectional applanation tonometry (IOPcc - corneal compensated, IOPg - Goldmann tonometry). Then we measured Icare-c, Icare-n, Icare-t in the supine position, and after 5 minutes repeated Icare-c in the supine position. After this, we measured Icare-c, IOPcc and IOPg in the sitting position. Initial IOPcc and IOPg were 4.6±2.8 and 14.8±2.8 mm Hg. Initial Icare-c, Icare-t, and Icare-n measurements amounted to 15.0±1.9, 15.7±1.5 and 16.3±1.3 mm Hg; in the supine position the measurements were 16.4±2.1, 17.2±1.7 and 17.1±1.9 mm Hg. Paracentral measurements differed from Icare-c in both sitting and supine positions; only between Icare-t and Icare-n measured in the supine position there were no significant differences. The results of Icare-c, Icare-t, and Icare-n in body position change were comparable. Icare-c measured after 5 minutes in the supine position increased up to 16.6±2.4 mm Hg. Final IOPcc and IOPg did not differ from the initial measurements. Final Icare-c was lower than the initial result by 0.8±0.2 mm Hg, and lower than both supine Icare-c measurements by 2.1±0.2 and 2.6±0.2 mm Hg. Paracentral rebound tonometry findings exceed those of rebound tonometry in central cornea, but in body position change the alteration of measurements in the same points on the cornea are comparable. In the supine position IOP increases on average by 1.0-1.5 mm Hg compared to the sitting position.