Seat Height Research Articles

Survey on Low Back Pain among Cyclists: Prevalence, Risk Factors and Knowledge of Injury Prevention Strategies

The study aimed to determine prevalence of low back pain (LBP), risk factors, and knowledge of injury prevention strategies in recreational cyclists. Materials and methods. This cross-sectional quantitative study included 141 adult recreational cyclists aged 18 to 70. LBP prevalence was determined using a standard Nordic questionnaire. In addition, a validated self-developed questionnaire was used to assess knowledge level, with a high score representing the highest level of knowledge. Frequencies and percentages were used to report the descriptive variables, whereas the Chi-square test was used to determine the association between risk factors and LBP. Results. The study identified that 55.3% of cyclists had a lifetime prevalence of LBP, and 35.5% reported LBP in the past 12 months. However, no significant association (p>0.05) was found between the risk factor and the LBP. Despite this, a low level of knowledge of injury prevention strategies for recreational cyclists was found. Conclusions. This survey found that recreational cyclists have a low level of understanding about crucial bicycle characteristics such as seat height, saddle tilt, and handlebar position to maintain optimal body biomechanics. Recreational cyclists should be educated on the need for appropriate bicycle modifications and ergonomics, effective warm-up, stretching, and cool-down techniques, and some critical injury prevention strategies, especially in the low back.

Differences in the Timed Up and Go Test under different measurement conditions in young healthy adults.

[Purpose] The purpose of this study was to verify whether Timed Up and Go (TUG) test measurements differed according to the seat height of the chair, presence or absence of armrests, and measurement location in young healthy adults, and to clarify the flexibility of the TUG settings. [Participants and Methods] Fifty-nine young healthy males and females participated in this study. The TUG test was performed under several conditions. Eight measurements were obtained at both the usual walking speed and the individual's fastest walking speed. [Results] There were no significant differences in TUG test measurements according to variation in seat height, different measurement locations, with and without the use of armrests, or at the usual walking speed or the fastest walking speed. [Conclusion] In young healthy adults, TUG test measurements were unaffected by differences in chair height, use of armrests, or the location of the measurement. If TUG measurements are found to differ according to these variables, it is necessary to consider the influence of the individual's ability rather than the measurement method.

Dimensional Solution of Wooden Chairs for the Adult Bariatric Population of Slovakia: Observational Study

Chairs are furniture that are intended for direct contact with people, they are heavily loaded by forces, and they must meet a number of criteria, such as ergonomics, safety, economic sustainability, feasibility, and aesthetic requirements. This study aimed to define the dimensional solution of wooden chairs for the adult bariatric subpopulation of Slovakia. Long-term observations of the changes in the anthropometric dimensions of the population (secular trend) allowed the determination of the body height of 95% of the adult male population. Based on the analysis of the bariatric population of Slovakia, regardless of gender, the values of weight, waist and hip circumference, and seat width were defined in the years 2020 to 2022. The increased population’s average body mass makes the researched topic highly relevant and necessary. Based on the obtained data, new dimensions of wooden chairs for bariatric respondents were designed: seat height 49 cm, seat width 67 cm, and seat depth 47 cm. Adjusting the dimensions of wooden chairs makes it possible to ensure comfortable sitting and standing for bariatric respondents and prevents many health problems. For furniture manufacturers, the introduction of the production of wooden furniture for bariatric respondents can be a competitive market advantage.

Design and fabrication of electric three-wheeled scooter for disabled persons

This article focuses on offering a possible design and manufacturing in the shape of a user-friendly-three-wheeled scooter, which lets in bodily challenged or persons with partial incapacity to move and do their activities without anyone’s assistance. The problems were observed through a survey conducted to understand their needs, particularly dimensions. Major problems such as seat height and floor clearance were taken into consideration to increase the standards and its selection. From the survey, it was found that our electric three-wheeled scooter should have high range and be comfortable during travel. It should also be affordable. Then, the accurate design of the proposed model was finalized using Solidworks. We used a hub motor, battery, and control system that can give a range of 45 km/h and have load-carrying capacity of 100 kg. The designed scooter is ergonomically suited for disabled persons in comparison to the conventional scooters used by them.

KNOWLEDGE REGARDING ERGONOMICS TO PREVENT HEALTH HAZARDS OF EXTENDED COMPUTERS USAGE AMONG ADMINISTRATIVE STAFF

Introduction: The science of creating a job to fit the worker is known as ergonomics. Ineffectiveness and suffering at work stem results from disregarding ergonomic principles. Poor seating, a lack of frequent short pauses while working, and poor viewing distance all contribute to symptoms like pain, numbness, tingling, etc. in various body parts like the wrists, shoulders, back, and legs as well as eye strains. Numerous health risks can be avoided with correct workplace organisation, seat height, working posture, armrest and backrest use, wrist and elbow alignment that is straight, and keyboard positioning.
 Methodology: A self-structured knowledge questionnaire was used to collect data from 150 study participants who were chosen through the purposive sample method. To collect information about personal profile variables, a self-structured knowledge questionnaire is used. The study's results showed that the majority of participants, 60.7%, had average knowledge, 20.7% had poor knowledge, and 18.7% had good knowledge regarding ergonomics to prevent the health risks associated with prolonged computer use. Except for the length of computer stay, which was found to be statistically significant at the 0.05 level of significance, the majority of the demographic variables were not significantly associated with the level of administrative staff knowledge regarding ergonomic to prevent health hazards of extended computer usage.
 Conclusion: Study concluded that administrative staff have average knowledge (60.7%) regarding ergonomic to prevent health hazard of extended computers usage and only 18.7 % of study participants have good knowledge regarding ergonomic to prevent health hazard of extended computers usage.

고령친화 운동의자 개발 사례연구

Purpose: The purpose of this study is to develop an exercise chair that reflects the body size of older adults with embedding exercise functions for the arm and legs.BR Method: The development of the exercise chair was completed through chair design, plan, production and modification based on the selection of the requirements for an age-friendly exercise chair with the execution of the research of related documents and market and the actual measurement of the older adults’ body size (158 old people, from 65 to 94 years old) and interviews (10 old people who attend silver welfare center, 10 senior sports instructors, and 14 employees of silver welfare center) from February 2019 to March 2020.BR Results: The developed exercise chair took into account the body dimensions of older adults’ (seat height 380 mm, back height 900 mm) and equipped the exercise functions of psoas muscles, hip adductor muscles, biceps, and rotator cuff muscles. The improvement of the exercise chair appeared as the amendment of design for the revelation of resistibility on function for arm movement, adjustment of operation allowance during input and output of leg movement tool and addition of finishing touches to solve noise problems on the operation unit of arm movement.BR Conclusion: In this way, a change of perception and active industry-university cooperation are required so that age-friendly development studies such as this exercise chair developed by considering the exercise conditions of the elderly welfare facility and reflecting the body size of the elderly can be attempted in the field of sports for the elderly.

The Applicability of the Hertzian Formulas to Point Contacts of Spheres and Spherical Caps

Hertzian formulas are commonly used for the evaluation of deformation and pressure distribution of non-conformal and slightly conformal mechanical pairs to estimate component stiffness and durability. For the sake of simplicity, their use is extended even to those cases in which Hertz’s hypotheses do not hold. This paper summarizes Hertz’s theory and compares the results obtained with theoretical and finite element analysis of the point contact of non-conformal and conformal pairs made of spheres, caps, and spherical seats. This study was motivated by the non-Hertzian behavior of a tilting pad bearing ball-and-socket pivot conforming contact observed by the authors in previous experiments. In particular, the displacement and force relation were investigated by varying the geometrical parameters, the materials, the boundary conditions, and the friction coefficient. In the case of non-conformal contact, the parameter variations had negligible effect in agreement with Hertz’s theory while for conformal contact, the cap and seat height and width and the relative clearance were the most influential parameters on the non-Hertzian behavior. These novel results indicate that in conformal pairs, such as for tilting pad bearing ball-and-socket pivots, whenever Hertz’s hypotheses are not satisfied and the assessment of contact stiffness is crucial, Hertzian formulas should not be applied as done in common practice, instead more accurate numerical or experimental evaluation should be made.

Ergonomic evaluation of school furniture in Slovenia: From primary school to university.

BACKGROUND:Adequate school furniture is important to prevent musculoskeletal discomfort among students.OBJECTIVE:The aim of the study was to assess the suitability of school furniture compared to body dimensions of students.METHODS:A cross-sectional study included a total of 442 students from primary school, secondary school, and university. Nine body dimensions along with five furniture dimensions were measured and equations for mismatch criteria were applied.RESULTS:In primary school, differences in body dimensions were more evident among students of different age, while in secondary school and university, differences between male and female students became more apparent. The mismatch for desk height ranged from 100.0% at primary school to 48.0% at university. Similarly, the seat height mismatch was the most evident in primary school (89.7% –94.6%), lower at university (52.0%) and the lowest in secondary school (18.0%). The seat depth mismatch was present among all groups, ranging from 23.1% to 40.4%, and was in general more pronounced in males. Seat to desk clearance mismatch was the most evident among secondary school students. In primary school, seat and desk height were generally too high for most of students.CONCLUSIONS:Specific differences in body dimensions among groups of students of different age and gender were observed and a high student-furniture mismatch was identified in all educational institutions. Implementation of adjustable school furniture, covering at least two size marks, is needed to provide ergonomic and healthy learning conditions and to further enhance the comfort and well-being of students in the classroom.

Ergonomics Simulation and Analysis of Specially Designed Chair

Chair comes in different sizes and shapes depending on the functions as well as the users involved. However, the designers seldom consider the ergonomics aspect in chair design. This research has been conducted as a case study to compare and select the best design parameters within two chairs known as Chair A and B using human modelling software called AnyBody. Different parameter was manipulated in the simulation which is backrest angles for Chair A and seat heights for Chair B. A total of ten chairs with different parameters (five from Chair A and five from Chair B) were conducted in the simulation. Results were generated through inverse dynamics analysis in the form of muscle activities envelopes and reaction force on vertebrae L4 to L5. The result shows that 80° backrest was the best ergonomics design for Chair A while 0.30 m seat height was the best ergonomics design for Chair B. The simulation conducted is important as an early ergonomics intervention before the real chair fabrication is conducted.

Prediction of Propulsion Kinematics and Performance in Wheelchair Rugby.

Prediction of propulsion kinematics and performance in wheelchair sports has the potential to improve capabilities of individual wheelchair prescription while minimizing testing requirements. While propulsion predictions have been developed for daily propulsion, these have not been extended for maximal effort in wheelchair sports. A two step-approach to predicting the effects of changing set-up in wheelchair rugby was developed, consisting of: (One) predicting propulsion kinematics during a 5 m sprint by adapting an existing linkage model; and (Two) applying partial least-squares regression to wheelchair set-up, propulsion kinematics, and performance. Eight elite wheelchair rugby players completed 5 m sprints in nine wheelchair set-ups while varying seat height, seat depth, seat angle, and tire pressure. Propulsion kinematics (contact and release angles) and performance (sprint time) were measured during each sprint and used for training and assessment for both models. Results were assessed through comparison of predicted and experimental propulsion kinematics (degree differences) for Step One and performance times (seconds differences) for Step Two. Kinematic measures, in particular contact angles, were identified with mean prediction errors less than 5 degrees for 43 of 48 predictions. Performance predictions were found to reflect on-court trends for some players, while others showed weaker prediction accuracy. More detailed modeling approaches that can account for individual athlete activity limitations would likely result in improved accuracy in propulsion and performance predictions across a range of wheelchair sports. Although this would come at an increased cost, developments would provide opportunities for more suitable set-ups earlier in an athlete's career, increasing performance and reducing injury risk.

Characteristics of human movement and injury in a side collision between the front of a small car and a bicycle

ObjectiveOur research groups have studied the movement and injury characteristics of the human body in a side collision between the front of a small car and a pedestrian. This study discusses the movement and injury characteristics of the human body in a side collision between the front of a small car and bicycle. MethodsA total of 31 cases of traffic accidents caused by small car collisions when riding a bicycle across a road were collected. Through on-site inspection and trace inspection of the accident vehicles and bicycles, the speed of the car during the collision was calculated, the collision relationship between the small car and bicycle was determined, and the injury site and degree were determined through autopsy. The car speed was divided into two groups: <60 km/h and >60 km/h. Injuries of the skull, cervical spine, ribs, pelvis, femur and tibiofibular were analysed, and the correlations with the height of the bicycle controller, the height of the bicycle seat, the height of the car hood and the length of hood were discussed. PC-Crash was used for simulation analysis to further clarify the injury process. ResultsThe ratio of the height of the bicycle seat to the height of the hood plus the length of the hood in the windshield-damaged group was larger than that in the undamaged windshield group (P < 0.05). No cervical fracture was found when V < 60 km/h, and 52.94% of cases had cervical fracture when V > 60 km/h. The ratio of the height of the bicycle seat to the height of the hood in the pelvic fracture group was smaller than that in the nonpelvic fracture group (P < 0.05). The incidence of tibiofibular fracture was less than 65%. ConclusionsWhen a side impact between a car front and a bicycle occurs, the resulting human injury is related not only to the speed but also to the height of the bicycle seat and the height and length of the hood of the car. The incidence of tibiofibular fractures was significantly lower than that of small car front-pedestrian side impacts.

The impact of seat height on 1-min sit-to-stand test performance in COPD: a randomised crossover trial.

Study questionIs there a difference in the number of repetitions in the 1-minute sit-to-stand (1MSTS) test using an individually adapted seat height to 90° knee flexion (1MSTSIND), compared with the commonly used standard chair seat height of 46 cm (1MSTSSTD), in people with COPD?MethodsWe conducted a single-centre, single-blinded, randomised crossover trial in people with COPD between August 2020 and March 2021 at a specialised rehabilitation clinic in Switzerland. After a learning 1MSTS test, all participants performed two 1MSTS tests in random order on consecutive days. Participants were blinded, as they did not receive detailed information on the testing protocols.Results49 individuals with COPD (47% female) participated. In a regression model adjusted for sequence period and subject, 1MSTS test performance was lower on 1MSTSIND compared to 1MSTSSTD (−0.78 repetitions, 95% CI −1.47 to −0.11). In a second regression model additionally including the knee angle and an interaction term (1MSTSIND×knee angle), the interaction term was significant: 0.18 (95% CI 0.05 to 0.30). The limits of agreement were between −5.5 and 4 repetitions.ConclusionAlthough we observed a statistically significant difference between 1MSTSIND and 1MSTSSTD on a population level, the difference is negligible. Further studies may be needed to determine whether individual adaptation of seat height is needed for very tall or short people to ensure a valid assessment of 1MSTS test performance in COPD.

A Machine Learning Model for Predicting Sit-to-Stand Trajectories of People with and without Stroke: Towards Adaptive Robotic Assistance.

Sit-to-stand and stand-to-sit transfers are fundamental daily motions that enable all other types of ambulation and gait. However, the ability to perform these motions can be severely impaired by different factors, such as the occurrence of a stroke, limiting the ability to engage in other daily activities. This study presents the recording and analysis of a comprehensive database of full body biomechanics and force data captured during sit-to-stand-to-sit movements in subjects who have and have not experienced stroke. These data were then used in conjunction with simple machine learning algorithms to predict vertical motion trajectories that could be further employed for the control of an assistive robot. A total of 30 people (including 6 with stroke) each performed 20 sit-to-stand-to-sit actions at two different seat heights, from which average trajectories were created. Weighted k-nearest neighbours and linear regression models were then used on two different sets of key participant parameters (height and weight, and BMI and age), to produce a predicted trajectory. Resulting trajectories matched the true ones for non-stroke subjects with an average score of using k = 3 and 100% seat height when using height and weight parameters. Even among a small sample of stroke patients, balance and motion trends were noticed along with a large within-class variation, showing that larger scale trials need to be run to obtain significant results. The full dataset of sit-to-stand-to-sit actions for each user is made publicly available for further research.

Anthropometric Seat Design for Bus Drivers in Southwestern Nigeria

Most buses used in Nigeria are imported; thus, the anthropometric dimensions of the citizens of the country of manufacture were used for the seat design. Poorly designed seats due to a mismatch in anthropometric measurements may lead to musculoskeletal disorders. Hence, there is a need to design an appropriate seat for particular bus drivers. This study aimed to obtain anthropometric dimensions of Nigerian bus drivers and design an appropriate driver’s seat based on the collected dimensions. Relevant anthropometric variables necessary for the driver’s seat design were obtained from 150 randomly selected male bus drivers from seven towns in Ogun, Oyo and Lagos states. Seat dimensions of 50 urban buses in heavy and medium automobile categories were considered. The means, standard deviations and 5th, 50th and 95th percentiles were calculated. The existing seat dimensions were compared with the required anthropometric measurements of the drivers for the seat design. It was found that the current seat measurements differed from the suggested seat dimensions. The study highlighted that in designing and producing bus seats for Nigerian bus drivers, their anthropometric data should be considered. The study recommended that the dimensions of the driver’s seat should be 46.45-50.45 cm (seat height); 39-48.26 cm (seat depth); 46.83 cm (seat front width); 53 cm (backrest height); 49-58.26 (backrest depth); and 90° to 130° (seat backrest angle).

Intelligent Structure Design of Learning Seats in University Smart Classroom under the Background of Intelligent Education.

Under the background of intelligent education, the study chairs of intelligent classrooms in colleges and universities should reflect humanistic care and design and guide students to establish a healthy learning style. To realize the intelligent classroom learning, the intelligent seat can be applied to different sitting positions or different heights and weights. This paper designs a control system based on MC9S08DZ60 and realizes the communication between the control system and the mobile app by combining the Bluetooth module based on CSR8670. At the same time, this paper proposes an intelligent design that can adjust the seat height by voice. LD3320 speech recognition module is used for voice control, and a push rod motor with a rising speed of 7 mm/s is used to complete the lifting to meet the requirements of different sitting positions and different heights and weights. Then, the folding design of the intelligent seat for classroom learning is carried out. Infrared detectors are used at the armrests on both sides of the seat. When people have a tendency to sit down, they will speed up deployment. When a person leaves the seat, the seat will automatically retract. Finally, the objective evaluation method of pressure distribution test experiment is compared with the subjective scale evaluation of students, which verifies the effectiveness of the shape design of the chair in keeping students' healthy sitting posture for a long time.

Assessing the ergonomic status of commonly used chairs in Iran's universities based on combinational equations and anthropometric indices.

Inappropriate design of chairs and disproportion with students' body dimensions can influence their physical and mental health as well as their educational efficiency and concentration. The aim of this study was to examine the ergonomic status of commonly used chairs in Iran's universities using combinational equations and anthropometric indices. Participants in this cross-sectional study were 166 students in Iran. Eleven anthropometric parameters of the students and nine dimensions in seven types of commonly used chairs in Iran's universities were measured. Combinational equations were used to determine the fitness of the chairs. There was a major mismatch between most students' anthropometric measurements and the dimensions of the chairs. Backrest height and seat height were the best and the worst features, respectively, according to ergonomic recommendations for chairs. The recommended measurements of seat height, seat depth, seat width, desk height, desk width, desk length, backrest width, backrest height, and desk distance were 332, 420, 436, 245, 95, 511, 426, 550, and 281 mm, respectively. None of the commonly used chairs in Iran's universities were found to be a good fit to the students' anthropometric dimensions. Therefore, in order to prevent inappropriate body postures, chair designs have to reviewed, and made to fit with Iranian students' anthropometric data. The recommended measurements obtained in this study can be used to design a suitable ergonomic chair to match with a high percentage of Iranian students.

The role of at home workstation ergonomicsand gender on musculoskeletal pain.

The recent mandate for university faculty and staff to work-from-home (WFH) during the COVID-19 pandemic has forced employees to work with sub-optimal ergonomic workstations that may change their musculoskeletal discomfort and pain. As women report more work-related musculoskeletal discomfort (WMSD), this effect may be exacerbated in women. The purpose of this study was to describe university employee at-home office workstations, and explore if at-home workstation design mediates the effect of gender on musculoskeletal pain. University employees completed a survey that focused on the WFH environment, at home workstation design and musculoskeletal pain. Descriptive statistics and regression analysis were used to analyze the responses. 61% of respondents reported an increase in musculoskeletal pain, with the neck, shoulders and lower back being reported most frequently. Women reported significantly greater musculoskeletal pain, but this relationship was significantly mediated by poor ergonomic design of the home workstation. Improper seat-height and monitor distance were statistically associated with total-body WMSD. WFH has worsened employee musculoskeletal health and the ergonomic gap between women and men in the workspace has persisted in the WFH environment, with seat height and monitor distance being identified as significant predictors of discomfort/pain.

Approach for ergonomic assessment of self-propelled combine harvester seats based on anthropometric body dimensions

Objectives. The seat dimensions of self-propelled combine harvesters are designed without consideration of body dimensions of the user population and vary with make and models of combines. Methods. This research proposes a method to determine the percentage of seat match, upper mismatch and lower mismatch using the anthropometric body dimensions of Indian harvester operators. The seat dimensions of five popular combine harvester makes were measured and compared to the body dimensions of the operators. Results. The selected seats had 100, 44–70, 81–96, 98–100, 63–83, 59–94 and 55–97% mismatch for seat height, seat length, seat pan breadth, seat backrest height, upper backrest breadth, lower backrest breadth and steering wheel clearance, respectively. These data were used to recommend seat dimensions for combine harvesters. Seat height, seat length, seat pan breadth, seat backrest height, upper backrest breadth, lower backrest breadth and steering wheel clearance are recommended as 399, 362, 456, 400, 243, 386 and 190 mm, respectively. Conclusions. The recommended seat dimensions matched the user population anthropometric dimensions 94–100%. This approach will help to assess seat dimensions based on anthropometric data for a comfortable posture to prevent health risks such as musculoskeletal disorders (MSDs) among operators.

Customer-oriented product design using an integrated neutrosophic AHP & DEMATEL & QFD methodology

With the increasing product variety, companies aim to become better than their competitors by providing a superior product developed with a customer-oriented product design approach and a quality strategy. In order to achieve this, companies should well understand customer expectations and quickly be able to convert these expectations to technical characteristics. Since the expectations consist of mostly subjective judgments, this evaluation process contains vagueness and impreciseness. A triplet represents the uncertainty in subjective judgments: the degrees of belongingness or Truthiness (T), non-belongingness or Falsity (F), and indeterminacy (I). For this reason, in this paper, a neutrosophic Quality Function Deployment (QFD) methodology based on neutrosophic AHP and neutrosophic DEMATEL is developed and applied to the design of a car seat. In this methodology, the weighting of customer requirements is performed by neutrosophic AHP. The relationships among the technical characteristics are determined by neutrosophic DEMATEL for the customer-oriented product design, considering both impreciseness in the data and indeterminacy of the decision-makers. In other words, the contribution of this paper is that the proposed methodology provides better integration of the voice of customers into technical characteristics through a practical fuzzy multi-criteria decision analysis. Based on the results, it is revealed that seat height is the most important technical characteristic, followed by vertical travel range and horizontal travel range. Moreover, validity and verification of the proposed methodology have been tested with other methods presented in the literature. Sensitivity analyses have been carried out to show the flexibility of the given decisions under different cases. Lastly, possible implications on theoretical and managerial aspects have been discussed.

Effect of different seat heights on lumbar spine flexion during stand-to-sit motion.

[Purpose] This study aimed to investigate the movement of the thorax, lumbar spine, and pelvis when healthy participants sit on a chair, and to identify the kinematic characteristics due to changes in the height of the seat. [Participants and Methods] Twenty healthy participants (14 males, 6 females; mean age, 29 ± 5 years) were recruited for this study. They performed stand-to-sit motion using one seat with a height of 100% that of the lower leg length (standard) and another with a height of 60% that of the lower leg length (lower). A three-dimensional motion analysis system and four force plates were used to analyze each joint angle. [Results] The mean lumbar spine flexion angle was significantly increased in the lower versus the standard seat. As a kinematic characteristic, the pelvis tilted posteriorly while the thorax tilted anteriorly, which increased the lumbar spine flexion angle. The pelvis was tilted posteriorly when the hip joint flexed about 60° regardless of the seat height. [Conclusion] The lumbar spine flexion angle increased in the lower seat stand-to-sit motion, which suggested an increase in the load on the lumbar spine. The lumbar spine flexion angle was influenced by the characteristic movements of the thorax and pelvis.