A biomechanical analysis of active vs static office chair designs

Effectiveness of a dynamic seat cushion on recovery and recurrence of neck and low back pain in office workers: a secondary analysis of a randomized controlled trial

BACKGROUND

Neck and low back pain are prevalent issues among office workers due to prolonged sitting, necessitating effective interventions. Dynamic seat cushion, designed to promote postural shifts, have emerged as promising solutions to address this concern. This study aims to evaluate the effectiveness of a dynamic seat cushion on recovery and recurrence of neck and/or low back pain in office workers.

METHODS

This study used 6-month follow-up data of a randomized controlled trial, involving 66 office workers who reported neck and/or low back pain during the trial. At baseline, participants were cluster-randomized into an intervention group, which received a dynamic seat cushion designed to encourage postural shifts, or a control group, which received a placebo seat pad. Health outcomes included recovery duration and recurrence of pain. Analyses utilized log rank test and Cox proportional hazard models.

RESULTS

The recovery rate from neck and/or low back pain was 100% for the intervention group, and 86% for the control group. The median recovery duration of participants who reported pain during the 6-month period was 1 month in the intervention group and 3 months in the control group. The intervention group had a higher probability of recovery compared to the control group (HRadj 4.35, 95% CI 1.87-10.11; p < 0.01). The recurrence rate of neck and low back pain was 27% in the intervention group, which was 75% in the control group. The Hazard Ratio, after adjustment, for the intervention group compared to the control group was 0.50 (95% CI = 0.11-2.12).

CONCLUSIONS

A dynamic seat cushion that encourages postural shifts shortened recovery duration of neck and low back pain among office workers. Due to small numbers, a potentially relevant reduction in the recurrence of neck and low back pain could not be statistically confirmed. A power analysis was not conducted for this secondary analysis, and future studies should be designed with adequate sample sizes to explore the recurrence of pain with greater statistical power.

TRIAL REGISTRATION

This trial is retrospectively registered under the Thai Clinical Trials Registry: TCTR20230623002 (23/06/2023).

Evaluation of the effect of corrective exercise intervention on musculoskeletal disorders, fatigue and working memory of office workers

Objectives: The present study aimed to investigate the effect of corrective exercise intervention (corrective exercise reminding and training software) on musculoskeletal disorders (MSDs), fatigue, posture and working memory among office workers. Methods: A total of 66 office workers participated in the present study. Data collection was carried out using questionnaires (including the Nordic musculoskeletal questionnaire, multidimensional fatigue inventory and Borg rating scale), direct observations of work postures using rapid upper limb assessment (RULA) and rapid office strain assessment, and the n-back test. Results: There was a significant difference between the two groups (intervention and control) in terms of the severity of musculoskeletal discomfort after the intervention. There was a significant decrease in the mean score of trunk posture and the total RULA score in the intervention group after the intervention. The severity of perceived discomfort in all areas except the knee declined during the intervention. There was also a significant difference in physical and mental fatigue scores before and after the intervention. There was a significant difference in the accuracy score of office workers after the intervention compared to before the intervention. Conclusions: Overall, the results confirm the effectiveness of this low-cost, simple and easy-to-use ergonomic intervention.

A systematic review of research on sitting and working furniture ergonomic from 2012 to 2022: Analysis of assessment approaches

This study analyses which aspects of sitting and working furniture ergonomics that may be influenced and how they are assessed. To gather information on the types and assessment techniques connected with influencing furniture ergonomics, a systematic review of the literature was conducted. The papers in the systematic review were published between 2012 and 2022. The articles applied the Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines to limit the 41 papers that were eventually included (N = 41) to those containing keywords like ergonomics, human factors, comfort, working furniture, Chair, assessment and evaluation. The research objective of this systematic review is to provide a comprehensive overview of sitting and working furniture and the main findings, obtaining common assessment techniques for this type of furniture and their suitability. According to the relevant studies, the publications were categorized by summarizing factors like region, gender, research methods, ergonomic assessment techniques and methods used, correlation between assessment techniques and methods, etc. Summaries of the data extracted from the included papers are provided and the applicability of some approaches are assessed. Only a small number of authors have evaluated the ergonomics of furniture used in homes. One of the research gaps is the paucity of research on gender segregation, secular trends, and cultural contexts. These studies heavily rely on quantitative research techniques, and the articles may lack credibility due to the homogeneity of the evaluation techniques. Finally, the authors offer some suggestions for the appropriate ergonomic analysis of furniture.

Active workstations: A literature review on workplace sitting

The purpose of this paper is to further understand current literature on prolonged sitting, sitting posture and active sitting solutions. This paper is divided into three sections: The first section (Part I) is a comprehensive overview of the literature on how a static prolonged seated posture can affect: spinal health, trunk posture, contact pressure/discomfort development and vascular issues. The second section (Part II) reviews and qualitatively compares the four working postures recognized in ANSI/HFES 100-2007: reclined sitting, upright sitting, declined sitting and standing. The final section (Part III) is a summary of research on active chairs that revolves around the two types of movement patterns: 1- sustaining continual movement over a range of postures, occasionally reaching neutral lordosis, and 2- maintaining high frequency and duration of daily light contractile activity in the legs (or lower limbs).

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.

The biomechanical benefits of active sitting

This cross-sectional study examined the biomechanical effects of two active chairs (AC1: had the feature to pedal and slide forward on the seat pan; AC2: a multiaxial motion seat pan) compared to a traditional office chair and standing workstation. Twenty-four healthy participants worked at each of the workstations for 60-min. The following equipment was used: Motion Capture, Electromyography, Ratings of Perceived Discomfort Questionnaire, and Exit Survey. The active protocol had positive effects on the body, including increased neuromuscular activity in the gastrocnemius, increased overall movement, and a more open trunk-thigh angle. Greater discomfort in the buttocks due to the lack of seat pan contour was reported for the AC1 which identified a need for a design modification. While standing, participants' shoulders were less flexed than when sitting in any of the three seats, however, greater discomfort was reported in the lower legs after 1 h of computer work. Practitioner summary: A comparison of four different workstations was conducted to further understand the use of active workstations. Active sitting was found to have positive effects on the body, such as allowing sitters to increase movement while sitting without the high activation of muscular activity. Standing can also provide a positive break from sitting.

Does active sitting provide more physiological changes than traditional sitting and standing workstations?

This cross-sectional study examined the physiological effects of two active chairs (AC1: had the feature to pedal and slide forward; AC2: was a multiaxial chair) compared to a traditional office chair and standing workstation. Twenty-four healthy participants computed at each of the workstations for 60 min. The active protocol was to alternate between a pedalling/side-to-side motion and sliding forward/front-to-back motion to the sound of a metronome operating at 40 bpm. The participants' physiological effects were recorded using near-infrared spectroscopy (NIRS); electrodermal activity (EDA) and a heart rate (HR) monitor for each collection period. Statistical analysis was conducted using a repeated measures analysis of variance for within-task and between-workstation comparisons. A Tukey's post hoc analysis was calculated for significant findings. Both active chairs significantly increased oxygenated blood in the gastrocnemius and participants' heart rate and EDA (stress) levels were affected slightly by task and time. However, participants felt more "productive" sitting in the control chair than in either of the active chairs.