Product and building-related features are sometimes perceived differently across studies because they are experienced in different environmental contexts. The proposed Max-Min Kano methodology evaluates office design features under two contrasting contexts: a minimal environment with few positively appraised attributes and a maximal environment with many. Office-relevant attributes were identified through participatory elicitation and then evaluated using a Kano questionnaire (N = 32). Perceptual robustness was defined as retention of a Kano classification across the two contexts, while participant-level bootstrapping assessed sampling stability. View-related variables, window size, biophilic views, fewer façade obstructions, and proximity to windows were stable across contexts. They were Attractive, meaning they added satisfaction even when not strictly expected. In contrast, privacy provided by partitions emerged as a Must-be quality, while the presence of windows and ceiling height showed a One-dimensional relationship with satisfaction in both contexts. Other attributes, such as the seated-desk view, density, partition height, focal points, color, and materiality, were more sensitive to the baseline context. Adaptation-Level Theory, Stress Recovery theory, Attention Restoration theory, and Prospect-Refuge theory help explain these results. Overall, the Max-Min Kano approach helps identify features that remain perceptually robust across contexts, making it useful for prioritizing design features in real-world settings. The study shows that Kano categories are context-expressive rather than being intrinsic properties of features. For this reason, baseline context should be reported when evaluating user preferences across different spatial conditions.
Firefighting involves physically demanding tasks performed under high heat and time pressure. While previous research reports the physical load involved, the extent to which physical fatigue impedes firefighting performance, especially in shipboard environments remains underexplored. Using a laboratory-based shipboard firefighting simulation, this study investigated how physical fatigue and heat influences time-to-completion (TTC), perceived workload, and muscular strength. Thirty participants completed the simulation in Fresh, Fatigue, and Fatigue + Heat conditions, followed by physical performance testing. Compared to Fresh, simulation TTC increased by 7.2% and 8.5% under Fatigue and Fatigue + Heat conditions respectively (p < 0.001; d = 0.62 - 0.69), with RPE increasing by 32% (Fatigue) and 46% (Fatigue + Heat) (p < 0.001; d = 1.31 - 2.39). Further, pre-simulation fatigue reduced both isometric mid-thigh pull and push-up peak forces (measured post-simulation) compared to control strength measures (p < 0.05; d = 0.18 - 0.27). This study highlights how physical fatigue hinders physical capabilities in a firefighting context.
Physiological measures have the potential to capture the dynamic nature of teamwork as it unfolds. Despite this potential, relatively few studies have applied physiological data in team contexts, leaving a gap in theory and practice. To address this gap, this work examines the following question: What are the emerging principles for using physiological measures to assess and diagnose team performance? To explore this question, we present an interrogative approach that structures the key considerations for applying physiological measures in team research. Specifically, this approach organizes considerations related to the purpose, context, personnel, timing, measurement selection, and implementation of using physiological measures to assess team performance. Building on prior guidance, we propose a set of emerging principles that synthesize best practices while introducing new considerations specific to the use of physiological data in team contexts. These principles provide practical guidance for researchers and practitioners seeking to leverage physiological measures, while emphasizing that their effective use depends on rigorous methodology, ethical safeguards, and integration with other validated assessment approaches.
Nurses experience substantial physical demands that increase their risk of work-related musculoskeletal disorders. Assistive devices may mitigate this risk, yet their use remains inconsistent. This cross-sectional study examined physical workload and assistive device utilization among nurses. A total of 456 licensed nursing professionals in Florida who provide direct patient care were included. Participants reported moderate to high physical workload. Among the 390 participants with frequency-of-use data, 51.0% (n=199) reported frequent assistive device use. Frequent assistive device use was more common among nurses with higher physical workload. Each 10-point increase in physical workload was associated with 22% higher odds of frequent assistive device use, after adjusting for demographic and employment characteristics. Common barriers to the use of assistive devices included limited availability, time constraints, and patient discomfort. Participants expressed interest in lightweight, easy-to-use, patient-friendly devices. These findings underscore the need for organizational strategies and user-centered design to support the adoption of assistive technologies and reduce occupational injury risk among nurses.
To understand the factors contributing to ill-fitting gear, this study investigated user perceptions across firefighters of different gender, service type, and pre-sizing measurement status. A total of 345 firefighters (19.8% women, 34.8% volunteer firefighters, and 18.0% not measured) completed an online survey collecting their perceptions on general and task-specific gear fit and movement limitations. The results indicated that women firefighters and firefighters without pre-sizing measurement reported significantly higher risk of ill-fitting gear. Firefighters of different gender, service type, and measurement status reported similar risks of mobility and range-of-motion limitations in gear. Task-specific questions further emphasized the challenges faced by women firefighters and the importance of pre-sizing measurement. The unique patterns from task-specific inquiries highlighted the need of occupational context when investigating turnout gear fit and movement limitations. Participants suggested several solutions to improve gear fit, including better accessibility of gender-specific patterns, improved sizing procedures, and more frequent gear fit checks.
Direct in-water rescue is a safety-critical task in which towing technique and rescue-support equipment may influence both rescuer workload and task output. This study compared physical workload, towing performance and physiological economy across four mannequin towing techniques: Extended Arm Tow, Double Armpit Tow, "Sailor" Technique Tow and Rescue Tube Tow. Eighteen male water lifeguards (age 18.8 ± 1.3 years; V˙O2max 56.1 ± 5.0 mL·kg-1·min-1) completed randomized 50-m towing trials after an incremental swimming test to determine maximal oxygen uptake. Towing velocity, gas-exchange variables, heart rate, peripheral oxygen saturation, perceived exertion, oxygen cost per meter and body-mass-normalized oxygen cost per meter were assessed. Rescue Tube Tow produced the highest mean towing velocity and the lowest body-mass-normalized oxygen cost per meter, indicating the most favourable workload-performance profile. Double Armpit Tow elicited the lowest time-based cardiorespiratory strain but did not optimize transport efficiency. Oxygen cost per meter may support ergonomic evaluation of workload-performance efficiency in rescue tasks.
Markerless motion capture has the potential to enhance ergonomic risk assessment, but evidence remains limited for occupational manual handling tasks of increasing complexity. This study compared a multi-view system (OpenCap) and a monocular system (MediaPipe) against a marker-based reference system (Vicon) for lifting kinematics. Outcomes were assessed using the Rapid Entire Body Assessment (REBA) risk assessment tool. Twenty healthy participants performed three two-handed lifting tasks of increasing complexity under controlled laboratory conditions. Errors increased by 15-30% from symmetrical to asymmetric multi-planar tasks, with both systems demonstrating lower error in the sagittal plane (RMSE = 9.9-31.2°) than in the frontal and transverse planes. Both systems were reliable for symmetrical lifting, including high REBA agreement, but validity declined for tasks involving trunk rotation and walking. MediaPipe showed lower error for trunk and proximal joints, whereas OpenCap performed better for distal kinematics, informing practical system selection.
ISO 2631-1 generally treats frequency-weighted acceleration measured at the seat-occupant interface as independent of operator posture, yet this assumption has rarely been examined explicitly. This study evaluates that assumption. Twenty-four participants were exposed to three-dimensional whole-body vibration on a machine operator seat while maintaining forward lean, reclined, and twisted postures. Despite constant base excitation vibrations, the seat-interface frequency-weighted RMS acceleration (FWRMS) differed significantly across postures (F = 0.871, R = 0.765, T = 0.845 m/s2; p < 0.001), with posture explaining 78% of variance. A sandbag surrogate experiment confirmed that body-weight redistribution alone, without neuromuscular involvement, produced an approximately 13% variation in FWRMS, linking postural load shift to altered seat suspension dynamics. When propagated through ISO 2631-1 exposure equations, this corresponds to an approximately 27% difference in allowable daily exposure duration. These findings highlight the need to incorporate posture into whole-body vibration standard 2631-1 and occupational vibration risk assessment.
Obesity is associated with increased risk of work-related musculoskeletal disorders; however, specific biomechanical effects during manual material handing (MMH) tasks remain unclear. This study examined the influence of body mass index (BMI) on shoulder and lumbar joint moments and postures during a lift/lower task and load transfer task. Sixty-three participants (29 male, 34 female), spanning normal weight to class III obesity, completed MMH tasks under varying load and distance conditions. Higher BMI was associated with greater lumbar and shoulder moments across tasks, with condition-dependent effects indicating loading did not increase uniformly with body size. During lifting, BMI-related increases in lumbar loading were most pronounced during floor-level lifts and under lighter load conditions, with effects amplified in males. During the load transfer, BMI increased shoulder moments, with stronger effects at lighter loads. Trunk and shoulder angles changed minimally, highlighting body composition as an important differential modifier of mechanical exposure during MMH.
Personal support workers (PSWs) experience high rates of musculoskeletal disorders (MSDs) likely due to physical task demand exposures. However, limited data exists describing the biomechanical demands of common PSW tasks. Therefore, we aimed to characterize biomechanical exposure metrics associated with common and demanding PSW work tasks. Twenty PSWs completed twelve lab-simulated tasks, where full body kinematics and kinetics were collected for all trials. A whole-body top-down rigid link modelling approach was used to calculate relevant biomechanical exposure metrics. Patient handling tasks resulted in the highest peak extensor moments, but lowest cumulative moments. Patient care tasks resulted in the highest cumulative extensor moments, but lower peak moments. Additionally, patient care tasks took longer to complete and required participants to frequently adopt more flexed low back postures. Study findings help us to better understand how task types influence biomechanical exposure metrics, an important precursor to the design of efficacious interventions.
Automated driving errors can threaten occupants’ psychological comfort, creating a need for effective in-vehicle recovery communication. Recovery strategies refer to communicative system responses delivered after automation errors to mitigate negative impacts and restore positive interaction. This mixed-methods study examined how four recovery strategies (explanation, apology, promise, and denial) and two speech styles (machine-like and human-like) influence occupants' psychological comfort, operationalized as perceived safety and pleasure, after an automation error. Thirty-four participants completed a within-subjects driving simulator experiment and semi-structured interviews. Explanation and promise most effectively improved both dimensions, whereas denial impaired occupant experience. Apology showed a style-dependent reversal: human-like apology increased pleasure but reduced perceived safety. Machine-like delivery produced stronger overall benefits for perceived safety, but speech-style effects depended on strategy content. These findings suggest that recovery communication should align strategy content with the informational demands of the event and the expressive register of delivery.
This work aimed to establish the relationship between seat back and seat pan angles to eliminate the seat pan shear force for a large range of seat configurations. Thirty-nine volunteers participated in the experiment. A reconfigurable experimental seat was used. Seven seat back angles ranging from 0 (vertical) to 60° were tested. For each, starting from a preferred seat pan angle self-selected by participants, an experimenter manually adjusted it so that the shear on the seat pan surface fell within [-5N, 5N] while the pelvis was controlled to keep in contact with the seat back. Results suggested a parabolic relationship between seat back and seat pan angles with a peak of about 14.9° at 40 degrees of seat back angle. On average, the zero-shear seat pan angle was 4.2° higher than the preferred one and the use of a leg support increased zero-shear angle by 4.4°.
Chronic wounds pose a growing global health challenge, impacting patients’ quality of life and straining health care systems. Grounded in the SEIPS framework, this study presents a longitudinal, whole-system exploration of a novel cross-sectoral intervention combining telemedicine and an ambulatory wound care team for chronic wound management in Norway. Baseline and fieldwork data collected across a regional hospital and six municipalities reveal dualities in organizational readiness and wound care competency, highlighting both barriers and opportunities for improving service delivery. The empirically informed CROSTAI model synthesizes these insights, offering a framework for redesigning health care systems and practices to improve the quality of wound care and patient and system outcomes. The study underscores the need for whole-system approaches to the exploration, planning, and implementation of complex new healthcare interventions, with associated redesign implications. This includes maintaining a continuous balance between negative and positive system outcomes and improving the alignment among organizations, technologies, environments, and actual clinical work, in which co-design, human-centered development, and systems-based evaluation are essential. The CROSTAI model, combined with the systematic research design that supports it, contributes to a broader understanding of human-centered design in complex health care systems and has potential for transferability to explorations in similar contexts.
Vocal fold injection procedures demand precise needle placement, yet limited intraoperative visualization creates dependence on practitioner experience. Building on a first-generation light-guided injection system, this study applied iterative usability engineering to address usability limitations. Otolaryngologists (n = 33) participated across three phases: design concept, three formative evaluations, and summative validation. Use-related risks were translated into user interface requirements. The prototype was developed and iteratively refined, with qualitative feedback revealing physical ergonomics and needle-handling as top design priorities. The second-generation device features a portable wireless design with contoured and textured grip surfaces, optimized Y-connector angle, light-intensity control dial, and balanced weight distribution. User satisfaction improved from 3.86 to 4.72 across evaluations, and summative validation (n = 15) demonstrated 100% task completion with one use error. These findings highlight the ergonomic design of handheld medical devices, the challenge of habit-driven use errors, and the significance of iterative usability evaluations.
Automated vehicle failures can undermine drivers’ trust and increase the risk of automation misuse or disuse. This study investigated the effects of vehicle voice assistant (VA) messages on trust repair following an automated-driving failure. Thirty-four drivers were categorized into two groups based on their initial Trust in Automated Driving (TiAD): Trustful (high TiAD) and Distrustful (low TiAD). After each automated-driving failure involving delayed pedestrian detection and abrupt emergency braking, participants received one of four repair strategies (apology, explanation, promise, or denial), delivered with or without interjections (e.g., wow, oops, hmm, oh), resulting in eight distinct VA messages (2 × 4). Trust ratings were collected across four driving scenarios, and participants also reported their preferences for the VA messages. Results showed that explanation was the most effective strategy for repairing trust, while denial was the least effective. Interjections alone did not directly facilitate repair trust. Distrustful participants demonstrated greater trust repair gains, suggesting a stronger need for corrective feedback. In preference ratings, the explanation strategy with interjections was selected as the most preferred among all VA messages. These findings provide practical guidance for designing VA trust-repair messages following automated-driving failures.
Commercial Dungeness crab fishing involves repetitive and physically demanding tasks that place fishermen at high risk for work-related musculoskeletal disorders (WMSDs), particularly in the low back. This study evaluated the effects of three commercially available passive back-support exoskeletons (BSEs) during simulated crab sorting and crab pot handling tasks. Twenty healthy male participants performed both tasks under four BSE conditions (two rigid, one soft, and no BSE) in a laboratory experiment. During the tasks, joint kinematics, muscle activity, and perceived exertion were measured. The rigid BSEs significantly reduced median erector spinae (ES) muscle activity during crab sorting by 15-23% relative to the no-BSE condition and also lowered low back perceived exertion. Similarly, the rigid devices reduced peak ES muscle activity by 6-17% during crab pot handling. The soft BSE produced small, non-significant effects on ES muscle activity during both tasks. In addition, BSE use also resulted in task- and device-specific changes in joint kinematics and the activation of some secondary muscles (e.g., leg and abdominal muscles). These findings suggest that passive BSEs, particularly rigid ones, can reduce low back demands during commercial crabbing tasks; however, their benefits vary across tasks and devices. Moreover, the potential biomechanical trade-offs in non-target body regions warrant further investigation.
This study investigated the air gaps, or ease, between the anterior female torso and two types of soft body armor, planar and nonplanar, using a novel 3D torso scanning method. To account for differences in breast morphology, participants who were professionally fitted into B-, D-, and F-cup bras were recruited for the study. After an initial scan was taken in the bra, the subjects were scanned wearing each type of armor without any other base layers. The bra scan was overlaid with the armor scans and the difference between the two at six landmarks (left nipple, right nipple, midpoint between the nipples, xiphoid process, and the left and right cup-strap intersections on the bra) quantified the air gap depth or compression at each point. Although air gap measurement did not significantly differ by bra size, the nonplanar armor produced significantly larger gaps than the planar armor, suggesting that the contoured, nonplanar design for females better accommodates breast morphology. These findings quantify the air gap depth between the female and her armor and provide empirical data to inform body armor testing protocols on the female anterior torso.
The SAFE (System for Activity-aware Fatigue Evaluation) framework integrates wearable sensing, biomechanical modelling, and task detection to enable monitoring of operator endurance and ergonomic risk. In this feasibility study, the framework was evaluated offline in a laboratory environment with 10 participants performing industry-type tasks, combining inertial measurement units (IMUs), pressure insoles, a torque-based endurance model, task classification, and a custom application. Validation against motion capture confirmed that IMU-derived joint angles were within acceptable error ranges for endurance estimation. The framework produced endurance metrics that distinguished between ergonomically high- and low-risk tasks (P < .05) and correlated strongly with subjective fatigue ratings (rmm≥.878, P < .001). IMUs captured arm movement variability across dynamic tasks and task classification via pressure insole data enabled the application of task-specific endurance coefficients. These results demonstrate that the SAFE framework is a feasible predictive method for online operator monitoring and ergonomic risk assessment, providing a foundation for future real-time deployment.
