Does treadmill workstation use affect user’s kinematic gait symmetry?

The effects of treadmill workstation use on kinematic gait symmetry and computer work performance remain unclear. The purpose of this pilot study was to analyze the effects of treadmill workstation use on lower body motion symmetry while performing a typing task when compared to overground and treadmill walking. The lower body motion of ten healthy adults (6 males and 4 females) was recorded by a motion capture system. Hip, knee, and ankle joint rotations were computed and compared for each condition. Despite comparable lower body kinematic gait asymmetries across conditions, asymmetric knee flexion motions at early gait cycle were only found in treadmill workstation users (left knee significantly more flexed than the right one). This demonstrates that the interaction between walking and another task is dependent on the task cognitive content. Our findings suggest that lower body kinematic gait symmetry may be influenced by the use of treadmill workstations.

Ergonomic design and evaluation of a novel laptop desk for wheelchair users

BACKGROUND: Nowadays, although using laptops to perform many routine activities is inevitable, many wheelchair users are not able to efficiently use their laptops due to their movement limitations and inappropriate workstations. OBJECTIVE: The purpose of this study was to design and evaluate a novel ergonomic laptop desk for wheelchair users by considering their movement limitations. METHODS: In this experimental study, we ergonomically designed and assessed a novel laptop desk in two phases in a laboratory. In the first phase of the study, design specifications were identified by an expert panel and, accordingly, a new laptop desk was designed and prototyped for the wheelchair users. In the second phase, in order to evaluate the laptop desk, 14 wheelchair users were asked to complete a typing task within 20 minutes, both with and without using the laptop desk. Postural risk level, perceived discomfort, and task performance were evaluated using the Rapid Upper Limb Assessment (RULA) technique, Local Perceived Discomfort (LPD) questionnaire, and the number of letters typed and typing errors, respectively. RESULTS: The postures of the wrist, arm, and neck regions were corrected from RULA action level 3 to 2 when the designed laptop desk was used. In addition, the average perceived discomfort of the participants significantly decreased in the neck, shoulder, and wrist regions. Furthermore, typing accuracy was improved significantly when novel laptop desk was used. CONCLUSIONS: Accommodating wheelchair user workstation by using the novel designed laptop desk could reduce musculoskeletal disorders risk factors and help wheelchair users to perform their work more efficiently.

Too Much of a Good Thing is Just About Right: Using Penalty Analysis to Evaluate the Impact of Key Travel on Notebook Keyboard User Experience

Penalty analysis (PA) is a common sensory data analysis method used to develop and improve consumer products. This technique identifies the factors that lead to the greatest reduction in product satisfaction with the largest agreement among participants. Here, we apply PA to a usability study with 51 representative users comparing two different notebook computers with different key travel (1mm vs. 1.5mm). Participants completed a typing task followed by a usability survey. While traditional t-tests revealed limited differences between keyboards, PA identified additional ways to optimize the keyboard by adjusting attributes such as key travel and force. Overall, PA may be a useful complement to usability studies. Recommendations for adapting PA to usability studies will be discussed including advantages and limitations.

Sitting Posture during Prolonged Computer Typing with and without a Wearable Biofeedback Sensor

Prolonged sitting combined with an awkward posture might contribute to the increased risks of developing spinal pain. Maintaining an upright sitting posture is thus often suggested, especially nowadays when people spend longer periods in the sitting posture for occupational or leisure activities. Many types of assistive devices are commercially available to help computer users maintain an upright sitting posture. As the technology advances, wearable sensors that use microelectromechanical technology are designed to provide real-time biofeedback and promote adjusting posture actively. However, whether such wearable biofeedback sensors could assist adjusting sitting posture in computer users during prolonged typing remains unknown. This study aimed to investigate the effects of a wearable biofeedback sensor on maintaining an upright sitting posture. Twenty-one healthy young adults were recruited and performed a 1-h computer typing task twice, with and without using the active biofeedback device. The sagittal spinal posture during computer typing was measured using a three-dimensional motion analysis system. Using the wearable biofeedback sensor significantly decreased the neck flexion (p < 0.001), thoracic kyphotic (p = 0.033), and pelvic plane (p = 0.021) angles compared with not using the sensor. Computer users and sedentary workers may benefit from using wearable biofeedback sensors to actively maintain an upright sitting posture during prolonged deskwork.

Practice modifies the response to errors during a novel motor sequence learning task

The occurrence of an error when performing a motor sequence causes an immediate reduction in speed on subsequent trials, which is referred to as post-error slowing. However, understanding how post-error slowing changes with practice has been difficult because it requires extended practice on a novel sequence task. To address this issue, we examined post-error slowing in a novel glove-based typing task that participants performed for 15 consecutive days. Speed and accuracy improved from the early to middle stages of practice, but did not show any further improvements between middle and late stage of practice. However, when we analyzed the response to errors, we found that participants decreased both the magnitude and duration of post-error slowing with practice, even after there were no detectable improvements in overall task performance. These results indicate that learning not only improves overall task performance but also modifies the ability to respond to errors.

Thermal behavior of the skin region of the wrist and finger extensor muscles during a typing task

Background: Occupational diseases are the second leading cause of sick leave in Brazil, among which musculoskeletal disorders are very common especially among workers whose job includes typing tasks. Thermography analyzes the temperature distribution on the skin surface and is used for diagnosis and prevention of musculoskeletal disorders. Objective: To investigate the thermal behavior of the skin on the wrist and finger extensor muscle area before, during and after a typing task. Methods: Twenty-four workers whose job involves typing were allocated to two groups—with or without elbow, forearm or injury—and performed a 10-minute typing task. Four thermography images were captured from the forearms and fingers at baseline, 0–2, 3–5 and 8–10 minutes and the minimum, maximum and mean temperature was calculated. The data were subjected to factorial ANOVA with software SPSS v 20.0. The significance level was set to 5%. Results: Minimum (mean difference–d=1.7), maximum (d=0.8) and mean (d=0.39) temperature was lowest on the elbow of participants with forearm injury; maximum temperature was lower on the right compared to the left side (d=0.39). Temperature did not vary as a function of time. Conclusion: There was difference in skin temperature between individuals with or without forearm injury and between the right and left sides, but not as a function of time. In future studies tasks should be longer and/or have set typing speed and goals.

0104 The Effect of Time, Sleep, and Wake on Motor Memory Consolidation: A Partial Replication of Walker, Et Al. (2002)

Introduction Findings from Walker, et al (2002) ‘Practice with Sleep Makes Perfect: Sleep-Dependent Motor Skill Learning’ demonstrate that performance on a widely used motor memory task (motor sequence task (MST)) benefits from a 12hr period of sleep (and not wake) even if the sleep period does not occur for approximately 12hrs after task acquisition, suggesting that sleep is crucial for motor memory consolidation. Using a larger sample, we attempted to replicate this finding, which is derived from Groups B & D from Walker et al (2002). Methods Participants (64 medical students: Age 21.2±0.8; N=33 females) were trained on the MST in the morning (10am; N=40) or evening (10pm; N=24) and then returned 12 and 24hrs later to be retested. The MST is a simple typing task that requires participants, at training, to type a 5-digit sequence (e.g., 4-1-3-2-4) as fast and accurately as possible over a series of 12 30-second trials with a 30-second break between each trial. At each retest, participants performed three 30-second trials. Results With 75% of the data collected we have found that when sleep follows training in the evening (first 12hr interval), the number of correctly typed sequences increased by 19.1% (cf. 20.5% in Walker (2002)). After a subsequent day of wake (second 12hr interval) performance increased by an additional 7.3% (cf. 2.0%). However, when a day of wake spanned the first 12hrs following training, performance increased by 14.5% (cf. 3.9%) followed by another 14.5% increase over the subsequent night (cf. 14.4%). Performance differences between sleep and wake participants were nonsignificant over the first 12hrs (p=0.38) and second 12hrs (p=0.49). Conclusion With most of data collection complete, our findings only partially replicate those of Walker et al (2002), and may draw into question the robustness of sleep for the processing motor memory. Support None

Errors in Imagined and Executed Typing

In motor imagery (MI), internal models may predict the action effects. A mismatch between predicted and intended action effects may result in error detection. To compare error detection in MI and motor execution (ME), ten-finger typists and hunt-and-peck typists performed a copy-typing task. Visibility of the screen and visibility of the keyboard were manipulated. Participants reported what type of error occurred and by which sources they detected the error. With covered screen, fewer errors were reported, showing the importance of distal action effects for error detection. With covered screen, the number of reported higher-order planning errors did not significantly differ between MI and ME. However, the number of reported motor command errors was lower in MI than in ME. Hence, only errors that occur in advance to internal modeling are equally observed in MI and ME. MI may require more attention than ME, leaving fewer resources to monitor motor command errors in MI. In comparison to hunt-and-peck typists, ten-finger typists detected more higher-order planning errors by kinesthesis/touch and fewer motor command errors by vision of the keyboard. The use of sources for error detection did not significantly differ between MI and ME, indicating similar mechanisms.