Effect of Notebook Computer Display Tilt Angle on Muscle Activity among Notebook User (original) (raw)
Related papers
International Journal of Industrial Ergonomics, 2002
More constrained posture and higher neck muscle activities have been reported among users of notebook computers than those of desktop computers. Complaints of eye and musculoskeletal discomfort as well as difficulty of keying were greater during work with notebook computers. These reports ascribed the findings to the differences in the size of desktops and notebooks. Another ergonomic aspect of the notebook computer distinct from the CRT is its angledependent luminance contrast. The present study investigated the effects of liquid crystal display (LCD) tilt angle of a notebook computer on posture, muscle activities and somatic complaints in 10 subjects. At the tilt angle of 1001, the subjects were noted to have relatively less neck flexion. The static neck extensor muscle activity was also lowest at this tilt angle. Nonetheless, the complaint survey revealed higher rates of discomfort while viewing and using the LCD set at the tilt angle of 1001. The findings of this study strongly suggested that the ergonomic features and problems attributable to notebook computers are distinct from the desktop computers. The points of interest raised in this paper should be considered when contemplating the use of notebook computers.
INDUSTRIAL HEALTH, 1998
The advent of compact and lightweight portable personal computers has offered its users mobility. Various sizes of PC-FPDs can now be seen in the occupational setting as an alternative to the desktop computers. However, the increasing popularity of this relatively new technology may not be without any accompanying problems. The present study was designed to evaluate the use of PC-FPDs in terms of postural changes, muscle load, subjective complaints and performance of the subjects. Ten subjects, 5 males and 5 females, were asked to perform a text-entry task for 5 minutes using each of the 5 types of personal computers-1 desktop and 4 PC-FPDs of various sizes. Results showed that the posture assumed by the subjects while using the PC-FPDs was significantly more constrained than that assumed during work with the desktop computer. Viewing and neck angles progressively lowered and the trunk became more forward inclined. The EMG results also revealed that the activities of the neck extensor in PC-FPDs were significantly higher than in the desktop computers. Trends of increasing discomfort and difficulty of keying with the use of smaller PC-FPDs were noted. Performance was significantly lower for smaller PC-FPDs. This study shows that PC-FPDs have ergonomic attributes different from the desktop computer. An ergonomic guideline specific for PC-FPDs users is needed to prevent the surge in health disorders previously seen among desktop computer users.
Applied Ergonomics, 2009
Desk design and computer display height can affect posture and muscle activation during computer use. Amplitudes of postural variables and muscle activity during computer use do not explain the results from epidemiological studies of musculoskeletal discomfort and disorders related to computer use. The purpose of this study was to assess variability of posture and muscle activity during work with two computer display heights and book/paper, in conjunction with a curved desk designed to provide forearm support and a traditional, straight desk. 18 male and 18 female participants performed 10-min tasks involving keying, mousing, reading and writing in six desk/display conditions. 3D posture and surface emg were assessed for the final 2 min of each task. The curved desk resulted in greater postural and muscle activity variation, suggesting an advantage of this supportive surface over the straight desk. There was little difference in variability associated with the two display heights. However, greater variability of posture and muscle activity was evident with the book/paper condition. Non-touch typists had greater neck flexion variation. The design of information technology tasks and workstations can influence the short term variation in posture and muscle activity. Variation is influenced independently of mean postures and muscle amplitudes and therefore needs to be considered to adequately assess the risk of musculoskeletal disorders. Crown
Effects of portable computing devices on posture, muscle activation levels and efficiency
Applied ergonomics, 2014
Very little research exists on ergonomic exposures when using portable computing devices. This study quantified muscle activity (forearm and neck), posture (wrist, forearm and neck), and performance (gross typing speed and error rates) differences across three portable computing devices (laptop, netbook, and slate computer) and two work settings (desk and computer) during data entry tasks. Twelve participants completed test sessions on a single computer using a test-rest-test protocol (30min of work at one work setting, 15min of rest, 30min of work at the other work setting). The slate computer resulted in significantly more non-neutral wrist, elbow and neck postures, particularly when working on the sofa. Performance on the slate computer was four times less than that of the other computers, though lower muscle activity levels were also found. Potential or injury or illness may be elevated when working on smaller, portable computers in non-traditional work settings.
Characterization of posture and comfort in laptop users in non-desk settings
Applied Ergonomics, 2012
Laptop computers may be used in a variety of postures not coupled to the office workstation. Using passive motion analysis, this study examined mean joint angles during a short typing/editing task in college students (n ¼ 20), in up to seven positions. Comfort was assessed after task execution through a body map. For three required postures, joint angles in a prone posture were different than those while seated at a couch with feet either on floor or on ottoman. Specifically, the prone posture was characterized by comparatively non-neutral shoulders, elbows and wrists, and pronounced neck extension. Significantly greater intensity and more regions of discomfort were marked for the prone posture than for the seated postures. It is recommended that the prone posture only be assumed briefly during laptop use. Exposure to laptops outside of the office setting should be assessed in future epidemiologic studies of musculoskeletal complaints and computer use.
Iranian Journal of Public Health, 2016
Background: Workstation design has shift from using single monitor screen to dual monitor screens, which may impose some impacts towards the muscles activity. This study aimed to determine the effect of using dual monitor screen computer to the neck-shoulder muscle activity among computer user. Method: This experimental study was conducted in 2015 among 28 healthy students in University Malaysia Perlis. The muscle activity of sternocleidomastoid and trapezius were recorded using surface electromyography (sEMG) as the participants perform two types of computer task: (1) proofreading task for 10 minutes (2) typing task for 20 minutes in setting; single and dual monitor screens. Results: There was a significant reduction in the median frequency of the left trapezius muscle (t=-2.515, P=0.018). Sternocleidomastoid muscle activity for both sides also showed a significant reduction in the median frequency where right SCM (t=-2.579, P=0.016) and left SCM (t=-2.345, P=0.027). When compared ...
Journal of Electromyography and Kinesiology, 2008
Computer display height and desk design to allow forearm support are two critical design features of workstations for information technology tasks. However there is currently no 3D description of head and neck posture with different computer display heights and no direct comparison to paper based information technology tasks. There is also inconsistent evidence on the effect of forearm support on posture and no evidence on whether these features interact. This study compared the 3D head, neck and upper limb postures of 18 male and 18 female young adults whilst working with different display and desk design conditions. There was no substantial interaction between display height and desk design. Lower display heights increased head and neck flexion with more spinal asymmetry when working with paper. The curved desk, designed to provide forearm support, increased scapula elevation/protraction and shoulder flexion/ abduction.
Applied Ergonomics, 2014
This study evaluated the impact on neck movement and muscle activity of placing documents in three commonly used locations: in-line, flat desktop left of the keyboard and laterally placed level with the computer screen. Neck excursion during three standard head movements between the computer monitor and each document location and neck extensor and upper trapezius muscle activity during a 5 min typing task for each of the document locations was measured in 20 healthy participants. Results indicated that muscle activity and neck flexion were least when documents were placed laterally suggesting it may be the optimal location. The desktop option produced both the greatest neck movement and muscle activity in all muscle groups. The in-line document location required significantly more neck flexion but less lateral flexion and rotation than the laterally placed document. Evaluation of other holders is needed to guide decision making for this commonly used office equipment.
INDUSTRIAL HEALTH, 1997
The effects of the VDT screen height on working posture and electromyographic (EMG) activities of the neck and shoulder muscles were determined in 10 healthy subjects. The subjects performed a mouse-driven interactive task at the screen height settings of 80,100 and 120 cm. Changes in body positions were measured by video image and frame analysis. Surface EMG recordings were done on the neck extensor muscle and the descending part of the trapezius muscle, both on the right side. The results of the postural analysis showed that at higher screen height sittings, the neck became significantly more erect. The subjects also assumed a more backwardleaning trunk position at higher screen heights. The EMG activities of the neck and shoulder muscles were related to the neck angle and trunk inclination, respectively. A more flexed neck produced significantly higher neck extensor muscle activities. A backward-leaning trunk was also noted to decrease trapezius muscle activity in some subjects.
2018
Purpose: The present study aimed to compare Musculoskeletal Discomforts (MSDs) among six different common postures while working with laptop in female students of University of Tehran, Tehran City, Iran. Methods: This was a crossover trial study. Eighteen female students voluntarily and purposefully participated in all stages of the study. The study participants were randomly assigned into groups to work for 10 minutes on different postures for laptop use during six continuous nights. MSDs was measured each night after 10 minutes of laptop use. For this purpose, Van der Grinten and Smith (1992) method was applied. The obtained data were analyzed by repeated measures oneway ANOVA at a significance level of P≤0.05, in SPSS. Results: The obtained results suggested a significant difference among six working postures in MSDs (P=0.005). The results of Bonferroni post hoc analysis revealed that the highest level of MSDs was observed in a cross-legged sitting position on the floor. While, the lowest level of MSDs was found in the sitting on a chair posture. In addition, the study participants who used a desk in order to increase the height of the laptop, reported less levels of MSDs than laptop use in the cross-legged position on the floor (P=0.039) or sitting on the bed (P=0.011). Conclusion: According to this study, in order to minimize MSDs during working with laptop, it is recommended to use desk and chairs instead of sitting cross-legged on the floor or bed.