| 1. |
- Domkin, Dmitry, et al.
(författare)
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Effect of ciliary-muscle contraction force on trapezius muscle activity during computer mouse work
- 2019
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Ingår i: European Journal of Applied Physiology. - : SPRINGER. - 1439-6319 .- 1439-6327. ; 119:2, s. 389-397
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Tidskriftsartikel (refereegranskat)abstract
- The present study aimed to identify whether or not an increase in ciliary-muscle contraction force, when the eye-lens is adjusted for viewing at a near distance, results in an increase in trapezius muscle activity, while performing a natural work task. Twelve participants, ranging in age from 21 to 32years, performed a computer-mouse work task during free gaze conditions. A moving visual target was tracked with a computer mouse on a screen placed at two different distances from the eyes, 25cm and 50cm. Tracking performance, eye accommodation, and bilateral trapezius muscle activity were measured continuously. Ciliary-muscle contraction force was computed according to a formula which takes into account the age-dependent, non-linear relationship between the contraction force of the ciliary muscle and the produced level of eye accommodation. Generalized estimating equations analyses were performed. On the dominant hand side and for the nearest screen distance, there was a significant effect of ciliary-muscle contraction force on the trapezius muscle activity (p<0.001). No other effects were significant (p>0.05). The results support the hypothesis that high visual demands, during computer mouse work, increase ciliary muscle contraction force and contribute to a raise of the sustained level of trapezius muscle activity. The current study specifically clarifies the validity of the relationship between ciliary-muscle contraction force and trapezius muscle activity and demonstrates that this relationship is not due to a general personality trait. We conclude that a high level of ciliary muscle contraction force can contribute to a development of musculoskeletal complaints in the neck-shoulder area.
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| 2. |
- Richter, Hans O., et al.
(författare)
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Eye-lens accommodation load and static trapezius muscle activity
- 2011
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 111:1, s. 29-36
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this experimental study was to investigate if sustained periods of oculomotor load impacts on neck/scapular area muscle activity. The static trapezius muscle activity was assessed from bipolar surface electromyography, normalized to a submaximal contraction. Twenty-eight subjects with a mean age of 29 (range 19–42, SD 8) viewed a high-contrast fixation target for two 5-min periods through: (1) -3.5 dioptre (D) lenses; and (2) 0 D lenses. The target was placed 5 D away from the individual’s near point of accommodation. Each subject’s ability to compensate for the added blur was extracted via infrared photorefraction measurements. Subjects whose accommodative response was higher in the -D blur condition (1) showed relatively more static bilateral trapezius muscle activity level. During no blur (2) there were no signs of relationships. The results indicate that sustained eye-lens accommodation at near, during ergonomically unfavourable viewing conditions, could possibly represent a risk factor for trapezius muscle myalgia.
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| 3. |
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| 4. |
- Richter, Hans O., et al.
(författare)
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Stabilization of gaze : A relationship between ciliary muscle contraction and trapezius muscle activity
- 2010
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Ingår i: Vision Research. - : Elsevier BV. - 0042-6989 .- 1878-5646. ; 50:23, s. 2559-2569
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Tidskriftsartikel (refereegranskat)abstract
- In an experimental study four levels of oculomotor load were induced binocularly. Trapezius muscle activity was measured with bipolar surface electromyography and normalized to a submaximal contraction. Twenty-eight subjects with a mean age of 29 (range 19–42, std 8) viewed a high-contrast fixationt arget for four 5-min periods through: (i) 3.5 dioptre (D) lenses; (ii) 0 D lenses; (iii) individuallya djusted prism D lenses (1–2 D base out); and (iv) +3.5 D lenses. The target was placed close to thei ndividual’s age-appropriate near point of accommodation in conditions (i–iii) and at 3 m in condition( iv). Each subject’s ability to compensate for the added blur was extracted via infrared photorefraction measurements. A bitwise linear regression model was fitted on group level with eye-lens refraction on the x-axis and normalized trapezius muscle EMG (%RVE) on the y -axis. The model had a constant level of trapezius muscle activity – where subjects had not compensated for the incurred defocus by a change in eye-lens accommodation – and a slope, where the subjects had compensated. The slope coefficient was significantly positive in the D (i) and the +D blur conditions (iv). During no blur (ii) and prism blur (iii) there were no signs of relationships. Nor was there any sign of relationship between the convergence response and trapezius muscle EMG in any of the experimental conditions. The results appear directly attributable to an engagement of the eye-lens accommodative system and most likely reflect sensorimotor processing along its reflex arc for the purpose of achieving stabilization of gaze
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| 5. |
- Richter, Hans O., et al.
(författare)
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Long-term adaptation to neck/shoulder pain and perceptual performance in a hand laterality motor imagery test
- 2010
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Ingår i: Perception. - : Sage Publications. - 0301-0066 .- 1468-4233. ; 39:1, s. 119-130
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Tidskriftsartikel (refereegranskat)abstract
- The effect of neck/shoulder pain on the performance in a hand laterality motor imagery test was studied. Responses to the Cooper and Shepard (1975, Journal of Experimental Psychology: Human Perception and Performance 104 48–56) hand laterality test were explored in twenty-four individuals with chronic non-specific neck pain and twenty-one subjects with chronic neck pain of traumatic origin (whiplash-associated disorder). Twenty-two controls were also included in the study. Digitalised right- or left-hand stimuli were presented at five different stimulus angles (0°, 45° laterally, 90° laterally, 135° laterally, and 180°). The experimental task was to decide the laterality as fast and accurately as possible. The performance, both reaction time (RT) and accuracy, of the two experimental groups was contrasted with that of the control group. The main results revealed that the subjects afflicted with whiplash injury on the average exhibited a faster response pattern than symptom-free healthy controls. Despite their musculoskeletal deficits and experience of pain these volunteers also exhibited a preserved speed–accuracy tradeoff. Longer duration of time with symptoms of neck pain was, moreover, associated with progressively faster RTs. These results point to perceptual learning and may reflect different stages of adaptation to neck pain.
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| 6. |
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| 7. |
- Lundqvist, Lars-Olov, 1958-, et al.
(författare)
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Effects of Feldenkrais Method on Chronic Neck/Scapular Pain in People With Visual Impairment : A Randomized Controlled Trial With One-Year Follow-Up
- 2014
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Ingår i: Archives of Physical Medicine and Rehabilitation. - : Saunders Elsevier. - 0003-9993 .- 1532-821X. ; 95:9, s. 1656-1661
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To determine whether the Feldenkrais method is an effective intervention for chronic neck/scapular pain in patients with visual impairment.Design: Randomized controlled trial with an untreated control group.Setting: Low vision center.Participants: Patients (N=61) with visual impairment (mean, 53.3y) and nonspecific chronic (mean, 23.8y) neck/scapular pain.Interventions: Participants were randomly assigned to the Feldenkrais method group (n=30) or untreated control group (n=31). Patients in the treatment group underwent one 2-hour Feldenkrais method session per week for 12 consecutive weeks.Main Outcome Measures: Blind assessment of perceived pain (visual analog scale [VAS]) during physical therapist palpation of the left and right occipital, upper trapezius, and levator scapulae muscle areas; self-assessed degree of pain on the Visual, Musculoskeletal, and Balance Complaints questionnaire; and the Medical Outcomes Study 36-Item Short-Form Health Survey bodily pain scale.Results: Patients undergoing FeldenIcrais method reported significantly less pain than the controls according to the VAS and Visual, Musculoskeletal, and Balance Complaints questionnaire ratings at posttreatment follow-up and 1-year follow-up. There were no significant differences regarding the Medical Outcomes Study 36-Item Short-Form Health Survey bodily pain scale ratings.Conclusions: Feldenkrais method is an effective intervention for chronic neck/scapular pain in patients with visual impairment. (c) 2014 by the American Congress of Rehabilitation Medicine
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| 8. |
- Richter, Hans O., et al.
(författare)
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Eye-neck interactions triggered by visually deficient computer work
- 2011
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Ingår i: Work. - : IOS Press. - 1051-9815 .- 1875-9270. ; 39:1, s. 67-78
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To study the joint occurrence of eye-and-neck/scapular area symptoms and their association with occupational risk factors in a cross-sectional sample of professional information technology users.Study population: The participants consisted of 3,971 employees who worked with computers for a minimum of one hour a day. 2,551 (73%) were men and 945 (27%) women, with an age range of 18 up to 64 years. The mean age was 38.1 (SD = 10.7) for men and 37.6 (SD = 12.0) for the women. The measures were obtained via a self-administered survey in combination with a visual examination conducted by an optometrist.Methods: Two complementary logistic regression analyses with forced entry was conducted on n = 3,496 (88% adjusted response rate) cases. The effect of ocular symptoms on the risk of reporting musculoskeletal symptoms, or vice versa, was examined first in two separate binominal logistic regression analyses. Age, Gender, Near work variable and Visual functioning variables were included in these analyzes. Variables associated with the risk of developing an increase in either symptom category were also examined in two additional binomial logistic regression analyses.Results: Exposure to spectacles (single vision, multifocal, or progressive correction) in combination with a visual acuity < 1 surfaced as a key mediator of symptoms from the neck/scapular area (p < 0.01). A vergence disparity (uncompensated vergence error) similarly was associated with an augmented risk of developing an increase in neck/scapular area symptoms (p < 0.05). The most influential risk factor for neck/scapular area symptoms were ocular symptoms and vice versa (p < 0.0001).Conclusions: The results support the hypothesis which postulates that eye-neck/scapular area symptoms interaction may be due to a functional coupling from and between the eye-neck/scapular area muscles [28].
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| 9. |
- Zetterberg, Camilla, 1970-
(författare)
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The impact of visually demanding near work on neck/shoulder discomfort and trapezius muscle activity : Laboratory studies
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: Musculoskeletal discomfort in the neck and shoulders is common among workers performing visually demanding near work, e.g., on a computer screen, and sustained low-level muscle activity during such work can lead to work-related pain. The relationships between visual demands and muscle activity and discomfort in the neck/shoulder region are at present unclear. Aim: The aims of this thesis were to determine whether neck/shoulder discomfort and trapezius muscle activity increases during visually demanding experimental near work, and to investigate whether eye-lens accommodation is a mediating mechanism behind increased trapezius muscle activity. Methods: The four papers included are based on two experiments with different visually demanding near work tasks (duration 5 and 7 min). Trial lenses of different diopters were used to manipulate the visual demands (i.e., induce more or less accommodation) and thereby create different viewing conditions. Monocular viewing, which does not require active convergence, was used to examine the isolated effect of accommodation. Eye-lens accommodation and trapezius muscle activity were measured continuously during the visual tasks, and in one experiment the participants rated their eye and neck/shoulder discomfort at baseline and after each visual task. Results: Neck/shoulder discomfort and trapezius muscle activity increased during the visually demanding near work and participants experiencing a greater increase in eye discomfort (compared with baseline) also developed more neck/shoulder discomfort with time. There were no significant differences in muscle activity among the viewing conditions, and no effect of isolated accommodation response within the monocular viewing conditions. Conclusion: These findings indicate that accommodation per se is unlikely to mediate trapezius muscle activity. Instead, the increase in trapezius muscle activity observed here may be due to a combination of high visual attention and enhanced requirement for eye-neck (head) stabilisation. Since these results suggest that neck/shoulder discomfort may aggravate with time when the visual demands are high, it is important to provide good visual conditions in connection with visually demanding occupations.
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| 10. |
- Zetterlund, Christina, 1956-, et al.
(författare)
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Visual, Musculoskeletal, and Balance Complaints in AMD : A Follow-Up Study
- 2016
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Ingår i: Journal of Ophthalmology. - New York, USA : Hindawi Limited. - 2090-004X .- 2090-0058. ; 2016
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Tidskriftsartikel (refereegranskat)abstract
- Purpose. To investigate whether patients with age-related macular degeneration (AMD) run a potentially higher risk of developing visual, musculoskeletal, and balance complaints than age-matched controls with normal vision. Methods. Visual assessments, self-rated visual function, self-rated visual, musculoskeletal, and balance complaints, and perceived general health were obtained in 37 AMD patients and 18 controls, at baseline and after an average of 3.8 years later. Results. At follow-up both groups reported decreased visual acuity (VA) and visual function, but only AMD patients reported significantly increased visual, musculoskeletal, and balance complaints. Decreased VA, need for larger font size when reading, need for larger magnification, and decreased self-rated visual function were identified as risk markers for increased complaints in AMD patients. These complaints were also identified as risk markers for decreased health. For controls, decreased VA and self-reported visual function were associated with increased visual and balance complaints. Conclusions. Visual deterioration was a risk marker for increased visual, musculoskeletal, balance, and health complaints in AMD patients. Specifically, magnifying visual aids, such as CCTV, were a risk marker for increased complaints in AMD patients. This calls for early and coordinated actions to treat and prevent visual, musculoskeletal, balance, and health complaints in AMD patients.
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