2018-07-01 12:00 - Messages

The effect of a passive trunk exoskeleton on functional performance in healthy individuals

The objective of this study was to assess the effect of a passive trunk exoskeleton on functional performance for various work related tasks in healthy individuals.
18 healthy men performed 12 tasks. Functional performance in each task was assessed based on objective outcome measures and subjectively in terms of perceived task difficulty, local and general discomfort.
Wearing the exoskeleton tended to increase objective performance in static forward bending, but decreased performance in tasks, such as walking, carrying and ladder climbing. A significant decrease was found in perceived task difficulty and local discomfort in the back in static forward bending, but a significant increase of perceived difficulty in several other tasks, like walking, squatting and wide standing. Especially tasks that involved hip flexion were perceived more difficult with the exoskeleton.
Design improvements should include provisions to allow full range of motion of hips and trunk to increase versatility and user acceptance.

Source: Baltrusch, S. J., van Dieën, J. H., van Bennekom, C. A. M. et Houdijk, H. (2018). Applied ergonomics, 72, 94-106.

Visual and psychological stress during computer work in healthy, young females - physiological responses

Purpose: Among computer workers, visual complaints, and neck pain are highly prevalent. This study explores how occupational simulated stressors during computer work, like glare and psychosocial stress, affect physiological responses in young females with normal vision.
Methods: The study was a within-subject laboratory experiment with a counterbalanced, repeated design. Forty-three females performed four 10-min computer-work sessions with different stress exposures: (1) minimal stress; (2) visual stress (direct glare); (3) psychological stress; and (4) combined visual and psychological stress. Muscle activity and muscle blood flow in trapezius, muscle blood flow in orbicularis oculi, heart rate, blood pressure, blink rate and postural angles were continuously recorded. Immediately after each computer-work session, fixation disparity was measured and a questionnaire regarding perceived workstation lighting and stress was completed.
Results: Exposure to direct glare resulted in increased trapezius muscle blood flow, increased blink rate, and forward bending of the head. Psychological stress induced a transient increase in trapezius muscle activity and a more forward-bent posture. Bending forward towards the computer screen was correlated with higher productivity (reading speed), indicating a concentration or stress response. Forward bent posture was also associated with changes in fixation disparity. Furthermore, during computer work per se, trapezius muscle activity and blood flow, orbicularis oculi muscle blood flow, and heart rate were increased compared to rest.
Conclusions: Exposure to glare and psychological stress during computer work were shown to influence the trapezius muscle, posture, and blink rate in young, healthy females with normal binocular vision, but in different ways. Accordingly, both visual and psychological factors must be taken into account when optimizing computer workstations to reduce physiological responses that may cause excessive eyestrain and musculoskeletal load.

Source: Mork, R., Falkenberg, H. K., Fostervold, K. I. et Thorud, H. M. S. (2018). International archives of occupational and environmental health.

Blood Pressure Response to Interrupting Workplace Sitting Time With Non-Exercise Physical Activity

Results of a 12-month Cohort Study
Objective: To evaluate the blood pressure (BP) effects of a yearlong e-health solution designed to interrupt prolonged occupational sitting time.
Methods: BP data of 228 desk-based employees (45.1 ± 10.5 years) were analyzed at baseline, 3, 6, 9, and 12 months.
Results: Systolic BP significantly reduced from baseline for the first 9 months (1.0 to 3.4 mmHg; P < 0.01) while diastolic and mean arterial pressure decreased for the full 12-months (4 to 5 mmHg for diastolic pressure and 3.6 to 4.2 mmHg for MAP; all P < 0.01).
Participants used the e-health solution 5.5 ± 2.0 times/day in the first 3 months which reduced to 4.2 ± 2.5 times/day by the end of the study (P < 0.05).
Conclusions: An e-health solution designed to increase non-exercise physical activity by interrupting sitting time in the workplace is feasible and produced long-term reductions in blood pressure.

Source: Mainsbridge, C., Ahuja, K., Williams, A., Bird, M. L., Cooley, D. et Pedersen, S. J. (2018). Journal of occupational and environmental medicine.

Dose-response relationship between cumulative physical workload and osteoarthritis of the hip

A meta-analysis applying an external reference population for exposure assignment
Background: There is consistent evidence from observational studies of an association between occupational lifting and carrying of heavy loads and the diagnosis of hip osteoarthritis. However, due to the heterogeneity of exposure estimates considered in single studies, a dose-response relationship between cumulative physical workload and hip osteoarthritis could not be determined so far.
Methods: This study aimed to analyze the dose-response relationship between cumulative physical workload and hip osteoarthritis by replacing the exposure categories of the included studies with cumulative exposure values of an external reference population. Our meta-regression analysis was based on a recently conducted systematic review (Bergmann A, Bolm-Audorff U, Krone D, Seidler A, Liebers F, Haerting J, Freiberg A, Unverzagt S, Dtsch Arztebl Int 114:581–8, 2017). The main analysis of our meta-regression comprised six case-control studies for men and five for women. The population control subjects of a German multicentre case-control study (Seidler A, Bergmann A, Jäger M, Ellegast R, Ditchen D, Elsner G, Grifka J, Haerting J, Hofmann F, Linhardt O, Luttmann A, Michaelis M, Petereit-Haack G, Schumann B, Bolm-Audorff U, BMC Musculoskelet Disord 10:48, 2009) served as the reference population. Based on the sex-specific cumulative exposure percentiles of the reference population, we assigned exposure values to each category of the included studies using three different cumulative exposure parameters. To estimate the doubling dose (the amount of physical workload to double the risk of hip osteoarthritis) on the basis of all available case-control-studies, meta-regression analyses were conducted based on the linear association between exposure values of the reference population and the logarithm of reported odds ratios (ORs) from the included studies.
Results: In men, the risk to develop hip osteoarthritis was increased by an OR of 1.98 (95% CI 1.20–3.29) per 10,000 tons of weights ≥20 kg handled, 2.08 (95% CI 1.22–3.53) per 10,000 tons handled > 10 times per day and 8.64 (95% CI 1.87–39.91) per 106 operations. These estimations result in doubling dosages of 10,100 tons of weights ≥20 kg handled, 9500 tons ≥20 kg handled > 10 times per day and 321,400 operations of weights ≥20 kg. There was no linear association between manual handling of weights at work and risk to develop hip osteoarthritis in women.
Conclusions: Under specific conditions, the application of an external reference population allows for the derivation of a dose-response relationship despite high exposure heterogeneities in the pooled studies.

Source: Seidler, A., Lüben, L., Hegewald, J., Bolm-Audorff, U., Bergmann, A., Liebers, F., ... et Unverzagt, S. (2018). BMC musculoskeletal disorders, 19(1).

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