Gravitational demand on the neck musculature during tablet computer use

Tablet computer use requires substantial head and neck flexion, which is a risk factor for neck pain. The goal of this study was to evaluate the biomechanics of the head–neck system during seated tablet computer use under a variety of conditions. A physiologically relevant variable, gravitational demand (the ratio of gravitational moment due to the weight of the head to maximal muscle moment capacity), was estimated using a musculoskeletal model incorporating subject-specific size and intervertebral postures from radiographs. Gravitational demand in postures adopted during tablet computer use was 3–5 times that of the neutral posture, with the lowest demand when the tablet was in a high propped position. Moreover, the estimated gravitational demand could be correlated to head and neck postural measures (0.48 < R2 < 0.64, p < 0.001). These findings provide quantitative data about mechanical requirements on the neck musculature during tablet computer use and are important for developing ergonomics guidelines.

Source: Anita N. Vasavada, Derek D. Nevins, Steven M. Monda, Ellis Hughes & David C. Lin. Ergonomics, 2015.
http://dx.doi.org/10.1080/00140139.2015.1005166

Effect of firefighters' personal protective equipment on gait

The biomechanical experiment with eight male and four female firefighters demonstrates that the effect of adding essential equipment: turnout ensemble, self-contained breathing apparatus, and boots (leather and rubber boots), significantly restricts foot pronation. This finding is supported by a decrease in anterior-posterior and medial-lateral excursion of center of plantar pressure (COP) trajectory during walking. The accumulation of this equipment decreases COP velocity and increases foot-ground contact time and stride time, indicating increased gait instability. An increase in the flexing resistance of the boots is the major contributor to restricted foot pronation and gait instability as evidenced by the greater decrease in excursion of COP in leather boots (greater flexing resistance) than in rubber boots (lower resistance). The leather boots also shows the greatest increase in foot contact time and stride time. These negative impacts can increase musculoskeletal injuries in unfavorable fire ground environments.

Source: Park H, Kim S, Morris K, Moukperian M, Moon Y, Stull. J. Appl. Ergon, 2015; 48: 42-48.
http://dx.doi.org/10.1016/j.apergo.2014.11.001

A Tailored Workplace Exercise Program for Women at Risk for Neck and Upper Limb Musculoskeletal Disorders

A Randomized Controlled Trial
Objective: The aim of this study was to evaluate a tailored physical activity protocol performed in a work environment with a group of female workers employed in manual precision tasks to reduce upper limb pain.
Methods: Sixty female subjects were randomly assigned to an intervention group or a control group. The IG was administered of a 6-month, twice-a-week, tailored exercise program, whereas the CG received no intervention.
Results: The IG showed a reduction on shoulder pain accompanied by increases on the range of motion measures. In addition, reductions in upper limb pain and neck disability were detected with concomitant increases in grip strength.
Conclusions: This study indicated positive effects of a tailored workplace exercise protocol in female workers exposed to moderate risk for work-related musculoskeletal disorders, showing clinically meaningful reductions of pain symptoms and disability on upper limb and neck regions.

Source: Rasotto, Chiara; Bergamin, Marco; Sieverdes, John C.; Gobbo, Stefano; Alberton, Cristine L.; Neunhaeuserer, Daniel; Maso, Stefano; Zaccaria, Marco; Ermolao, Andrea. Journal of Occupational & Environmental Medicine: February 2015, Volume 57, Issue 2, p. 178–183.
http://dx.doi.org/10.1097/JOM.0000000000000329

Association between objectively measured sitting time and neck–shoulder pain among blue-collar workers

OBJECTIVES: Prolonged sitting has been suggested as a risk factor for neck-shoulder pain (NSP). Using a cross-sectional design, we investigated the extent to which objectively measured time sitting is associated with NSP among blue-collar workers. METHODS: Sitting time was measured during multiple working days on male (n = 118) and female (n = 84) blue-collar workers (n = 202) using triaxial accelerometers (Actigraph) placed on the thigh and trunk. Workers were categorized into having, on average, a low, moderate or high sitting time, with mean values (SD between subjects) of 4.9 (1.0), 7.3 (0.5) and 9.6 (1.1) h in total per day. Workers rated their largest NSP intensity during the previous month on a numerical scale (0-9) and were subsequently dichotomized into a low and high NSP intensity group (ratings 0-4 and >4, respectively). Logistic regression analyses adjusted for several individual, and work-related factors were used to investigate the association between average sitting time per day (work, leisure and total) and NSP intensity. RESULTS: For total sitting time, workers in the high sitting category were more likely (adjusted OR 2.97, CI 1.25-7.03) to report high NSP intensity than those who sat moderately (reference category). Low sitting during work was associated with a reduced NSP intensity, but only for males (adjusted OR 0.26 CI 0.07-0.96). No significant association was found between sitting during leisure and NSP intensity. CONCLUSION: These findings suggest an association between sitting time, in total per day and specifically during work, and NSP intensity among blue-collar workers. We encourage studying the structure and explanation of this association further in prospective studies on larger populations.

Source: Hallman DM, Gupta N, Mathiassen SE, et al. Association between objectively measured sitting time and neck-shoulder pain among blue-collar workers. International Archives of Occupational and Environmental Health, 2015.
http://dx.doi.org/10.1007/s00420-015-1031-4

La grande distribution - Dossier

Vaste secteur aux emplois variés, la grande distribution représente l'un des premiers employeurs de France. Marquée par une forte sinistralité, elle a bénéficié d'un plan national d'actions concertées déployé par le réseau Assurance maladie-risques professionnels. Les efforts commencent à payer et un grand nombre d'entreprises restent suivies par les Caisses régionales de santé au travail, afin d'amplifier les actions de prévention en cours.

Source: Travail & Sécurité, no 759, mars 2015.
http://www.travail-et-securite.fr/ts/dossier/.html

Les troubles musculo-squelettiques du membre supérieur en France

Ce document de synthèse porte sur les troubles musculo-squelettiques (TMS) du membre supérieur. Dans ce document, le lecteur trouvera des données sur leur fréquence en termes de prévalence et d'incidence, ainsi que sur la fréquence des expositions aux principaux facteurs de risque connus, selon le sexe, l'âge, les catégories professionnelles et les grands secteurs d'activité. Il trouvera également des informations sur la part des TMS des membres supérieurs attribuable au travail, selon les catégories professionnelles et les grands secteurs d'activité et sur l'ampleur de la sous-déclaration au titre des tableaux de maladies professionnelles indemnisables.
Enfin, un certain nombre de questions permettent de mettre en perspective les résultats présentés.

Source: http://www.invs.sante.fr/Publications-et-outils/Rapports-et-syntheses/Travail-et-sante/2015/Des-indicateurs-en-sante-travail

Revised NIOSH Lifting Equation May generate spine loads exceeding recommended limits

The 1991 NIOSH Lifting Equation (NLE) is widely used to assess the risk of injury to spine by providing estimates of the recommended weight limit (RWL) in hands. The present study uses the predictive equations developed based on a detailed trunk musculoskeletal biomechanical model to verify whether the RWL generates L5-S1 loads within the limits (e.g., 3400 N for compression recommended by NIOSH and 1000 N for shear recommended in some studies). Fifty lifting activities are simulated here to evaluate the RWL by the NLE and the L5-S1 loads by the predictive equations. In lifting activities involving moderate to large forward trunk flexion, the estimated RWL generates L5-S1 spine loads exceeding the recommended limits. The NIOSH vertical multiplier is the likely cause of this inadequacy; a revised multiplier accounting for the trunk flexion angle is hence needed. The use of a fixed 3400 N compression limit is also questioned.

Source: Navid Arjmand, Mohammad Amini, Aboulfazl Shirazi-Adl, André Plamondon, Mohammad Parnianpour. International Journal of Industrial Ergonomics, Volume 47, May 2015, p. 1-8.
http://dx.doi.org/10.1016/j.ergon.2014.09.010

Démarche de prévention des troubles musculo-squelettiques (TMS)

Le présent document est un guide méthodologique, fondé sur un recueil de pratiques, à destination des employeurs publics et des acteurs de la prévention. Il vise à accompagner les employeurs publics dans la mise en place d'un dispositif de prévention des troubles musculo-squelettiques efficace et durable.

Source: http://www.fonction-publique.gouv.fr/files/files/publications/coll_outils_de_la_GRH/guide_pratique_TMS.pdf

Ergonomic design of crane cabin interior

The path to improved safety
Many procedures in the development process of crane cabins today are still based on the specific experience of manufacturers and historical guidelines. It is not surprising that they fail to meet the needs of a large proportion of operators. Accordingly, the need for more objective, theoretically justified and consistent models, that will minimize crane operators' biomechanical and visual problems through anthropometric characteristic analysis to improve safety and prevent crane related fatalities and injuries, arises. In that aim we firstly identified the critical characteristics of existing crane cabins linked to visibility and posture (seat and armrest problems) using users' opinions and Pareto analysis. We then collected rarely available data on crane operators in Serbian companies (64 in the first and 10 operators in the control sample) and proposed methodology for the ergonomic assessment of crane cabins based on drawing-board mannequins and kinematic modeling. The implemented methodology interval estimate obtains an interior space of 1095 × 1150 × 1865 mm in which is possible to eliminate the critical characteristics of existing crane cabins. The research results fulfill user needs not satisfied in existing crane cabins and suggest certain changes to existing standards on the path to improved safety.

Source: Spasojevic Brkic VK, Klarin MM, Brkic AD. Safety Sci. 2015; 73: 43-51.
http://dx.doi.org/10.1016/j.ssci.2014.11.010

A Tailored Workplace Exercise Program for Women at Risk for Neck and Upper Limb Musculoskeletal Disorders

A Randomized Controlled Trial
Objective: The aim of this study was to evaluate a tailored physical activity protocol performed in a work environment with a group of female workers employed in manual precision tasks to reduce upper limb pain.
Methods: Sixty female subjects were randomly assigned to an intervention group or a control group. The IG was administered of a 6-month, twice-a-week, tailored exercise program, whereas the CG received no intervention.
Results: The IG showed a reduction on shoulder pain accompanied by increases on the range of motion measures. In addition, reductions in upper limb pain and neck disability were detected with concomitant increases in grip strength.
Conclusions: This study indicated positive effects of a tailored workplace exercise protocol in female workers exposed to moderate risk for work-related musculoskeletal disorders, showing clinically meaningful reductions of pain symptoms and disability on upper limb and neck regions.

Source: Rasotto, Chiara; Bergamin, Marco; Sieverdes, John C.; Gobbo, Stefano; Alberton, Cristine L.; Neunhaeuserer, Daniel; Maso, Stefano; Zaccaria, Marco; Ermolao, Andrea. Journal of Occupational & Environmental Medicine: February 2015, Volume 57, Issue 2, p. 178–183.
http://dx.doi.org/10.1097/JOM.0000000000000329

Work-related psychosocial risk factors and musculoskeletal disorders in hospital nurses and nursing aides

A systematic review and meta-analysis
Objectives :To estimate the association between psychosocial risk factors in the workplace and musculoskeletal disorders (MSD) in nurses and aides.
Design : Systematic review and meta-analysis.
Data sources : An electronic search was performed using MEDLINE (Pubmed), Psychinfo, Web of Science, Tripdatabase, Cochrane Central Controlled Trials, NIOSHTIC and Joanna Briggs Institute of Systematic Reviews on Nursing and Midwifery, to identify observational studies assessing the role of psychosocial risk factors on MSD in hospital nurses and nursing aides.
Review methods : Two reviewers independently assessed eligibility and extracted data. Quality assessment was conducted independently by two reviewers using an adapted version of the Standardized Quality Scale. Random-effects meta-analysis was performed by subsets based on specific anatomical site and the exposure to specific psychosocial risk factors. Heterogeneity for each subset of meta-analysis was assessed and meta-regressions were conducted to examine the source of heterogeneity among studies.
Results : Twenty-four articles were included in the review, seventeen of which were selected for meta-analysis. An association was identified between high psychosocial demands–low job control with prevalent and incident low back pain (OR 1.56; 95% CI 1.22–1.99 and OR 1.52; 95% CI 1.14–2.01, respectively), prevalent shoulder pain (OR 1.89; 95% CI 1.53–2.34), prevalent knee pain (OR 2.21; 95% CI 1.07–4.54), and prevalent pain at any anatomical site (OR 1.38; 95% CI 1.09–1.75). Effort-reward imbalance was associated with prevalent MSD at any anatomical site (OR 6.13; 95% CI 5.32–7.07) and low social support with incident back pain (OR 1.82; 95% CI 1.43–2.32). Heterogeneity was generally low for most subsets of meta-analysis.
Conclusion : This meta-analysis suggests that psychosocial risk factors at the workplace are associated with MSD in hospital nurses and nursing aides. Although most preventive strategies at the workplace are focused on ergonomic risk factors, improving the psychosocial work environment might have an impact on reducing MSDs.

Source: Bernal, Dinora, Campos-Serna, Javier, Tobias, Aurelio, Vargas-Prada, Sergio, Benavides, Fernando G., Serra, Consol. International Journal of Nursing Studies, 2015, 52(2), 635-648
http://dx.doi.org/10.1016/j.ijnurstu.2014.11.003

Process Evaluation of Workplace Interventions with Physical Exercise to Reduce Musculoskeletal Disorders

Process evaluation is important to explain success or failure of workplace interventions. This study performs a summative process evaluation of workplace interventions with physical exercise. As part of a randomized controlled trial 132 office workers with neck and shoulder pain were to participate in 10 weeks of elastic resistance training five times a week at the workplace; the 2min group performed a single set of lateral raise to failure, and the 12min group performed 5-6 sets with 8–12 repetitions. Participants received a single instructional session together with a training diary and manual at baseline (100% dose delivered and 100% dose received), and 59 and 57 participants, respectively, replied to the process evaluation questionnaire at 10-week follow-up. Results showed that in the 2 and 12min groups, respectively, 82% and 81% of the participants completed more than 30 training sessions. However, two-thirds of the participants would have preferred more than a single exercise to vary between. In the 12 versus 2min group more participants experienced the training sessions as too long (30% versus 5%). Most participants (67–92%) found the training diary and manual helpful, adequacy in a single instructional session, and satisfaction with the type of training. Among those with low adherence, lack of time (51%) and difficulties in starting exercising after illness (26%) were common barriers for regular training. Among those with low adherence, 52% felt that five training sessions per week were too much, and 29% would rather have trained a completely different kind of exercise. In conclusion, resistance training at the workplace is generally well received among office workers with neck-shoulder pain, but a one-size-fits-all approach is not feasible for all employees.

Source: Lars L. Andersen, Mette K. Zebis. Int J Rheumatol, 2014.
http://dx.doi.org/10.1155/2014/761363

Effect of horizontal pick and place locations on shoulder kinematics

In this study the effects of horizontal bin locations in an order picking workstation on upper arm elevation, trunk inclination and hand use were investigated. Eight subjects moved (self-paced) light or heavy products (0.2 and 3.0 kg) from a central product bin to an inner or outer order bin (at 60 or 150 cm) on the left or right side of the workstation, while movements were recorded. The outer compared to inner bin location resulted in more upper arm elevation and trunk inclination per work cycle, both in terms of number of peak values and in terms of time integrals of angles (which is a dose measure over time). Considering the peak values and time integrals per minute (instead of per work cycle), these effects are reduced, due to the higher cycle times for outer bins. Hand use (left, right or both) was not affected by order bin locations.

Source: R. Könemann, T. Bosch, I. Kingma, J.H. Van Dieën & M.P. De Looze. Ergonomics, Volume 58,  Issue 2, 2015.
http://dx.doi.org/10.1080/00140139.2014.968636

Manual handling: differences in perceived effort, success rate and kinematics between three different pushing techniques

This study examined the perceived effort, success rates and kinematics for three push strategies in a simulated lateral patient transfer (horizontal slide). Thirteen healthy subjects (four males) completed three repetition pushing loads of 6, 10 and 14 kg in random order; with a spontaneous push strategy, then with a straight-back bent-knees (squat) strategy and the preparatory pelvic movement (‘rockback') strategy in random order. Perceived effort and kinematic parameters measured at the onset of movement and at maximum push excursion were compared between strategies and between loads with repeated measures ANOVA. The spontaneous and ‘rockback' strategies achieved the pushing task with less perceived effort across all loads than the squat push (P < 0.001). Only 3/13 participants were successful on all attempts at pushing the 14 kg load using a squat strategy, which contrasted with 12/13 participants when the spontaneous strategy or the ‘rockback' strategy was used. Forward movement of the pelvis and forward trunk inclination may be positively associated with lower perceived effort in the push task.

Source: Lynn Varcin, Andrew Claus, Wolbert van den Hoorn & Paul Hodges. Ergonomics, Volume 58,  Issue 2, 2015.
http://dx.doi.org/10.1080/00140139.2014.970586

A frequency–duty cycle equation for the ACGIH hand activity level

A new equation for predicting the hand activity level (HAL) used in the American Conference for Government Industrial Hygienists threshold limit value (TLV) was based on exertion frequency (F) and percentage duty cycle (D). The TLV includes a table for estimating HAL from F and D originating from data in Latko et al. (Latko WA, Armstrong TJ, Foulke JA, Herrin GD, Rabourn RA, Ulin SS, Development and evaluation of an observational method for assessing repetition in hand tasks. American Industrial Hygiene Association Journal, 58(4):278–285, 1997) and post hoc adjustments that include extrapolations outside of the data range. Multimedia video task analysis determined D for two additional jobs from Latko's study not in the original data-set, and a new nonlinear regression equation was developed to better fit the data and create a more accurate table. The equation, HAL = 6.56 ln D[F 1.31/1 + 3.18 F1.31], generally matches the TLV HAL lookup table, and is a substantial improvement over the linear model, particularly for F > 1.25 Hz and D > 60% jobs. The equation more closely fits the data and applies the TLVw using a continuous function.

Source: Robert G. Radwin, David P. Azari, Mary J. Lindstrom, Sheryl S. Ulinc, Thomas J. Armstrong and David Rempel. Ergonomics, 2015, Vol. 58, No. 2, 173–183. http://dx.doi.org/10.1080/00140139.2014.966154

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