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.

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.

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.

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.

Chantiers de construction

Prévention des risques, logistique et avantage économique
Cette brochure est destinée aux différents acteurs d'un projet de construction, notamment aux maîtres d'oeuvre, aux coordonnateurs SPS et aux maîtres d'ouvrage. Ces différents acteurs ont pour obligation de prendre en compte la sécurité et la protection de la santé des travailleurs lors de la conception et de la réalisation des ouvrages. Mais on constate que les aspects économiques des conditions de travail sont généralement peu pris en compte par les donneurs d'ordre, et, lorsqu'ils sont abordés, c'est souvent à travers des idées reçues : l'amélioration des conditions de travail coûterait cher et ses retombées seraient difficilement chiffrables. Cette brochure vise à montrer qu'au contraire la mise en oeuvre d'une organisation logistique contribue à prévenir les accidents du travail et les pathologies liées aux manutentions manuelles tout en améliorant le bilan économique d'une opération.


Multisite musculoskeletal pain predicts medically certified disability retirement among Finns

BACKGROUND: Musculoskeletal pain at several sites (multisite pain) is more common than single-site pain. Little is known on its effects on disability pension (DP) retirement. METHODS: A nationally representative sample comprised 4071 Finns in the workforce aged 30 to 63. Data (questionnaire, interview, clinical examination) were gathered in 2000-2001 and linked with national DP registers for 2000-2011. Pain during the preceding month in 18 locations was combined into four sites (neck, upper limbs, low back, lower limbs). Hazard ratios (HR) of DP were estimated by Cox regression. RESULTS: The HR of any DP (n = 477) was 1.6 (95% confidence interval 1.2-2.1) for one, 2.5 (1.9-3.3) for two, 3.1 (2.3-4.3) for three and 5.6 (4.0-7.8) for four pain sites, when adjusted for age and gender. When additionally adjusted for clinically assessed chronic diseases, the HRs varied from 1.4 (1.0-1.8) to 3.5 (2.5-4.9), respectively. When further adjusted for physical and psychosocial workload, education, body mass index, smoking, exercise and sleep disorders, the HRs were 1.3 (0.9-1.7), 1.6 (1.2-2.2), 1.8 (1.3-2.5) and 2.5 (1.8-3.6). The number of pain sites was especially strong in predicting DPs due to musculoskeletal diseases (HRs in the full model; 3.1 to 4.3), but it also predicted DPs due to other somatic diseases (respective HRs 1.3 to 2.3); pain in all four sites was also predictive of DPs due to mental disorders (full model HR 2.2). CONCLUSIONS: The number of pain sites independently predicted DP retirement. Employees with multisite pain may need specific support to maintain their work ability.

Source: Haukka E, Kaila-Kangas L, Ojajarvi A, et al. European Journal of Pain, 2014.

Prevalence of work-related musculoskeletal symptoms of the neck and upper extremity among dentists in China

OBJECTIVES: Studies from western countries show that dentists are vulnerable to work-related musculoskeletal disorders (WMSDs) of the neck and upper extremities, but little is known about their epidemiology among members of this rapidly growing profession in China. This study aims to investigate the prevalence of WMSDs and identify potential risk factors associated with their occurrence in the dental profession in China.
SETTING AND PARTICIPANTS: A cross-sectional survey was carried out in 52 different hospitals in a large metropolitan city in China. A total of 304 questionnaires were distributed to respondents identified via stratified random sampling and 272 dentists (121 females and 151 males) completed the survey. The response rate was 89.5%.
OUTCOMES: Visual analogue score was used to record neck and upper limb musculoskeletal symptoms on a body chart. Work-related risk factors, including physical and psychosocial factors, were accounted for in the regression analysis.
RESULTS: 88% of the dentists reported at least one musculoskeletal disorder and 83.8% suffered from neck pain. In the multivariate analyses, working hours per day were associated with neck pain (OR=1.43; 95% CI 1.03 to 1.98). Inability to select the appropriate size of dental instrument was associated with shoulder (OR=2.07; 95% CI 1.00 to 4.32) and wrist/hand (OR=2.47; 95% CI 1.15 to 5.32) pain. As for psychosocial factors, high job demand was associated with symptoms in the shoulder (OR=1.09; 95% CI 1.00 to 1.18), elbow (OR=1.11; 95% CI 1.03 to 1.19) and wrist/hand (OR=1.09; 95% CI 1.02 to 1.17). Regular physical exercise was associated with decreased neck pain (OR=0.37; 95% CI 0.14 to 1.00).
CONCLUSIONS: The prevalence of WMSDs among Chinese dentists is high. Specifically, long working hours, inability to select the appropriate size of dental instrument and high job demand are the most significant risk factors.

Source: Beibei Feng, Qi Liang, Yuling Wang, Lars L Andersen, Grace Szeto. BMJ, 2014; 4 (12).

Validation of the HSE manual handling assessment charts as predictors of work-related low back pain

The aim of this research was to ascertain whether HSE's ‘Manual handling Assessment Charts' (MAC tool) could be used to predict workers losing time from work due to low back pain (LBP). Results from the study suggest that as the ‘Hand distance from the lower back' increased, the risk of lost time due to LBP increased. For each 10 cm increase, the rate of lost time increased by approximately 20%. No evidence of relationships between other risk factors in the MAC and lost time was found. There was no evidence that the rate of lost time due to LBP increased with either increasing total MAC lifting score or total MAC carrying score.
Due to imprecision in the model estimates (wide confidence intervals), the lack of statistically significant results, and the limitations of the data, it was decided that it would not be appropriate to alter the scoring system currently used in the MAC based on these data. Duty holders should be confident in carrying on using the MAC tool as the risk factors for LBP included were identified as important by earlier studies.


Evaluation of the use of the pushing and pulling operations risk assessment tool by dutyholders

This report describes the usability testing of a prototype tool for assessing the manual handling risks associated with tasks involving pushing or pulling of loads. It builds on earlier work by HSL to develop Pushing and Pulling Operations Assessment Charts (PPAC) (Research Report 998). Feedback on the assessment of typical operations in the field indicated that the risk factors included in the tool are relevant, useful, relatively easy to identify and that they covered most of the conditions found in workplaces.
Duty holders who took part in the study were able to differentiate between categories of risk for most of the factors, they were also able to argue and justify their choices. The findings indicate that the tool is sufficiently usable and reliable, and it is useful for increasing duty holder confidence in assessing pushing and pulling operations.


Conditions préalables à l’implantation de la rotation chez une population d’assembleurs-monteurs du secteur de l’aéronautique

L'impact des exigences de qualité sur le développement de la polyvalence et sur l'apprentissage
Une grande entreprise du secteur de l'aéronautique désire développer la polyvalence de ses assembleurs-monteurs par l'instauration de la rotation de postes. Convenant qu'il s'agit d'une problématique complexe, l'expertise de l'Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST) est sollicitée. La demande formulée consiste à identifier les conditions requises pour implanter la rotation des postes, souhaitant ainsi prévenir les TMS qui affectent cette population de travailleurs. Le département où sont assemblés les cabines de pilotage de deux des avions-phares de l'entreprise est ciblé à la fois de par les exigences physiques qui le caractérisent, sa position stratégique dans le cycle de production optimisée (lean production) et le haut niveau d'expertise requis pour y effectuer les tâches d'assemblage. On y retrouve quatre stations d'assemblage dans lesquelles se répartissent plus d'une vingtaine d'assembleurs sous la supervision de trois chefs d'équipe. Le travail se caractérise entre autres par des cycles longs – puisque l'assemblage complet d'une cabine s'échelonne sur plusieurs jours – et par des exigences élevées de qualité.


Are elderly construction workers sufficiently fit for heavy manual labour?

This study analysed the work ability of elderly construction workers. Forty male construction workers, 20 young (age < 33 yrs) and 20 senior (age>44 yrs) workers, were tested regarding aerobic power (VO2max) and muscle strength. The aerobic demand of a number of tasks in construction work was measured and compared with the workers' aerobic power. VO2max was higher for the young, and they performed better on most muscle strength tests. The measurements showed that about half of the senior workers had to use more than 30% of their maximum oxygen uptake on some tasks. In conclusion, because elderly construction workers decline in physical fitness, they are more exposed to overload when performing heavy manual work than are their younger peers. Increasing their individual fitness or adjusting their workload may be important for staying in the workforce for such workers.

Source: Jebens E, Mamen A, Medbø JI, Knudsen O, Veiersted KB. Ergonomics, 2014.

L’analyse ergonomique du travail et de la formation

Quelques contributions récentes
Ce numéro spécial est dédié aux travaux récents des membres du groupe Ergonomics analysis of work and training (EAWT) qui se réunit périodiquement, depuis 1991, dans le cadre du Congrès de l'Association internationale d'ergonomie (IEA). Les six contributions présentées ici découlent du dernier congrès tenu à Recife en 2012 et des collaborations subséquentes entre des chercheurs de plusieurs pays. Vous pourrez découvrir les particularités de l'approche ergonomique des questions de formation ainsi que la diversité de ses apports. Ces travaux offrent l'occasion de réfléchir aux conceptions de la formation et à leurs liens avec l'activité de travail et avec les conditions de travail et d'apprentissage. Ils permettent aussi de prendre connaissance des cadres conceptuels et méthodologiques variés qui alimentent aujourd'hui ce domaine de recherche.

Source: Pistes, 2014, vol. 16, no 4.

Effect of a multidisciplinary program for the prevention of low back pain in hospital employees

A randomized controlled trial
BACKGROUND: Hospital workers with physically demanding jobs are at risk for developing recurrent LBP. There is a lack of studies evaluating multidisciplinary prevention of low back pain (LBP) in hospital workers.
OBJECTIVE: This randomized controlled trial evaluates the effect of a multidisciplinary prevention program, focusing on a client-centred approach, on hospital workers at risk for developing LBP.
METHODS: Caregiving hospital workers were allocated to an experimental (12-week lasting multidisciplinary prevention program) or control group (no intervention). They were evaluated prior to the intervention and after a 6 months follow-up period. Primary outcome measures included incidence of LBP, work absenteeism and general health. Secondary outcomes included daily physical activity, job satisfaction and coping strategies.
RESULTS: A significant improvement was seen for passive coping after 6 months follow-up, but no significant differences were observed between groups in primary or other secondary outcome measures (p> 0.05).
CONCLUSIONS: A multidisciplinary prevention program fitting into a bio-psychosocial context may not have been intensive enough to promote a change in daily habitudes, and had no effect on work absenteeism, incidence of LBP or general health. Further research should determine whether prevention of LBP is possible in caregiving personnel.

Source: Roussel, Nathalie, Kos, Daphne, Demeure, Isaline, Heyman, Annette, De Clerck, Marleen, Zinzen, Evert, Struyf, Filip, Nijs, Jo. (2014). Journal of Back and Musculoskeletal Rehabilitation.

Evaluating the effect of four different pointing device designs on upper extremity posture and muscle activity during mousing tasks

The goal of this study was to evaluate the effect of different types of computer pointing devices and placements on posture and muscle activity of the hand and arm. A repeated measures laboratory study with 12 adults (6 females, 6 males) was conducted. Participants completed two mouse-intensive tasks while using a conventional mouse, a trackball, a stand-alone touchpad, and a rollermouse. A motion analysis system and an electromyography system monitored right upper extremity postures and muscle activity, respectively. The rollermouse condition was associated with a more neutral hand posture (lower inter-fingertip spread and greater finger flexion) along with significantly lower forearm extensor muscle activity. The touchpad and rollermouse, which were centrally located, were associated with significantly more neutral shoulder postures, reduced ulnar deviation, and lower forearm extensor muscle activities than other types of pointing devices. Users reported the most difficulty using the trackball and touchpad. Rollermouse was not more difficult to use than any other devices. These results show that computer pointing device design and location elicit significantly different postures and forearm muscle activities during use, especially for the hand posture metrics.

Source: Lin, Michael Y.C., Young, Justin G., & Dennerlein, Jack T. (2015). Applied Ergonomics, 47, 259-264.

Rouler et manutentionner en sécurité

Les poids lourds sont rarement équipés de série d'outils et d'équipements permettant de réduire la pénibilité du travail du conducteur. Ces équipements optionnels sont mal connus des acheteurs de nouveaux véhicules alors qu'ils présentent un réel bénéfice pour le conducteur lors de la conduite, lors des manoeuvres, et lors de la manutention des charges. Cette brochure a pour objectif de présenter les équipements et les outils participant à la réduction de la pénibilité du travail des conducteurs routiers de poids lourds de plus de 3,5 tonnes, et leurs avantages dans la réduction des accidents du travail et maladies professionnelles dont ils sont victimes. L'ensemble des équipements présentés peuvent être acquis à la commande du véhicule ou installés en 2e monte.


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