Self-reported work-related musculoskeletal injuries and isometric handgrip strength

Pre-placement examinations for newly recruited health care support staff

Objective

While musculoskeletal disorders (MSD) and physical strength have been extensively studied in health care professionals, little attention has been paid to health care support staff, such as patient care assistants and operation patient assistants, whose jobs are physically demanding. The purpose of this paper was to examine the musculoskeletal symptoms and physical strength of newly recruited health care support staff.

Method

Convenience sampling was conducted on 111 newly employed health care support staff in a public hospital. A custom-made pre-placement examination was performed. Data were analysed using descriptive, correlation, and regression analyses.

Results

Nearly one-third (32%) of the newly recruited health care support staff had experienced musculoskeletal symptoms in at least one body part during the preceding 12 months. Two-thirds (68%) of subjects were physically inactive, and sixty percent was overweight or obese. Handgrip strength was weaker than the local norm. The subjects’ dominant handgrip strength, bilateral lifting, pushing, and pulling force were significantly correlated. Only bilateral lifting was significantly associated with MSD among the newly recruited health care workers.

Conclusions

This study reports the baseline prevalence of MSD symptoms in the newly recruited health care support staff. Their sedentary lifestyle and suboptimal physical strength may render them susceptible to occupational injuries and disease. An effective occupational health programme that provides periodic health surveillance should be considered for high-risk health care workers to allow proper interventions in a timely manner.

Normative reference values of the handgrip strength for the Portuguese workers

Introduction

The active workforce is increasingly aging. However workload, as well as working time and intensity, sometimes remains unchanged. This can be an even more critical situation in older people, since occupational exposure associated with aging, will further reduce the muscle's ability to generate energy, which in turn facilitates the development of these age-related syndromes. This study aims to identify the normative values of handgrip strength for Portuguese workers in the automotive industry.

Methods

About 1225 employees were invited to participate in the study. The final sample consisted of 656 employees in the assembly area. The handgrip strength was measured in kilograms (kg) using the Jamar digital dynamometer. Sex-specific profiles of handgrip strength were designed by the Ordinary Least Square regression (OLS) analysis, where height, age, age squared, and height squared are entered into the models as determining factors of the maximum grip strength in both female and male groups.

Results

The peak mean values of handgrip strength in the group of women was 34 kg in the age group of 35–39 years, and in the group of men the peak mean was 52 kg in the age group of 25–34 years. The most pronounced decline in the female group appears in the age of 30–34 years of about 4 kg and the male group the decline occurs at 2kg below the peak force, in the age group of 40–57 year-olds. This study used a cut-off at 2 SD below by the sex-specific peak mean.

Conclusion

Normative values can help delineate the career path of workers because they portray risk values according to age, height, and gender. The normative values assist health and engineering professionals and ergonomists in adjusting task demands to the morphological and strength characteristics of the workers.

Prediction model of the effect of postural interactions on muscular activity and perceived exertion

Musculoskeletal disorders are a prevalent disease in many Western countries. While a large number of ergonomic analyses and assessment methods are nowadays available, most current methods that assess exposure calculate overall risk scores of individual body segments without considering interaction effects of exposure variables. Therefore, a study was conducted that aimed at investigating and quantifying interaction effects of trunk inclination and arm lifting on ratings of perceived exertion (RPE) and muscle activity. A multiple regression model to predict musculoskeletal load under consideration of interaction effects was derived. The study revealed that there is a significant interaction effect of trunk inclination and arm lifting. Furthermore, final regression models explained variance in exposure variables in a range of R² = 0.68 to R² = 0.147 with a subset of two to three inputs. The predicative equations support the computer-based post-processing of sensor data. Practitioner summary: This article elaborates on the importance of interaction effects of working postures on assessment results of load. In practise, easy to-use-methods for an assessment of working postures are needed. Therefore, a regression model is derived, which facilitates the quantification of work load under consideration of interaction effects. The use of this regression model for the assessment of posture data gathered by range sensors is recommended. Abbreviations: RPE: rating of perceived exertion; MSD: musculoskeletal disorder; OWAS: ovako working posture analysing system; RULA: rapid upper limb assessment; LUBA: postural loading on the upper body assessment; REBA: rapid entire body assessment; OCRA: occupational repetitive action;S D: standard deviation; EMG: surface electromyography; LUT: left upper trapezius pars descendens; RUT: right upper trapezius pars descendens; LLT: left trapezius pars ascendens; RLT: right trapezius pars ascendens; LAD: left anterior deltoideus; RAD: right anterior deltoideus; LES: left erector spinae longissimus; RES: right erector spinae longissimus; SENIAM: surface electroMyoGraphy for the non-invasive assessment of muscles; MVC: maximum voluntary contraction; MANOVA: multivariate analysis of variance; ANOVA: analysis of variance; OLS: ordinary least squares; MANCOVA: multivariate analysis of covariance.

Predicted endurance times during overhead work: influences of duty cycle and tool mass estimated using perceived discomfort

A need for overhead work remains in several industries and such work is an important risk factor for shoulder musculoskeletal problems. In this study, we evaluated the effects of duty cycle and tool mass on endurance times during overhead work. A psychophysical approach was used, via a new methodology that was implemented to more efficiently estimate endurance times (rather than through direct measurements). Participants performed a simulated overhead task in specified combinations of tool mass and duty cycle. Both duty cycle and tool mass have substantial effects on the development of fatigue and estimated endurance times, though the former was more substantial and an interactive effect was evident. Gender differences were not substantial, except when using the largest tool mass. We recommend that, for two-hour periods of overhead work, tool masses greater than 1.25 kg should be avoided, as should duty cycles greater than 50%. Practitioner Summary: The current results may facilitate enhanced design and evaluation of overhead work tasks. In addition, the new estimation approach that was employed may enhance the efficiency of future studies using a psychophysical approach (ie using extrapolation of patterns of reported discomfort to predict longer term outcomes).