BALANCE ABILITIES OF WORKERS IN PHYSICALLY DEMANDING JOBS: WITH SPECIAL REFERENCE TO FIREFIGHTERS OF DIFFERENT AGES^*

^*Doctoral dissertation presented on the 5^th November 2004 at the Large Lecture Hall of the Haartman Institute, Helsinki, Finland by permission of Faculty of Medicine of the University of Kuopio, Finland.

The objectives of the present study were to investigate the associations between balance abilities and age, occupation and the use of fire-protective equipment (FPE) in different visual conditions, and the associations of slip and fall risk with balance abilities among workers in physically demanding jobs, especially among workers in fire and rescue work. The reliability and predictive values of balance tests in respect to perceived work ability were also studied. The professional firefighters aged 30 to 56-years (n = 29-135), construction workers (n = 52), home care workers (n = 66) and nursing workers (n = 51) aged 23 to 61 years participated in this study. The data were obtained with balance tests with the use of a force platform, functional balance tests, slipping tests and questionnaires. In one study the balance tests were carried out with and without FPE. The slipping tests with FPE were carried out on a straight 8-m long path that had one area covered by water and detergent or glycerol. Perceived work ability at baseline and after a 3-year follow-up was determined with the use of the work ability index (WAI). In the reliability study, the dynamic balance tests were repeated six times in two testing periods at an interval of 2 months. The results indicated that the balance abilities of firefighters over 49 years of age were significantly poorer than those of firefighters in the age groups of <40 and 40-49 years. The decline of balance abilities among construction, home care and nursing workers was not as consistent. Postural balance was also more harmfully affected among the older firefighters (43-56 years) than among the younger ones (33-38 years) by the use of FPE without visual input. Self-contained breathing apparatus was the most significant single piece of FPE to impair balance in both groups. Furthermore, fast and controlled performance in the dynamic stability test based on visual feedback was related to smaller slip and fall risk with FPE in both age groups. The older firefighters tended to have longer and more serious slips than the younger ones. In addition, the construction workers were significantly faster and made fewer errors than the firefighters in the functional balance test. Among the firefighters, poor performance on the balance tests significantly predicted a reduced WAI after a follow-up of 3 years. The dynamic stability and functional balance tests showed reasonable reliability, especially when the reliability was estimated from the best of at least three repeated trials. The present results suggest that balance abilities should be taken into account in follow-ups of the work ability of firefighters, as well as in the organization of work tasks and the development of the characteristics of FPE. It is also essential to provide ample balance training opportunities for firefighters with and without FPE. The balance assessments of the present study can be included when prerequisites of work ability are evaluated and followed-up for firefighters.

KEY WORDS: Musculoskeletal equilibrium, posture, aging, occupations, rescue work, protective devices, risk factors, occupational exposure, comparative study, cross-sectional studies, follow-up studies, reproducibility of results.