Effects of vibration on grip and push force-recall performance

Comprehensive assessments of health risks associated with the operation of vibratory tools should include evaluations of hand–tool coupling forces. The use of hand-force instrumentation in field applications can be difficult and expensive. A previous study (McDowell, T.W., Wiker, S.F., Dong, R.G., Welcome, D.E., Schopper, A.W., 2006. Evaluation of psychometric estimates of vibratory hand–tool grip and push forces. International Journal of Industrial Ergonomics 36(2), 119–128.) examined various combinations of handle vibration frequencies and grip and push force levels upon one's ability to recall those forces using psychophysical methods. The results of that study were promising. The present study is a follow-up experiment that further investigated the potential for using psychophysical force-recall methods to estimate grip and push forces when operating powered hand tools. In this experiment, 20 subjects (10 male, 10 female) grasped and pushed an instrumented handle for 45 s at one of three force levels while it vibrated sinusoidally at one of four frequencies (16, 31.5, 63, or 125 Hz) or with no vibration. Unlike the first study, two levels of vibration magnitude were examined along with gender differences. This study further clarifies relationships between vibration exposure characteristics and their effects on grip and push force-recall performance. Vibration exposure conditions and other influential factors can be accounted for in enhanced force-recall methodologies that can be incorporated into a variety of workplace exposure assessment applications.Relevance to industryWorkers who are repeatedly exposed to intense hand-transmitted vibration are at risk of developing health problems. To better assess these health risks, hand–tool coupling forces should be evaluated. A refined psychophysical force-recall technique may be a practical alternative to expensive or fragile instrumentation. Before such a method is proposed for laboratory or field applications, an understanding of vibration effects upon force-recall performance must first be explored.