Cumulative trauma disorders are caused, aggrevated and precipatitated by repetitive exertions and movements workers are routinely required to perform, and awkward postures they must assume. Currently there are no quantitative standards available for protecting workers from excessive exposure to these hazards. But before dose-reponse relationships can be established leading to exposure standards for preventing these disorders, practical methods are needed for measuring and characterizing worker exposure to cumulative trauma stress factors. This project will develop efficient analytical techniques for assessing physical stress strain associated with hand-intensive tasks containing repetitive motion and forceful exertions. A practical instrumentation system will be implemented for continuously measuring wrist posture and hand force. Use of spectral analysis will be investigated characterizing task repetitiveness, forcefulness, and postural stress. Data will be transformed into the frequency domain for determining the frequency and magnitude of repetitive motion and forceful exertions performed during manual work. Psychophysical measures of localized fatigue and discomfort will be correlated with posture and force spectral components for designing digital filters for frequency-weighted physical stress measurements for controlling strain associated with repetitive tasks. Finally capability for characterizing and reducing stress and strain associated with repetitive motion exertions will be tested using both industrial tasks simulated in the laboratory and actual tasks performed in the workplace.
