Fourteen operators were examined while using the alternative devices. Significant differences were found between the devices in terms of sensory and motor activities, local muscular strain, transgressions of tolerance limits for 4-hour work sessions, and increases in heart rate. Suggestions for redesigning the control center are given, using anthropometric analysis. The relations between the suboptimal design of a work system and the resulting strain is also shown. Five references, figures, and photographs are included. (Author abstract modified)