Wrist positions and movements as possible risk factors during machine milking

High prevalence of hand and wrist symptoms has been found in females working with machine milking. Therefore the aim of this study was to quantify the positions and movements of the wrist during machine milking, and to compare tethering and loose-housing systems with respect to this. Biaxial electrogoniometers and data loggers were used for recording flexion and deviation angles of both the right and left wrists in 11 healthy milkers. For each individual 25 min of representative work was recorded in each system. High values of dorsiflexion and radial deviation were found, which might induce an increased risk of carpal tunnel syndrome. Moreover, the velocity and repetitiveness were close to those values described in repetitive work with a high risk of elbow and hand disorders in the fish-processing industry and giro-form data entry work. According to our findings, the load on the upper extremities has increased with respect to dorsiflexed hand position and repetitiveness when milking in the modern loose-housing milking system. This is probably due to the change of the working position and/or the higher productivity (number of cows that milked per time unit) in the loose-housing system as compared to the old-fashioned tethering system. These negative effects on wrist positions and movements should be considered when building new milking systems.