Working Posture and the Center of Mass Assessment While Starting a Chainsaw: A Case Study among Forestry Workers in Croatia

Abstract

Motor-manual work with a chainsaw is still an irreplaceable occupational activity in forest harvesting operations in Croatia and in many other countries. Chainsaw workers are exposed to different risk factors, such as noise and vibrations, heavy load lifting, awkward and preflexion postures, repetitive movements, etc. The working posture and the assessment of the center of mass plays an important role in understanding the exposure of forest workers to postural and occupational risks, either as a part of the entire work process or as a part of an individual element of the work technique. Therefore, the aim of this research was to investigate the impact of three different chainsaw starting methods (from the ground, between the knees, and “drop starting”) on the postural load of the chainsaw worker and its association with personal and occupational factors. The field portion of data collection was conducted in the second and third quarters of 2022. For trunk posture assessment (n = 74), the rapid entire body assessment (REBA) tool was used, and for the center of mass measurement (n = 28), the Xsens MVN Link motion capture suit was used, a relatively new technology that allows data collection in real field conditions. Descriptive and inferential statistical methods were used to verify and analyze the field data. Based on the obtained results, almost 50% of the sampled chainsaw workers ignored safety instructions and preferred “drop starting” a chainsaw. The results also showed that there is a significant difference between the three starting methods in the REBA score, as well as in the number of segments scored during the assessment. The obtained mean REBA score for all three methods is between 4 and 7, placing all methods at a medium level of MSD risk. Regarding the analysis of the Center of Mass (CoM) vertical deviation, the statistical difference is noticeable for the body mass index (BMI) group, the group related to experience with the chainsaw, and the age and height group in relation to three methods for starting a chainsaw. The safest method, which implies starting a chainsaw from the ground, resulted also as the riskiest in terms of postural strain, which, cumulatively over the time variable, can contribute to health problems in forest workers. In conclusion, related to the future process of professional training development for chainsaw workers, an integral part of the training must contain the most optimal postural-movement habits that need to be defined by further kinematic research in forestry.