Publications

Myoton Clarification Note: A Guide to Interpreting the Inverse Relationship Between Logarithmic Decrement and Tissue Elasticity

Background: Mechanization in olive harvesting has improved productivity but introduced new ergonomic challenges, particularly related to vibration exposure and sustained overhead work. This study investigates the acute and short-term physiological effects of using an electric olive harvester through objective instrumental assessment.

Methods: Ten healthy male volunteers performed a standardized 15-min simulated harvesting task using an electric olive harvester. Muscle tone, stiffness, and elasticity of bilateral deltoid, biceps, and triceps were assessed by myotonometry at baseline (T0), immediately post-task (T1), and after 2 h recovery (T2). Infrared thermography evaluated cervical, dorsal, and lumbar skin temperature at the same timepoints.

Results: Significant, side-dependent alterations in myotonometric parameters were observed, with marked increases in tone and stiffness of dominant upper-limb muscles and asymmetric adaptations between limbs (p < 0.001, large effect sizes). Infrared thermography revealed significant post-task reductions in skin temperature across spinal regions, with a partial return toward baseline within the 2 h observation window (p < 0.01). These findings describe short-term, task-related thermoregulatory responses following sustained work.

Conclusions: Even short-term use of electric olive harvesters induces measurable biomechanical and thermophysiological stress. The integrated use of myotonometry and infrared thermography provides a sensitive, field-adaptable framework for early ergonomic risk detection and prevention of work-related musculoskeletal disorders in agriculture.

Keywords: electric olive harvester, agricultural ergonomics, myotonometry, infrared thermography, musculoskeletal disorders, occupational medicine

This study demonstrates that the use of electric olive harvesters, even for short periods, can induce measurable biomechanical and thermophysiological stress in agricultural workers. Through the combined application of myotonometry and infrared thermography, we detected significant measurable task-related physiological adaptations in muscle stiffness, tone, and elasticity, along with significant reductions in spinal temperature, suggesting localized overload and transient vascular compromise.

The evidence supports the hypothesis that this tool, while reducing overall workload, may introduce specific ergonomic risks. The presence of bilateral asymmetry, partial return toward baseline after use, and regional changes in muscle mechanical behavior reinforce the conclusion that tool-based ergonomic assessment protocols are essential in agriculture. The results of this study may contribute to the implementation of appropriate risk assessments for agricultural workers and support the work of occupational physicians in health surveillance.

From a preventive perspective, these findings highlight the need for integrating ergonomic monitoring into routine occupational health surveillance programs, with the aim of identifying early functional alterations before the onset of clinically manifest musculoskeletal disorder. Furthermore, the use of portable, non-invasive technologies such as myotonometry and IRT can serve not only for early risk detection but also as decision-support tools for designing interventions, improving equipment, and optimizing work-rest cycles. Future research should focus on longitudinal study designs, larger worker populations, and the evaluation of targeted preventive interventions (e.g., ergonomic training, task rotation, and tool redesign) to define evidence-based thresholds for exposure and recovery in agricultural settings.