Examination of the relationship between trunk control and the viscoelastic properties of trunk muscles in individuals with Parkinson's disease

The aim of this study is to evaluate the relationship between trunk control and the viscoelastic properties of trunk muscles in individuals diagnosed with Parkinson's disease. A total of 38 participants aged between 40 and 70 years with a diagnosis of Parkinson's disease were assessed using the Parkinson's Disease Questionnaire (PDQ-39) for quality of life, the Functional Reach Test (FRT) and the Berg Balance Scale (BBS) for balance, the Hodkinson Mental Test (HMT) for cognitive status, the Hoehn and Yahr Scale (HYS) for disease severity, the MyotonPro device for muscle elasticity, and the Trunk Impairment Scale (TIS) for trunk control. Relationships between continuous variables were analyzed using Pearson or Spearman rank correlation coefficients. The findings demonstrated significant correlations between trunk control and the viscoelastic properties of the muscles. In particular, significant relationships were found between the Trunk Impairment Scale and muscle tone (r = 0.721; p <0.01), stiffness (r = 0.681; p <0.01), and elasticity (r =-0.643; p <0.01). Moreover, parameters such as muscle relaxation time and creep were also found to influence trunk control. The correlations obtained from the Trunk Impairment Scale indicated that higher muscle tone and stiffness levels in trunk muscles were associated with better postural control. For instance, a strong relationship was observed between the tone of the Lumbar Multifidus muscle and trunk control (r = 0.721). These findings suggest that the viscoelastic properties of trunk muscles should be taken into account in physiotherapy interventions aimed at enhancing functional independence in individuals with Parkinson's disease. In conclusion, trunk control depends not only on neural control mechanisms but also on the biomechanical properties of muscles. This study highlights the importance of targeted interventions addressing the viscoelastic properties of muscles in the rehabilitation of patients with Parkinson's disease and provides valuable insights to guide future research.