EFFECTS OF PASSIVE STATIC STRETCHING ON MECHANICAL, NEUROMUSCULAR, AND CARDIOVASCULAR FUNCTION

Passive static stretching (PSS) induces neuromuscular and vascular adaptations through both mechanical and neural mechanisms, influencing range of motion, muscle strength, and vascular health. While previous research has primarily focused on individual muscles or muscle chains, the regional (compartmental) and systemic effects of PSS remain unclear. This dissertation investigates these adaptations at different levels of analysis. The first two studies examine intermuscular and intramuscular differences in the response of the triceps surae muscles to PSS. Due to a greater loss of stiffness following stretching, the gastrocnemius experiences more pronounced changes in force transmission compared to the soleus. Additionally, passive stretching alters the spatial activation of the gastrocnemius in a heterogeneous manner, likely influenced by central nervous mechanisms, as similar patterns are observed in the contralateral, non-stretched limb. These findings suggest that neuromuscular adaptations to stretching extend beyond local mechanical effects. The third study explores the interplay between neural and mechanical factors in modifying muscle and vascular tissue properties. Given the anatomical proximity of these structures, a correlation between the reduction in arterial and joint stiffness following stretching was expected. However, the absence of correlations between these variables suggests that different mechanisms contribute to the reduction in stiffness observed in both tissues after stretching. The final study investigates the chronic effects of a lower-limb PSS training program on systemic cardiovascular health in hypertensive individuals. While full-body stretching routines have demonstrated antihypertensive benefits, it remains uncertain whether stretching a limited number of muscles can achieve similar results. Findings indicate that localized stretching significantly improves cardiovascular health, suggesting its potential as a non-pharmacological intervention for populations with limited exercise tolerance. In conclusion, this dissertation highlights the differential effects of PSS on synergistic muscles, its role in modulating neuromuscular activation patterns, and its contribution to vascular adaptations. These findings provide new insights into the physiological mechanisms of stretching and support its application in both athletic and clinical settings.