How does static stretching influence the tendons mechanical response?

Tendons respond mechanically to stretching. Prior research has shown that static stretching influences force relaxation. However, no prior work had resolved how specific stretching durations or percentages affect tendon rupture parameters. This gap motivated researchers to test mechanical responses in controlled in vitro settings. Established knowledge includes the role of collagen fibers in tendon elasticity. Yet, the exact impact of stretching duration and deformation remains unclear. This study addresses the need for precise mechanical data on tendon behavior. The focus is on how stretching protocols alter force relaxation and tensile strength. The knowledge gap centers on optimal stretching parameters for clinical use.

The aim was to determine how static stretching affects tendon mechanical properties. Specifically, the study tested stretching intervals of 15, 30, and 45 seconds. It also examined deformation percentages of 2.5% and 3.5%. The motivation was to identify optimal stretching parameters for clinical protocols. The researchers sought to measure force relaxation and tensile strength. They aimed to compare stretched and control groups. The study focused on whether stretching duration or percentage influenced rupture parameters. The goal was to provide evidence for stretching recommendations in orthopedic settings.

The study used bovine calcaneus tendons in an in vitro setup. Six groups of ten tendons each were formed. Groups varied by stretching interval (15, 30, 45 s) and deformation percentage (2.5%, 3.5%). A control group received no stretching. Force relaxation was measured after stretching tests. Stress rupture tests followed to assess tensile strength. Data collection included force relaxation values and rupture parameters. Statistical analysis focused on differences between groups. The study design allowed comparison of stretching effects across intervals and percentages.

Force relaxation stabilized after the 30th second at both deformation levels. The highest force relaxation occurred at 3.5% deformation (p<0.0001). Tensile strength was lowest in the 3.5% group (p=0.0123). No differences in rupture parameters were found between stretched and control groups. Stretch duration and percentage did not interact significantly. The 30-second interval showed the most effective force relaxation. These results suggest optimal stretching time for tendon preparation. The findings highlight the importance of deformation percentage in mechanical response.

The authors reported that force relaxation stabilized after 30 seconds. The highest deformation percentage led to greater force relaxation. Tensile strength was reduced at 3.5% deformation. No differences in rupture parameters were observed between stretched and control groups. The study found no interaction between duration and percentage. The 30-second interval appears most effective for tendon stretching. These findings may inform clinical stretching protocols. The authors suggest considering these results when designing stretching interventions.