Long-term effects of static stretching on the musculotendinous stiffness in older adults: a systematic review and meta-analysis

Long-term static stretching is commonly employed in elderly rehabilitation to enhance range of motion (RoM), which is crucial for fall prevention and improving gait parameters. A RoM increase can result from enhanced stretch tolerance and/or musculotendinous (MTU) adaptations. Previous studies have also shown muscle hypertrophy following long-term stretching protocols in deconditioned populations. Mechanisms underlying RoM increase due to stretching in the elderly are scarce. This review aims to provide an overview of the long-term effects of static stretching on the structure and mechanical properties of the MTU in older adults.

Systematic searches were performed on three databases (PubMed, Epistemonikos, and Scopus), and cross-referencing, according to the PICO method. Meta-analyses were conducted to examine the impact of long-term stretching on range of motion, maximally tolerated resistance, and MTU stiffness.

Meta-analysis in older adults unveil that long-term static stretching increases the passive stiffness of the MTU (effect size = 0.61; 95% confidence interval = [0.10 1.12], p = 0.02, I² = 0), increases maximal tolerated resistance (effect size = 0.70; 95% confidence interval = [0.27 1.14], p < 0.01, I² = 0) and increases RoM (effect size = 0.67; 95% confidence interval = [0.24 1.11], p < 0.01, I² = 0).

Improvement of flexibility among elderly individuals following long-term passive stretching procedures is due to enhanced stretch tolerance and MTU modification. It underscores the critical role of stretching in both restoring functional mobility and muscle retraining. More studies are needed to establish stronger evidence.