Acute and prolonged effects of passive stretching with and without vibration on flexibility, muscle–tendon stiffness and leg skin temperature in older adults: an assessor-blinded randomized cross-over trial

Abstract Purpose Stretching is a common strategy to acutely improve range of motion (ROM). Underlying mechanisms typically involve stretch tolerance and reduced tissue stiffness. Alternatively, vibration training can be used to improve ROM which can be attributed to circulatory and neural mechanisms. While combining stretching with vibration yields small benefits in young and healthy adults, evidence in older adults is scarce. The objective was to investigate whether superimposing vibration on stretching provides acute ROM benefits compared to stretching alone on flexibility, muscle–tendon stiffness, and skin temperature. Methods Conducted as assessor-blinded, randomized cross-over study with three conditions, eight participants performed either stretching + vibration (ST + V), stretching alone (ST), and passive control (CG). ROM was evaluated via the passive straight-leg-raise and active sit-and-reach test. Biceps femoris and Achilles tendon stiffness were measured via myotonometry. Skin temperature was captured via infrared thermography. Results Both intervention conditions improved passive ROM by large effect sizes ( d = 2.16–3.16, p < 0.001), but only ST + V enhanced active ROM ( d = 1.23, p = 0.048). Vibration superimposition also significantly moderated viscoelastic parameters and maintained/elevated calf skin temperature, whereas temperature declined in ST and CG by moderate to high effect size. Achilles tendon stiffness decreased immediately after ST ( d = − 1.24, p = 0.049) and 30 min after ST + V ( d = − 1.64, p = 0.015). Conclusion Discussing the tonic vibration reflex as underlying mechanism, this study showed superimposed vibration increased active ROM and decreased stiffness. Although additional vibration could offer additional practical benefits for flexibility interventions in aging populations, the clinical relevance must be further investigated in larger populations. Trial Registration : This clinical trial was retrospectively registered at www.drks.de (ID: DRKS00037552, date: 31.07.2025).