Acute effects of resetting the stretching intensity on range of motion and passive stiffness in healthy adults: A randomized crossover trial

Abstract

Introduction: Static stretching, a common method used to improve flexibility, has traditionally involved repeated stretching until reaching the initial or pre-determined stretching angle or torque. However, recent recommendations suggest that stretching until reaching a new maximal angle may offer greater benefits owing to increased stretching intensity. This study aimed to examine the acute effects of resetting the static stretching intensity on flexibility.

Methods: In this randomized crossover trial, 14 healthy participants performed 300-s of static stretching of the right hamstrings randomly under two conditions: resetting the stretching intensity at new maximal knee extension angles every 30 s (10 × 30-s) or no-resetting (1 × 300-s). The outcomes assessed included range of motion (ROM), passive torque (PT) at pain onset, passive stiffness before and after stretching, and stretching angle during stretching.

Results: During the 10 × 30-s condition, stretching angle was increased gradually (p < 0.05). Significant improvements were observed in ROM, PT at pain onset, and passive stiffness (p < 0.05) after stretching under both conditions. Moreover, the relative improvement in these parameters was greater under the 10 × 30-s condition than under the 1 × 300-s condition (p < 0.05).

Conclusion: These findings suggest that resetting stretching intensity can enhance flexibility, possibly due to the increased stretching intensity, underscoring the importance of individualized stretching approaches to optimize flexibility outcomes.

Keywords: Intensity of stretching; Passive stiffness; Passive torque; Range of motion; Static stretching.