Acute changes in passive stiffness and range of motion post-stretching

Area of Science:

• Biomechanics
• Sports Science
• Kinesiology

Background:

• Understanding the acute effects of stretching on muscle properties is crucial for optimizing athletic performance and injury prevention.
• Passive hamstring stretching is a common intervention, but its immediate impact on passive stiffness and range of motion (ROM) requires further clarification.

Purpose of the Study:

• To examine changes in passive hamstring stiffness and knee joint range of motion (ROM) after a single bout of stretching.
• To compare stretching with and without subsequent active movement post-stretch.

Main Methods:

• Nine participants underwent testing using a Kincom dynamometer to measure knee joint ROM and passive stiffness.
• Three conditions were tested: passive stretching only, passive stretching with active movement, and a control condition.

Main Results:

• Both stretching conditions led to a 4-5° increase in knee joint ROM compared to the control, though this effect diminished within 5 minutes.
• A small decrease in passive hamstring stiffness was observed post-stretch, likely persisting for at least 20 minutes.

Conclusions:

• A single bout of passive hamstring stretching results in transient improvements in ROM and stiffness.
• These findings suggest that current warm-up protocols incorporating isolated stretching may have limited short-term benefits.