Static stretching time required to reduce iliacus muscle stiffness

Area of Science:

• Biomechanics
• Musculoskeletal Physiology

Background:

• Static stretching (SS) is recognized for reducing muscle stiffness.
• The iliopsoas muscle, crucial for hip flexion, comprises the iliacus and psoas major.
• Optimal SS duration for iliacus muscle stiffness reduction is not well-established.

Purpose of the Study:

• To determine the time course of iliacus muscle stiffness reduction following static stretching.

Main Methods:

• Twenty-six healthy males underwent hip extension SS.
• Ultrasonic shear wave elastography measured iliacus muscle shear elastic modulus (stiffness).
• Measurements were taken before and after each 1-minute SS bout, up to five bouts.

Main Results:

• A statistically significant effect of time on iliacus muscle stiffness was observed.
• Iliacus muscle stiffness significantly decreased after 1 to 5 SS bouts compared to baseline.
• Stiffness showed a further significant reduction after 5 SS bouts compared to 1 SS bout.

Conclusions:

• Static stretching effectively reduces iliacus muscle stiffness.
• Even a single 1-minute bout of SS can decrease iliacus muscle stiffness.
• Cumulative SS, up to 5 minutes, leads to greater reductions in iliacus muscle stiffness.