Cryotherapy induces an increase in muscle stiffness

Area of Science:

• Sports Medicine
• Biophysics
• Physiology

Background:

• Cryotherapy is frequently used in sports for injury treatment and muscle damage prevention.
• However, its impact on muscle mechanical properties, specifically stiffness, remains unclear.

Purpose of the Study:

• To investigate the effect of air-pulsed cryotherapy on muscle stiffness.
• To assess changes in muscle mechanical properties using ultrasound shear wave elastography.

Main Methods:

• Muscle temperature, myoelectrical activity, ankle passive torque, and shear modulus (stiffness) of the gastrocnemius medialis were measured.
• Measurements were taken before, during, and for 40 minutes after a cryotherapy treatment protocol (-30°C; 4 sets of 4 minutes with 1-minute recovery).

Main Results:

• Muscle temperature significantly decreased and remained below baseline for an hour post-treatment.
• Shear modulus, an indicator of muscle stiffness, increased significantly after cryotherapy and remained elevated for the entire post-treatment period.

Conclusions:

• Air-pulsed cryotherapy demonstrably increases muscle stiffness.
• This acute alteration in muscle mechanical properties may reduce the tolerance to stretch, potentially increasing injury risk in athletic contexts.