Acute Effects of Static Stretching Duration on a Single-Leg Balance Task

Area of Science:

• Biomechanics
• Sports Science
• Physical Therapy

Background:

• Static stretching (SS) is commonly used to improve range of motion.
• The optimal duration of SS for maintaining or improving balance is not well understood.
• Understanding SS effects on balance is crucial for athletes and rehabilitation.

Purpose of the Study:

• To investigate the effect of different static stretching durations on balance.
• To determine if SS duration influences postural sway and standing stability.
• To assess changes in joint mobility and muscle activity following SS.

Main Methods:

• Twenty-two participants underwent passive dorsiflexion and single-leg balance tests.
• Static stretching was applied to ankle and metatarsophalangeal joints for 30s x 1, 2, or 4 sets.
• Measurements included maximal dorsiflexion angle, passive torque, muscle-tendon junction displacement, electromyography, center of pressure (COP) sway, and standing duration.

Main Results:

• Two sets of SS significantly increased COP displacement and velocity, indicating greater postural sway.
• One and four sets of SS did not significantly alter COP displacement or velocity.
• Maximal dorsiflexion angle and passive torque increased post-SS, but muscle-tendon junction displacement and electromyography did not change.
• No significant gender differences were observed in balance changes.

Conclusions:

• Static stretching duration influences postural sway, with two sets specifically increasing COP displacement and velocity.
• While SS improves joint mobility (dorsiflexion angle, passive torque), its duration is critical for balance control.
• These findings suggest careful consideration of SS protocols to avoid potential negative impacts on balance.