The optimal duration of high-intensity static stretching in hamstrings.

Area of Science:

• Biomechanics
• Sports Science
• Human Physiology

Background:

• Static stretching is commonly used to improve flexibility.
• The optimal duration of high-intensity static stretching for balancing flexibility and strength is not well-established.
• Understanding these effects is crucial for designing effective training and rehabilitation programs.

Purpose of the Study:

• To compare the effects of different durations (10, 15, and 20 seconds) of high-intensity static stretching on hamstring flexibility and strength.
• To determine if stretching duration influences changes in range of motion, passive torque, muscle-tendon unit stiffness, and isokinetic strength.

Main Methods:

• Fourteen healthy males performed high-intensity static hamstring stretching at maximum discomfort for 10, 15, or 20 seconds.
• Measurements included range of motion, peak passive torque, relative passive torque, muscle-tendon unit stiffness, and isokinetic knee flexion peak torque.
• Pain levels were assessed using a numerical rating scale.

Main Results:

• All stretching durations significantly increased range of motion, peak passive torque, and knee angle at peak torque.
• Relative passive torque and muscle-tendon unit stiffness decreased across all durations.
• Peak torque decreased after 10 seconds of stretching but remained unchanged after 15 or 20 seconds.

Conclusions:

• High-intensity static stretching effectively enhances hamstring flexibility and reduces muscle-tendon unit stiffness, irrespective of duration.
• A stretching duration of 10 seconds may negatively impact hamstring peak torque, while durations of 15 seconds or longer appear to mitigate this strength loss.