Stretching Effects: High-intensity & Moderate-duration vs. Low-intensity & Long-duration

Area of Science:

• Biomechanics
• Exercise Physiology
• Sports Science

Background:

• Stretching protocols vary in intensity and duration, influencing acute adaptations.
• Understanding these differences is crucial for optimizing flexibility and performance.

Purpose of the Study:

• To compare the acute effects of high-intensity, moderate-duration stretching versus low-intensity, long-duration stretching on knee-flexor muscles.
• To investigate changes in passive torque, maximal range of motion (ROM), and muscle activity.

Main Methods:

• 17 volunteers underwent two stretching protocols: high-intensity (100% max tolerable passive torque, ~244s) and low-intensity (50% tolerable passive torque, 900s).
• Measurements included passive torque, peak passive torque, maximal ROM, and muscle activity pre- and post-stretching (1, 30, 60 min intervals).

Main Results:

• High-intensity stretching significantly increased maximal ROM and peak passive torque at all time points (p<0.05).
• Low-intensity stretching did not significantly alter maximal ROM or peak passive torque (p>0.05).
• Passive torque decreased acutely post-stretching in both groups, with a greater reduction in the low-intensity group. 30 minutes post-stretch, passive torque returned to baseline for low-intensity and increased above baseline for high-intensity.

Conclusions:

• High-intensity stretching is superior for increasing maximal ROM and peak passive torque acutely.
• Low-intensity, long-duration stretching is most effective for acutely decreasing passive torque.
• High-intensity, moderate-duration stretching can increase passive torque above baseline levels within 30 minutes post-intervention.