Passive force, angle, and stiffness changes after stretching of hamstring muscles.

Area of Science:

• Biomechanics
• Exercise Physiology
• Sports Medicine

Background:

• Periodic stretching programs are known to increase joint range of motion.
• Mechanisms include changes in muscle tissue properties and stretch tolerance.
• Limited research has explored changes in passive resistive forces related to range of motion gains.

Purpose of the Study:

• To investigate the effects of a 6-week hamstring stretching program.
• To assess changes in knee extension range of motion.
• To evaluate alterations in passive resistive forces and muscle stiffness.

Main Methods:

• A randomized control trial with 43 school-age subjects.
• Intervention group performed 6-week hamstring stretching program (5 days/week, 3 reps, 30s hold).
• Control group did not participate in stretching; measurements taken pre- and post-intervention.

Main Results:

• Significant increases in knee extension range of motion observed in the intervention group (P < 0.05).
• Significant increases in passive resistive force and muscle stiffness were noted in the intervention group.
• No significant changes were found in the control group for these variables.

Conclusions:

• Consistent with literature, 6-week stretching programs yield significant improvements in knee extension range of motion.
• Increased muscle stiffness in the newly acquired range of motion suggests potential structural changes.
• Findings provide evidence supporting structural adaptations in muscles following a consistent stretching regimen.