Piriformis electromyography activity during prone and side-lying hip joint movement

Area of Science:

• Biomechanics
• Kinesiology
• Human Movement Science

Background:

• The piriformis muscle plays a crucial role in hip function, particularly in external rotation and abduction.
• Understanding piriformis activation during various hip movements is essential for rehabilitation and athletic performance.
• Previous research has utilized surface electromyography, but fine-wire electrodes offer more precise measurements of deep muscles like the piriformis.

Purpose of the Study:

• To quantify the electromyographic (EMG) activity of the piriformis muscle during seven distinct hip movements.
• To compare piriformis activation across different hip rotation and extension exercises.
• To identify specific hip movements that maximally engage the piriformis muscle.

Main Methods:

• Eleven healthy male participants were enrolled in the study.
• Fine-wire electrodes were inserted into the piriformis muscle, with surface electrodes placed on surrounding hip and trunk muscles.
• EMG amplitude was recorded during seven standardized hip movements, including variations of side-lying abduction and prone hip extension.

Main Results:

• The highest piriformis EMG activity was observed during prone hip extension combined with external rotation.
• This specific movement also demonstrated significant activation of both the superior and inferior portions of the gluteus maximus.
• Other tested hip movements showed lower, varying levels of piriformis activation.

Conclusions:

• Prone hip extension in external rotation is a highly effective exercise for activating the piriformis muscle.
• This exercise also strongly engages the gluteus maximus, suggesting its utility in gluteal strengthening programs.
• The findings provide valuable data for designing targeted exercise protocols for hip musculature.