Hamstring functions during hip-extension exercise assessed with electromyography and magnetic resonance imaging

Area of Science:

• Biomechanics
• Muscle Physiology
• Imaging Techniques

Background:

• Understanding muscle activation patterns is crucial for exercise science and rehabilitation.
• Hamstring muscle recruitment during hip extension is complex and requires precise measurement.
• Electromyography (EMG) and muscle functional MRI (mfMRI) offer complementary insights into muscle function.

Purpose of the Study:

• To compare muscle recruitment patterns in hamstring muscles during hip extension exercise.
• To evaluate the efficacy of EMG and mfMRI in assessing muscle activation.
• To identify which hamstring muscles are predominantly involved in hip extension.

Main Methods:

• Six male volunteers performed hip extension exercises.
• Electromyography (EMG) recorded activity in biceps femoris long head (BFlh), semitendinosus (ST), and semimembranosus (SM).
• Muscle functional MRI (mfMRI) measured T2 values and cross-sectional areas (CSAs) of these muscles at rest and post-exercise.

Main Results:

• EMG revealed significantly higher activity in BFlh and SM compared to ST.
• mfMRI showed a significant increase in SM's T2 value and CSA immediately after exercise.
• These findings suggest differential recruitment of hamstring muscles during hip extension.

Conclusions:

• The biceps femoris long head (BFlh) and semimembranosus (SM) are selectively recruited during hip extension exercise.
• EMG and mfMRI are valuable tools for assessing muscle recruitment patterns.
• This research contributes to a deeper understanding of hamstring muscle function during dynamic movements.