The association between upper trapezius activity and thorax movement in classical singing

Area of Science:

• Physiology of singing
• Biomechanics of vocal production
• Respiratory muscle function

Background:

• The upper trapezius (TR) muscle's role in classical singing is not fully understood.
• Investigating the coordination between TR activity and thoracic movement is crucial for vocal pedagogy.

Purpose of the Study:

• To analyze the timing of upper trapezius (TR) muscle activity in relation to upper and lower thorax movement.
• To examine the phasing of TR activity with intercostal (INT) and lateral abdominal (OBL) muscles during singing.
• To assess the effect of biofeedback (BF) on TR activity and thoracic movement.

Main Methods:

• Electromyography (EMG) recorded TR, INT, and OBL muscle activity.
• Strain gauges measured upper and lower thorax circumference changes.
• Singing tasks were performed at varying loudness before and after TR biofeedback.

Main Results:

• A distinct phasing pattern was observed where TR, INT, and OBL muscles supported expiration.
• Upper TR activity was found to contribute to upper thorax compression during phonation, acting as an accessory expiratory muscle.
• Biofeedback significantly reduced TR EMG activity, leading to increased upper thorax circumference and reduced respiratory movement post-intervention.

Conclusions:

• Upper trapezius activity is coordinated with other respiratory muscles during singing, specifically aiding expiration.
• Biofeedback is an effective method for reducing excessive upper trapezius muscle engagement in singers.
• Modifying TR activity can positively influence thoracic mechanics and vocal production.