Differences in EMG activity during exercises targeting the scapulothoracic region: a preliminary study

Area of Science:

• Biomechanics
• Exercise Physiology
• Sports Medicine

Background:

• The serratus anterior muscles (middle and lower) and upper trapezius are crucial for scapular stability and movement.
• Understanding muscle activation patterns during various exercises is essential for effective training and rehabilitation.
• Previous research has explored shoulder and scapular muscle activation, but specific comparisons for serratus anterior engagement are less defined.

Purpose of the Study:

• To compare the surface electromyographic (sEMG) activity of the middle serratus anterior (MSA), lower serratus anterior (LSA), and upper trapezius (UT) muscles across different exercises.
• To identify exercises that selectively activate the MSA and LSA.
• To determine the optimal exercises for targeting serratus anterior muscles, considering potential over-activation of the upper trapezius.

Main Methods:

• Sixteen healthy, physically active volunteers participated in the study.
• Surface electromyography (sEMG) was used to record muscle activity.
• Participants performed five exercises: arm elevation above 120°, diagonal elevation, dynamic hug, dynamic hug plus, and push-up plus.

Main Results:

• The dynamic hug plus exercise demonstrated significantly higher MSA activation compared to other exercises (P < 0.05).
• Diagonal elevation, dynamic hug plus, and push-up plus exercises showed significantly greater LSA activation than arm elevation above 120° and dynamic hug (P < 0.05).
• The UT muscle and UT/MSA and UT/LSA ratios were significantly higher during arm elevation and diagonal shoulder flexion compared to dynamic hug, dynamic hug plus, and push-up plus exercises (P < 0.05).

Conclusions:

• The dynamic hug plus exercise is effective for activating both the MSA and LSA.
• Exercises incorporating a scapular protraction component, such as dynamic hug plus and push-up plus, are superior for achieving selective activation of the LSA and MSA.
• These findings suggest that specific exercise selection can optimize serratus anterior engagement while potentially minimizing upper trapezius over-recruitment.