■ Background and purpose
Abnormal scapular alignments lead to various shoulder injuries. Lower trapezius muscle has an important role in normal scapular movements and alignments. In the previous study, although additional cues of lower trapezius actions (e.g., scapular adduction and depression) were applied for increasing lower trapezius muscle activity, lower trapezius muscle activity was not significantly changed. However, previous study considered only scapular adduction and depression, and cues of scapular posterior tilt, another important action of lower trapezius, were not provided. Considering that lower trapezius acts as agonist for scapular posterior tilt, intended scapualr posterior tilt may increase lower trapezius muscle activity. To develop exercise for facilitating lower trapezius muscle activity, the effects of exercise combined with actions of lower trapezius need to be demonstrated. Thus, the present study will examine the effects of additional cues of scapular posterior tilt on muscle activity of trapezius muscles during arm lifting exercises with and without scapualr addution and depression.

■ Subjects
15 healthy adults without shoulder pain

■ Exercises
- General arm lifting exercise: Subjects perform arm lifting with 125° of shoulder abduction and shoulder external rotation in prone.
- Scapular posterior tilt training: Subjects pull away acromion backward.
- Arm lifting exercise with cues of scapular posterior tilt: Subjects perform arm lifting with 125° of shoulder abduction, shoulder external rotation, and scapular posterior tilt in prone
- Arm lifting exercise with cues of scapular adduction, depression, and posterior tilt: Subjects performed arm lifting with scapular adduction and depression while maintaining scapualr posterior tilt in prone.

■ Measures
- Muscle activity (upper trapezius, middle trapezius, lower trapezius)
- Scapular posterior tilt angle

■ Hypothesis
Additional cues of scapular posterior tilt will increase lower trapezius muscle activity during arm lifting exercises.

Prevention

■  General arm lifting exercise 
- Subjects place shoulder at 125° of shoulder abduction with shoulder external rotation. 
- Subjects performed arm lifting and maintain end-position for 5 second, and repeat three times. 
■  Scapular posterior tilt training 
- The examiner attach the motion sensor on the placement between root of scapular spine and inferior angle of scapular of subject
- Subjects perform scapular posterior tilt training (pull away acromion backward) for 10 minutes 
- During tranining, subjects perform active scapular posterior tilt using tablet PC with biofeedback training system program
- An examiner monitor compensatory movements such as scapular adduction without scapular posterior tilt and scapular downward rotation. 
■  Arm lifting exercise with cues of scapular posterior tilt 
- After scapular posterior tilt training, subjects place shoulder at 125° of shoulder abduction with shoulder external rotation. 
- Subjects perform intended scapluar posterior tilt and then arm lifting. 
- Subjects maintain end-position for 5 seconds and repeat three times. 
■  Arm lifting exercise with cues of scapular adduction, depression, and posterior tilt 
- After scapular posterior tilt training, subjects place shoulder at 125° of shoulder abduction with shoulder external rotation. 
- Subjects perform intended scapluar posterior tilt and then arm lifting with scapular adduction and depression. 
- Subjects maintain end-position for 5 seconds and repeat three times.

Arm Label

Target Number of Participant

Arm Type

Arm Description

1) General arm lifting exercise 
- Subjects place shoulder at 125° of shoulder abduction with shoulder external rotation. 
- Subjects performed arm lifting and maintain end-position for 5 second, and repeat three times. 
2) Scapular posterior tilt training 
- The examiner attach the motion sensor on the placement between root of scapular spine and inferior angle of scapular of subject
- Subjects perform scapular posterior tilt training (pull away acromion backward) for 10 minutes 
- During tranining, subjects perform active scapular posterior tilt using tablet PC with biofeedback training system program
- An examiner monitor compensatory movements such as scapular adduction without scapular posterior tilt and scapular downward rotation. 
3) Arm lifting exercise with cues of scapular posterior tilt 
- After scapular posterior tilt training, subjects place shoulder at 125° of shoulder abduction with shoulder external rotation. 
- Subjects perform intended scapluar posterior tilt and then arm lifting. 
- Subjects maintain end-position for 5 seconds and repeat three times. 
4) Arm lifting exercise with cues of scapular adduction, depression, and posterior tilt 
- After scapular posterior tilt training, subjects place shoulder at 125° of shoulder abduction with shoulder external rotation. 
- Subjects perform intended scapluar posterior tilt and then arm lifting with scapular adduction and depression. 
- Subjects maintain end-position for 5 seconds and repeat three times.

Gender

Age

Description

Healthy adults

Individuals who have history of diagnosis for tendinitis, adhesive capsulitis, or subacromial impingement,

Muscle activity (upper trapezius, middle trapezius, lower trapezius)

During each arm lifting exercise (general arm lifting exercise, arm lifting exercise with cues of scapular posterior tilt, arm lifting exercise with cues of scapular adduction, depression, and posterior tilt)

Scapular posterior tilt angle

Prone with 125° of shoulder abduction and shouler external rotation with and without intended scapular posterior tilt