Acromiohumeral Distance During Neuromuscular Electrical Stimulation of the Lower Trapezius and Serratus Anterior Muscles in Healthy Participants.
BACKGROUND
Compromise to the acromiohumeral distance has been reported in participants with subacromial impingement syndrome compared with healthy participants. In clinical practice, patients with subacromial shoulder impingement are given strengthening programs targeting the lower trapezius (LT) and serratus anterior (SA) muscles to increase scapular posterior tilt and upward rotation. We are the first to use neuromuscular electrical stimulation to stimulate these muscle groups and evaluate how the muscle contraction affects the acromiohumeral distance.


OBJECTIVE
To investigate if electrical muscle stimulation of the LT and SA muscles, both separately and simultaneously, increases the acromiohumeral distance and to identify which muscle-group contraction or combination most influences the acromiohumeral distance.


METHODS
Controlled laboratory study.


METHODS
Human performance laboratory.


METHODS
Twenty participants (10 men and 10 women, age = 26.9 ± 8.0 years, body mass index = 23.8) were screened.


METHODS
Neuromuscular electrical stimulation of the LT and SA.


METHODS
Ultrasound measurement of the acromiohumeral distance.


RESULTS
Acromiohumeral distance increased during contraction via neuromuscular electrical stimulation of the LT muscle (t(19) = -3.89, P = .004), SA muscle (t(19) = -7.67, P = .001), and combined LT and SA muscles (t(19) = -5.09, P = .001). We observed no differences in the increased acromiohumeral distance among the 3 procedures (F(2,57) = 3.109, P = .08).


CONCLUSIONS
Our results supported the hypothesis that the muscle force couple around the scapula is important in rehabilitation and scapular control and influences acromiohumeral distance.
Department of Health, Sports, and Rehabilitation Sciences, University of Salford, United Kingdom;
Alya H
AH
Bdaiwi
Department of Health, Sports, and Rehabilitation Sciences, University of Salford, United Kingdom;
Tanya Anne
TA
Mackenzie
Department of Health, Sports, and Rehabilitation Sciences, University of Salford, United Kingdom;
Lee
L
Herrington
English Institute of Sport, Manchester, United Kingdom;
Ian
I
Horsley
Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Belgium.
Ann M
AM
Cools
D000174:Acromion / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D000328:Adult; D004558:Electric Stimulation; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D006811:Humerus / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D064169:Intermediate Back Muscles / Q000502:physiology*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D012399:Rotation; D012540:Scapula / Q000000981:diagnostic imaging / Q000502:physiology; D019534:Shoulder Impingement Syndrome / Q000473:pathology / Q000503:physiopathology; D064171:Superficial Back Muscles / Q000502:physiology*; D014463:Ultrasonography
real-time ultrasound; rehabilitation; subacromial impingement syndrome