Shoulder horizontal abduction stretching effectively increases shear elastic modulus of pectoralis minor muscle.
BACKGROUND
Stretching maneuvers for the pectoralis minor muscle, which involve shoulder horizontal abduction or scapular retraction, are performed in clinical and sports settings because the tightness of this muscle may contribute to scapular dyskinesis. The effectiveness of stretching maneuvers for the pectoralis minor muscle is unclear in vivo. The purpose of this study was to verify the effectiveness of stretching maneuvers for the pectoralis minor muscle in vivo using ultrasonic shear wave elastography.


METHODS
Eighteen healthy men participated in this study. Elongation of the pectoralis minor muscle was measured for 3 stretching maneuvers (shoulder flexion, shoulder horizontal abduction, and scapular retraction) at 3 shoulder elevation angles (30°, 90°, and 150°). The shear elastic modulus, used as the index of muscle elongation, was computed using ultrasonic shear wave elastography for the 9 aforementioned stretching maneuver-angle combinations.


RESULTS
The shear elastic modulus was highest in horizontal abduction at 150°, followed by horizontal abduction at 90°, horizontal abduction at 30°, scapular retraction at 30°, scapular retraction at 90°, scapular retraction at 150°, flexion at 150°, flexion at 90°, and flexion at 30°. The shear elastic moduli of horizontal abduction at 90° and horizontal abduction at 150° were significantly higher than those of other stretching maneuvers. There was no significant difference between horizontal abduction at 90° and horizontal abduction at 150°.


CONCLUSIONS
This study determined that shoulder horizontal abduction at an elevation of 90° and horizontal abduction at an elevation of 150° were the most effective stretching maneuvers for the pectoralis minor muscle in vivo.
Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Rehabilitation Unit, Kyoto University Hospital, Kyoto, Japan. Electronic address: umehara.jun.77z@st.kyoto-u.ac.jp.
Jun
J
Umehara
Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan.
Masatoshi
M
Nakamura
Rehabilitation Group, Department of Medical Technique, Nagoya University, Nagoya, Japan.
Kosuke
K
Fujita
Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Ken
K
Kusano
Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Satoru
S
Nishishita
Department of Rehabilitation, Sapporo Tokushukai Hospital, Sapporo, Japan.
Kojiro
K
Araki
Rehabilitation Unit, Kyoto University Hospital, Kyoto, Japan.
Hiroki
H
Tanaka
Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Ko
K
Yanase
Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Noriaki
N
Ichihashi
D000328:Adult; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D052580:Muscle Stretching Exercises; D010369:Pectoralis Muscles / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology; D012540:Scapula / Q000502:physiology; D012782:Shoulder / Q000502:physiology*; D019534:Shoulder Impingement Syndrome / Q000534:rehabilitation; D013177:Sports
Stretching; pectoralis minor muscle; rehabilitation; shear elastic modulus; shoulder horizontal abduction; ultrasonic shear wave elastography