Stretching Positions and Techniques of the Pectoralis Minor Muscle in Population with Forward Shoulder: Scapular Kinematics, Flexibility and Performance
Date Issued
2011
Date
2011
Author(s)
Yang, Pei-Lin
Abstract
Forward shoulder posture commonly complaints in the shoulder area also showed the highest prevalence. One of the mechanisms inducing forward shoulder posture is pectoralis minor tightness. Therefore, causing shoulder is pulled forward and accompanying with changes of scapular kinematics and muscle performance. The purposes of this study are aimed: (1) to test the relationship between the scapular kinematics and pectoralis minor flexibility, including length and tightness; (2) to investigate stretch effect on posture, pectoralis minor flexibility, scapular kinematics and associated muscle performance and (3) to determine which stretching positions and techniques can obtain greatest stretch effect. The following measurements were collected: (1) total scapular distance (TSD: T3 spinous process to the inferior angle of the acromion); (2) shoulder elevation range of motion in scapular plane; (3) length of pectoralis minor; (4) three-dimensional scapular kinematics during shoulder scaption; (5) tightness of pectoralis minor; and (6) shoulder muscle strength. After the initial evaluation, the specific stretch protocol was applied to the subject. Then, the second evaluation was immediately performed to collect data again. Within the following two weeks, stretch protocol continues and subject returned to receive follow-up data collection after two weeks. For the first purpose to test the relationship between the scapular kinematics and pectoralis minor flexibility, including length and tightness, the Pearson product-moment coefficient of correlation was used. For the second and third purposes, 2-way mixed ANOVAs with group (4 levels: self-30, self-90, manual-30, manual-90) and time (3 levels: pre, post, follow-up) factors was used to investigate stretch effect on each outcome including posture, pectoralis minor muscle flexibility, scapular kinematics and scaption performance. Totally 28 subjects were included and data were analyzed. Only fair relationship between pectoralis minor length and scapular tipping (r = 0.261). TSD, ROM, STRE and TIP showed the simple effect of time (P < 0.05). TSD and TIP showed the simple effect of group (P < 0.05). The Self-30 subgroup corrected the forward shoulder posture significantly. And the Manual-30 subgroup increased the scapular posterior tipping during performing shoulder scaption. Overall, stretch at the 30 degrees of abduction in the scapular plane, both techniques should be included in the population with forward shoulder.
Subjects
Posture
Stretching
Pectoralis minor
Scapula
Kinematic
Type
thesis
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