Resting position variables at the shoulder: evidence to support a posture-impairment association.
OBJECTIVE
A relationship between posture and impairment at the shoulder is theorized, but not supported by evidence. It is proposed that posture and impairment are not directly related, but linked by movement dysfunction. The purpose of this analysis was to explore the relationships among posture, pectoralis minor muscle length, and movement alterations at the shoulder.


METHODS
Subjects who were asymptomatic for shoulder pathology were divided into 2 groups of 25 subjects each based on normalized pectoralis minor muscle resting length.


METHODS
Scapula orientation, thoracic kyphosis, and pectoralis minor muscle lengths were measured, and ratios and indexes of postural variables were calculated. All variables were analyzed for correlations and group differences.


RESULTS
Significant group differences were demonstrated for several posture variables, including thoracic spine kyphosis and scapular internal rotation. The distance from the sternal notch to the coracoid process demonstrated the highest correlation with pectoralis minor muscle length.


CONCLUSIONS
The findings indicate a relationship between posture and pectoralis minor muscle length and support a proposed model linking posture, an anatomical variable, movement dysfunction, and impairment.
Physical Therapy Division, Ohio State University, 516 Atwell Hall, 453 W Tenth Ave, Columbus, OH 43210, USA. borstad.1@osu.edu
John D
JD
Borstad
D000328:Adult; D001696:Biomechanical Phenomena; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000503:physiopathology; D008297:Male; D010369:Pectoralis Muscles / Q000033:anatomy & histology / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D012146:Rest / Q000502:physiology*; D012399:Rotation; D012540:Scapula / Q000502:physiology; D012782:Shoulder / Q000502:physiology*; D013904:Thoracic Vertebrae / Q000503:physiopathology