Influence of Pectoralis Minor and Upper Trapezius Lengths on Observable Scapular Dyskinesis

Abstract Objectives: Although a relationship between short pectoralis minor and upper trapezius and scapular dyskinesis has been postulated, no studies have investigated this theory. Understanding the effect of these muscle lengths on observable scapular dyskinesis may aid in determining risks and therefore making treatment decisions. Being aware of the magnitude of this effect would help gauge the significance of risks involved. Our aim was to evaluate the influence of pectoralis minor and upper trapezius lengths on scapular dyskinesis. Design Cross-sectional study. Setting University research laboratory. Participants Asymptomatic participants (n=148;296 arms) were evaluated. Main outcome measures Scapular Dyskinesis Test (SDT) was used to identify scapular dyskinesis, Pectoralis Minor Index (PMI) and Upper Trapezius Length Testing were used to determine muscle length. Results SDT+ arms had shorter pectoralis minor resting length (PMI:7.49±0.38) (p