The effects of manual treatment on rounded-shoulder posture, and associated muscle strength

A relationship between pectoralis minor muscle tightness and rounded shoulder posture (RSP) has been suggested, but evidence demonstrating that treatment aimed at the pectoralis minor affects posture or muscle function such as lower trapezius strength (LTS) remains lacking. In this randomized, blinded, controlled study of the 56 shoulders of 28 healthy participants, the experimental treatment consisting of pectoralis minor soft tissue mobilization (STM) and self-stretching significantly reduced RSP compared to the pre-treatment baseline (Friedman test, p<.001) and the control treatment of placebo touch and pectoralis major self-stretching (Mann-Whitney U-test, p<.01). RSP remained significantly reduced 2 weeks after the single treatment. Both control and experimental treatments resulted in increased LTS (Friedman test, p<.01) with no significant difference in LTS noted between treatments (p>.05). This study demonstrated that STM and self-stretching of the pectoralis minor can significantly reduce RSP.