i Myofascial Release of the Pectoral Fascia: Effect on Shoulder Posture, Pectoral Length, Muscle Activity, and Movement Performance by: Sarah Bohunicky A Thesis submitted to the Faculty of Graduate Studies of The University of Manitoba in partial fulfillment of the requirements of the degree of MASTER OF SCIENCE Faculty of Kinesiology and Recreation Management University of Manitoba Winnipeg June 23rd, 2021 Copyright © 2021 by Sarah Bohunicky ii Abstract Context: Neck-shoulder pain is among the most common health care problems, especially in office workers and females. Forward shoulder posture (FSP) is a common postural deviation and known risk factor for the development of neck-shoulder pain and pathology. Common approaches for reducing FSP include stretching and performing manual techniques to increase the length and extensibility of the scapular protractors and strengthening the scapular retractors. Myofascial release (MFR) is a group of manual techniques that elongate and soften restricted fascia, however, the effects of myofascial release to the pectorals on FSP are currently unknown. Objective: To determine the impact of 4-minutes of MFR on: 1) FSP, 2) pectoral length, 3) muscle activity of the upper, middle, and lower trapezius and pectoralis major, 4) scapular retractor to protractor ratio of activity, and 4) movement performance compared to a soft-touch control. Participants: Eighteen females (27 years ± 10) with FSP but otherwise healthy shoulders. Interventions: One 4-minute MFR treatment and one 4-minute soft-touch control (CON) treatment. Main Outcome Measures: FSP, pectoral length, muscle activity of upper, middle, and lower trapezius (UT, MT, LT) and pectoralis major (PEC), scapular retractor-protractor ratio of activity (R/P), and movement performance (reaction time [RT], movement time [MvT], end-point accuracy [constant and variable error]). Statistical Analysis: Two-way (treatment [MFR or CON] by time [PRE and POST]) repeated measures analysis of variance (ANOVA) was conducted on all dependent variables. Results: There was a statistically significant decrease in FSP, F(1, 17) = 6.66, p = .019, partial η2= .282. The means (millimetres) and standard deviations were as follows: PRE-MFR 124 (15), POST-MFR 118 (14), PRE-CON 124 (15), POST-CON 122 (15). There were no statistically significant changes in pectoral length, muscle activity, or movement performance. Conclusion: A 4-minute MFR to the pectoral fascia is effective at reducing FSP, but does not impact pectoral length, muscle activity, or movement performance. However, the study sample was well underpowered, thus possibly impacting the results of the other outcome variables. It is unclear if this reduction in FSP is considered clinically significant in reducing the risk for development of neck-shoulder pain or pathology. iii Acknowledgements When I made the decision to return to school to complete my Master of Science degree, I do not think I ever could have anticipated the road that lied ahead. The ebbs and flows of graduate studies are more challenging, frustrating, and exhausting than I ever imagined, yet rewarding, exciting, and fulfilling all at once. The tremendous support I have received from family, friends, lab mates, colleagues, professors, and supervisors is truly humbling and overwhelming and has helped get me through this seemingly endless degree (thanks to COVID-19). I am proud of my work thus far in graduate studies and cannot wait to see where my academic pursuits take me. I have overcome many barriers, some of which were unprescendented, and for that, I thank you all for pushing me when I didn’t want to push myself. First and foremost, I want to thank my supervisor, Dr. Trisha Scribbans. In January 2018, when we first discussed me pusuing graduate studies under your supervision, I never would have imagined our working relationship to be as seamless and enjoyable as it now is. I have never had another person outside my family wanting to see me as wildly successful as you do. Your personal, academic, and professional support, mentorship, and guidance is truly astounding and words cannot express my gratitude for you enough. I am very much looking forward to the many years we have left working together. Secondly, I would like to thank my other committee members Dr. Cheryl Glazebrook and Dr. Joanne Parsons for their valuable support, input, and expertise on the project. In particular, I would like to thank Dr. Glazebrook for the numerous hours she spent advising and guiding me through the use of E-Prime and scripting letters of reference. Thirdly, I would like to thank my lab mates in the Integrative Musculoskeletal Research Lab for their knowledge, patience, and support throughout my degree. I could not have asked for a better group of grad students-turned-friends to go through this experience with. Thank you for your help with piloting, listening to my 3MT about 50 times, and fueling me with coffee, high- fives, and laughs, even on the darkest of grad school days. I would especially like to thank Zach for his non-judgemental help with research, ethics, analysis, and all things stats related. I thoroughly enjoyed learning from you and participating in “tea-time.” Lastly, but certainly not least, I would like to thank my parents, Bernie and Diane. “Thank-you” doesn’t seem like enough for your endless emotional, personal, and yes, financial support. You two have and will always be my rock, and I am forever grateful to have such supportive, loving, and compassionate parents. Thank-you for always supporting my endeavors and encouraging me in ways I would not be able to do for myself. Thank-you for being my shoulders to cry on, my personal bartenders and chefs, the ones who make me laugh (even when I don’t want to), the ones to jump up and down in celebration with, and my persistent force to do the absolute best I can. Without you, I would not be where I am or who I am today. “This is an investment in your future”- my Dad This project was supported by the Massage Therapy Research Foundation, College of Massage Therapists of Ontario, and Massage Therapy Association of Manitoba iv Table of Contents Abstract ........................................................................................................................................... ii Acknowledgements ........................................................................................................................ iii List of Tables ................................................................................................................................ vii List of Figures .............................................................................................................................. viii 1. Introduction ........................................................................................................................... 10 2. Review of the Literature ........................................................................................................... 13 2.1 Shoulder Complex Applied Anatomy Review ............................................................. 13 2.1.1 Sternoclavicular, Glenohumeral, and Acromioclavicular Joints ................................. 13 2.1.2 Scapulothoracic Joint ................................................................................................... 14 2.1.3 Scapular Protractors ..................................................................................................... 15 2.1.4 Scapular Retractors ...................................................................................................... 16 2.1.5 Fascia ........................................................................................................................... 17 2.1.6 Pectoral Fascia ............................................................................................................. 17 2.1.7 Fascial Adhesions and Trigger Points .......................................................................... 18 2.1.8 Implications of Fascial Adhesions and Trigger Points ................................................ 19 2.2 Posture ................................................................................................................................. 20 2.3 Reciprocal Inhibition .......................................................................................................... 22 2.4 Movement Performance ...................................................................................................... 23 2.4.1 Speed-Accuracy Trade Off (aka Fitts’ Law) ............................................................... 23 2.4.2 Schema Theory ............................................................................................................ 24 2.4.3 Applicability to Whole-Limb Real Movements .......................................................... 25 2.5 MSK Disorders ................................................................................................................... 26 2.5.1 Work-Related Musculoskeletal Disorders ................................................................... 27 2.5.2 MSK Disorders in Office Jobs ..................................................................................... 28 2.5.3 Changes in Muscle Activity Due to MSK Disorders ................................................... 29 2.5.4 MSK Disorder Risk Factors ......................................................................................... 30 2.5.4a Sex Differences .....................................................................................................