Baseline Has no Effect on Change in Forward Shoulder Posture, Range of Motion, and Muscle Excitation Following Myofascial Release: A Velocity-dependent Investigation

Purpose: Rate dependence, where the initial value of a variable plays a crucial role in determining the extent and/or direction of change following an intervention, is a known factor contributing to an individual’s response to drug and non-drug interventions. Surprisingly, it is not known if there is a rate-dependent effect on outcomes following a massage therapy intervention. We assessed whether there is a rate-dependent effect on forward shoulder posture (FSP), pectoralis major length (PECL), and muscle excitation of the upper (UT), middle (MT), and lower trapezius (LT), and pectoralis major (PEC) following 4 minutes of myofascial release (MFR) to the pectoral fascia. Methods: Fifty-nine right-handed participants (27±9 years, 30 females) with FSP, but otherwise asymptomatic shoulders with one MFR treatment administered by a registered massage therapist were recruited. FSP, PECL, and muscle excitation during a reaching task were measured before (PRE) and after the treatment (POST). Correlations were conducted on the difference between PRE and POST values and the sum of PRE and POST values divided by two for all variables. Results: There were no significant correlations between change scores and the average PRE and POST scores for any variable. Conclusion: There is no rate-dependent effect on FSP, PECL, and muscle excitation following a 4-minute MFR intervention. These results are the first to suggest that baseline characteristics do not influence individual responses to a massage intervention. Future work should aim to determine whether speed dependence varies with different doses and types of massage interventions and patient-reported outcomes (pain, anxiety, function, etc.) and muscle/tissue characteristics (stiffness, etc.).