As Upper trapezius and levator scapulae are the most common postural muscles that tends to get shorten leading to restricted neck mobility as they are most frequently used to maintain posture,there seems to be strong rationale for stretching these muscles however, to date there is no agreement about the optimal stretching parameters . A multitude of stretching parameters are used in the clinical setting. However, there is no convincing evidence to suggest which parameters are most effective in the management of Chronic myofascial pain syndrome . In this regard, although the stretching duration is considered one of the most important variables that can affect the treatment outcome, to date there is little agreement on the most effective stretching duration.~In theory, reflex inhibition during the stretching procedure, an increased stretch tolerance , decreased viscoelasticity, and a degree of reduced musculotendinous stiffness could all contribute to the sustained increase in elastic ROM. Regardless of these proven underlying mechanisms, all the previous studies ignored the adverse mechanical tension that developed during stretching exercises . Based on the literature, this tension may adversely affect the central nervous system and nerve root function . Accordingly, in the current study ,we will try to answer the question that is it theoretically possible, that increased longitudinal stress and strain on the spinal cord and nerve root from stretching exercises may subtly impair the neural function.in addition to investigate the effect of stretching on other management outcomes;pain intensity,disability,range of motion,and Pressure-pain threshold.
A multitude of stretching parameters are used in the clinical setting. However, there is no convincing evidence to suggest which parameters are most effective in the management of chronic myofascial pain syndrome .In this regard, although the stretching duration is considered one of the most important variables that can affect the treatment outcome, to date there is little agreement on the most effective stretching duration.Accordingly ,we will conduct this study to investigate the effect of different stretching duration on nerve root function ,central conduction time, and chronic myofascial pain management outcomes.