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.

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.

Inclusion Criteria:

• Consecutive patients will be included if they have active, palpable Myofascial trigger points on a single side or both sides of the upper trapezius muscle. Diagnosis was made according to Simons criteria, which includes five major and three minor criteria. For inclusion, cervical myofascial pain syndrome will be diagnosed with all five major criteria and at least one minor criterion.

Major criteria:

1. Regional pain complaint in the neck.
2. Pain complaint or altered sensation in the expected distribution of referred pain from a myofascial trigger point.
3. Taut band palpable in an accessible muscle.
4. Excruciating spot tenderness at one point along the length of the taut band.
5. Some degree of restricted range of motion , when measurable.

Minor criteria:

1. Reproduction of clinical pain complaint, or altered sensation, by pressure on the tender spot.
2. Elicitation of a local twitch response by transverse snapping palpation at the tender spot or by needle insertion into the tender spot in the taut band.
3. Pain alleviated by elongating (stretching) the muscle or by injecting the tender spot (trigger point).

Exclusion Criteria:

Participants will be excluded if any signs or symptoms of medical "red flags" were present: tumor, fracture, rheumatoid arthritis, osteoporosis, and prolonged steroid use. Additionally, subjects will be excluded with previous spine surgery and any exam findings consistent with neurological diseases and vascular disorders.

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There is a plan to make individual participant data and related data dictionaries available

After 6 months and will become available for one year

not identified yet

The treating therapist, for both the control and intervention groups, was unblinded to the treatment method but the subjects and assessor who conducted the measurements were blinded. Assessor blinding was obtained through an independent research assist; not knowing the study design and not specifically involved in any aspect of the trial