The main objective of this study is to evaluate the effectiveness of therapy which will be a combination of Muscle Energy Technique (MET) and Trigger Point Therapy (TPT), performed bilaterally on the upper trapezius muscle in the group of asymptomatic persons with latent trigger point. The study will show whether one-time therapy has an impact on: mobility of the cervical spine, biophysical parameters (muscle tone, stiffness and elasticity) of soft tissues and pressure pain threshold of upper trapezius muscle. An additional goal will be to compare the effectiveness of the three treatments used: combination of MET with TPT, single MET and single TPT.

Research hypotheses:

• The combination of MET with TPT will increase the angular ranges of basic cervical spine movements immediately after the therapy and these effects will persist the second day after the intervention.
• The combination of MET with TPT will increase the elasticity and reduce muscle tone and stiffness in the area of the upper trapezius immediately after the therapy, and these effects will persist the second day after the intervention.
• The combination of MET with TPT will increase the pressure pain threshold of upper trapezius muscle immediately after the therapy, and this effect will persist the second day after the intervention.
• The combination of MET with TPT will be more effective than single MET and single TPT methods.

Muscle Energy Techniques (MET) can be defined as a group of soft tissue manipulation methods. They are a multi-task techniques that can be performed to improve the function of the musculoskeletal system and reduce pain. METs are used by clinicians who treat various myofascial and joint dysfunctions as well as a form of prevention and protection of the musculoskeletal system.

Trigger point therapy (TPT) uses manual techniques such as ischemic compression (IC), positional release (PR), dry needling and soft tissue manipulations [TP1]. Their main purpose is to reduce or eliminate the symptoms generated by myofascial trigger points (TrPs), which are defined as severely irritated areas within the hypertonic muscle fiber band or the fascia itself. Latent TrPs are described as those that do not generate symptoms on their own. However, they can cause refered pain at the time of provocation, i.e. pressure at the place of their occurrence.

In the scientific literature there are no reports on the assessment of the combination of MET with TPT

The randomized study will focus on assessing the effectiveness of 3 different physiotherapeutic interventions. The physiotherapist with 10 years of professional experience will be responsible for performing all diagnostic procedures and therapeutic interventions.

Diagnosis of latent trigger point will be performed on subjects in the supine position. The therapist using a pincer grip will perform palpation in the area of the entire upper trapezius muscle. Testing for the presence of trigger point can be considered positive when it is noted: 1) the presence of a detectable strained band in the muscle, 2) the presence of an excessively sensitive area in the strained muscle band, 3) the response of local vibration caused by compression of the strained band, 4) occurrence of characteristic transferred symptoms (pain radiating to the posterior-lateral side of the neck, and/or mastoid process of the temporal bone, and/or the temporal bone area, and/or the angle of the jaw) as a result of compression of the hypersensitive muscle band. The test will be performed on both sides of this muscle.

The following measurement methods are planned to be used:

1. Electrogoniometry of the cervical spine. A Penny & Giles strain tensometric electrogoniometer will be used. Using this device, the angular values of cervical spine movements will be examined. The SG150 two-plane sensor and the Q110 single-plane sensor will be used. The lower edge of the upper sensor will be attached around the occipital tuberosity, while the upper edge of the lower sensor on the C7 spinous process. The examined person will be in a sitting position. Double-sided tape from Biometrics will be used to stick the electrogoniometer sensors. For the measurements of each movement, the subject will perform 3 repetitions. Then the mean value will be calculated, which will be the result.

2. Myotonometry. In order to examine the biophysical parameters of soft tissues a MyotonPRO will be used.

   Measurements will be made on the upper part of the trapezius muscle at the point located in the middle of the segment between the C7 spinous process and the shoulder angle of the acromion. During measurements, the subject will be lying down.

3. Pressure pain threshold (PPT). The Wagner Instruments Algometer will be used to assess the subjective parameter - pressure pain threshold of first discomfort. The place of measurement will be the point located on the upper trapezius muscle in the middle of the segment between the C7 spinous process and the shoulder angle of the acromion. The subject will be lying down on his back. Pressure from the algometer sensor will be applied from above and perpendicular to the examined muscle. Three measurements will be taken alternately for both sides of the upper trapezius. The mean value will be calculated, which will be the results for the right and left sides of the examined muscle.

The order of measurements will be: 1) myotometry, 2) pressure pain threshold test, 3) cervical spine electrogoniometry.

Participation in the study will be voluntary, free and fully anonymous. The participant will be able to opt out of the study at any stage. All planned therapeutic and measurement methods are non-invasive and safe. They do not threaten the health and life of the respondents.

Inclusion Criteria:

• right-handed people
• amateur practicing symmetrical sports (eg. swimming, running, cycling, gym, roller skates)
• asymptomatic subjects (without pain symptoms of the cervical spine and shoulder girdle)
• occurrence of latent trigger point of the upper trapezius muscle

Exclusion Criteria:

• age above 21 years
• no latent trigger point on the upper trapezius muscle
• pain in the cervical spine or shoulder girdle
• any neurological symptoms in the upper limb
• previous operations in the cervical spine or shoulder girdle
• practicing asymmetrical sports
• professional sports

University IPD sharing platform is under preparation. All data will also be available to researchers via the principal researcher's email (wendt@awf.poznan.pl) or Research Gate website.

Data will be available from June 2020.

Available to all researchers

Participants will not know which research group they will belong to. Each participant will draw a number that will be specific to the given research group. The investigator will also not know which group the participant belongs to (he will only use the participant's number). The outcomes assessor will not know which group is experimental and which are active comparators (they will be marked numerically instead of using a name). The correct course of the study will be supervised by a person who acts as a coordinator.