The Effect Of Stretching Exercise on Pectoralis Minor Myofascial Latent Trigger Points

Comparison of Effectiveness of Two Different Stretching Exercises Combined With Pressure Release Technique on Latent Trigger Points in The Pectoralis Minor Muscle

This randomised-controlled trial investigates whether a single intervention of manual pressure release combined with stretching exercise has an effect on muscle length, pain perception threshold, and respiratory function in subjects with latent myofascial trigger point in the pectoralis minor muscle or not. First quarter of the participants will receive a single intervention of manual pressure release combined with contract-relax PNF stretching exercise of pectoralis minor muscle, second quarter of the participants will receive a single intervention of manual pressure release combined with Z stretching exercise of pectoralis minor muscle while, only a single intervention of manual pressure release will be applied to third quarter of the participants and final quarter of them will not receive any intervention.

Myofascial trigger points are hyperirritable points located within a taut band of skeletal muscle or fascia, which cause referred pain, local tenderness and autonomic changes when compressed. They are classified as either active myofascial trigger points (ATrPs) or latent myofascial trigger points (LTrPs). ATrPs can be inactivated by different treatment strategies; however, they never fully disappear but rather convert to the latent form. Therefore, the diagnosis and treatment of LTrPs is important. Invasive and noninvasive techniques are available for management of LTrPs. Invasive techniques include trigger point injections and dry needling whereas noninvasive techniques include manual therapy techniques and electrotherapy modalities. Manual therapy techniques for the treatment of myofascial trigger points include joint manipulation, strain/counterstrain, ischemic compression and pressure, massage therapy, myofascial release therapy, muscle energy techniques, point pressure release and transverse friction massage. Additionally, recent studies showed that the myofascial trigger point therapy combined with stretching exercise may be an effective for decreasing the pain level. However, there is insufficient evidence to determine what type stretching exercise is most effective and its immediate effects on muscle length in people with LTrPs. Therefore, the aim of this randomised-controlled trial is to investigate the effect on muscle length, pain perception threshold, and respiratory function after a single intervention of manual pressure release combined with stretching exercise on LTrPs in the pectoralis minor muscle. The sample size and power calculations is performed with the sample size calculator (InStat). The calculations is based on a standard deviation of 0.5 points, the minimal clinically important difference (MCID) for Pectoralis Minor Index of 0.89 points, an alpha level of 0.05, a β level of 5%, and a desired power of 95%. These parameters generate a sample size of at least 9 participants for each group. Total of 40 subjects will be recruited into the study in order to allow for a loss to follow-up. Potential participants will be invited through the posting of flyers at Istanbul University, Turkey. Flyer recruitment method will be used in this trial because it is the most effective, yielding the highest number of enrolments. All participants will be completed an informed consent form that described the purpose and procedures of testing. prior to participating in the study. Forty participants fitting the inclusion criteria will be randomly assigned to one of four parallel groups (ratio 1:1:1:1). For allocation of the participants, "Randomization.com" which is an online, randomisation web service will be used (http://www.randomization.com/). Simple randomisation procedures (computerized random numbers) will be done and sequentially numbered index cards with the random assignment will be prepared by an investigator with no clinical involvement in the study. The index cards will be folded and placed in sealed opaque envelopes. Then, the blind investigator will open each envelope and allocate the participants to group according to selected index card. The interventions will be performed by the same physiotherapist at a university research clinic, and assessments and data collection will be made by another therapist. Whereas interventionist will be aware of the allocated arm, patients and outcome assessor will be kept blind to allocation. The data will be evaluated using the Statistical Package for the Social Sciences 21.0 program for Windows and by analyzing descriptive statistics (frequency, mean and standard deviation). Kolmogorov-Smirnov Test will be used to assess the distribution of data. The one-way analysis of variance (ANOVA) for repeated measures with the Bonferroni post hoc test will used to determine whether differences in the mean scores of outcome measure among three time points (baseline, immediate after and 24 hours later) between study groups. In this study, p values less than 0.05 will be regarded as statistically significant.

Pain Threshold, Pectoralis Minor, Proprioceptive Neuromuscular Facilitation (PNF) Stretching, Physiotherapy, Rehabilitation

A contract-relax PNF stretching techniques of the pectoralis minor muscle including latent trigger points will be applied by Group 1 after a single intervention of manual pressure release will be performed according to the techniques describe by Simons et al. (1999).

The Z- stretch of the pectoralis minor muscle including latent trigger points will be applied by Group 2 after a single intervention of manual pressure release will be performed according to the techniques describe by Simons et al. (1999).

The single intervention of manual pressure release will be only applied to Group 3 according to the techniques describe by Simons et al. (1999).

Subjects will be positioned supine on a treatment plinth and will be encouraged to relax as much as possible before pressure is applied. A slow pressure to myofascial latent trigger point will be applied directly over the marked pectoralis minor muscle myofascial latent trigger point site until a moderate but tolerable pain value of 7 out of 10 (0= no pain, 10= severe pain) is reported. Constant pressure will be sustained for 90 seconds if the subjects report that the pain is decreased to a value of 3, the pressure will be increased to restore perceived pain to the value of 7. Then, tissue resistance (barrier) in pectoralis minor muscle will be controlled.

Subjects will be in a sitting position with hands being clasped behind the head. The pectoralis minor muscle will be passively and slowly stretched until a strong but tolerable stretch discomfort intensity level of 4 out of 10 (0= no pain, 10= severe pain) is reported. Passive stretch will be sustained for 10 seconds followed by 6 seconds of maximal voluntary isometric contraction of the pectoralis minor muscle. Then, subjects will be instructed to relax for further 4 seconds. Subjects will maintain newly active stretched position of pectoralis minor muscle for 10 seconds with a strong but tolerable stretch discomfort intensity level of 4 out of 10. The procedure will be repeated four times with 30 seconds of rest between two successive trials.

Subjects will be positioned supine with knee bent on a treatment plinth, and the legs will be rotated to the opposite direction of the arm to be stretched placing a stabilizing distal tension on the ribs. Then, the subjects will be slowly brought the arm in a circular motion overhead pausing at the points of tightness, maintaining close contact to the treatment table until a strong but tolerable stretch discomfort intensity level of 4 out of 10 (0= no pain, 10= severe pain) is reported. Self-stretch of pectoralis minor muscle, including myofascial latent trigger points will be sustained for 30 seconds. The procedure will be repeated four times with 30 seconds of rest between two successive trials.

The PMI will be calculated by dividing the resting muscle length measurement by the subject height in centimeters and multiplying by 100. The test-retest reliability for PMI measurement is 0.94 (95 % Confidence Interval (CI): 0.81-0.98).

The resting length of the pectoralis minor can be validly measured using palpable landmarks and can be reliably measured with a caliper or a cloth tape measure. These landmarks are (1) the inferomedial aspect of the coracoid process and (2) the caudal edge of the fourth rib at the sternum. The distance in centimeters between these bony reference points will be measured with using a tape measure.

Digital pressure algometry showed high intra-rater reliability for pressure pain threshold measurements which might be a useful parameter in assessing the effects of treatment for musculoskeletal pain and myofascial pain syndrome.

There is no significant difference between the concurrent validity of the supine rounded shoulder posture measure an a seated assessment of scapular posture. Rounded shoulder posture will be measured from the acromion to the wall behind the subject to determine the amount of forward displacement with using a levelled metric ruler

Maximum Inspiratory Pressure (MIP) will be assessed by using a hand-held respiratory pressure meter (cmH2O).

Maximal Expiratory Pressure (MEP) will be assessed by using a hand-held respiratory pressure meter (cmH2O).

The VAS is used for which a patient is asked to indicate his/her perceived pain during the rest and activity times. Respondents will mark the location on the 10-centimeter (cm) line corresponding to the amount of pain they experienced.

The DASH questionnaire is a region-specific, self-report scale to evaluate health status of upper extremity disabilities.

The Short-Form 12 questionnaire is an instrument for evaluating health and quality of life perception.

Inclusion Criteria: Subjects diagnosed with at least one latent myofascial trigger point in the pectoralis minor muscle Exclusion Criteria: Presence of active trigger points in the pectoralis minor muscle Any orthopaedic problems pertaining to the spine-shoulder complex (e.g., fractures, arthrosis, listhesis, sprains, strains) within the last six months Surgery on the spine-shoulder complex before the study Neurological impairment in the upper extremities Receiving the treatment for myofascial pain within the last three months Receiving anti-inflammatory and pain relief medication in the past 24 hours

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