Effects of Kinesio Taping on Pain, Pressure Pain Threshold, Trapezius Muscle Thickness, and Strain Elastography in Patients With Upper Trapezius Myofascial Trigger Points: A Randomized Sham-Controlled Trial

Myofascial pain syndrome is characterized by hyperirritable nodules located within taut bands of skeletal muscle, known as myofascial trigger points. The upper trapezius is the most commonly involved muscle in the neck and shoulder girdle, and trigger points in this region are an important cause of neck pain, restricted mobility and loss of productivity.

Kinesio taping has become increasingly popular in the management of myofascial trigger points because it is non-invasive, painless, inexpensive and has few adverse effects. Systematic reviews and meta-analyses suggest that kinesio taping reduces pain intensity and improves pressure pain threshold and range of motion in myofascial pain syndrome. However, the taping techniques used across studies differ substantially. Two techniques predominate: the space correction technique, in which strips are applied over the trigger point in a star-shaped pattern, and the muscle inhibition technique, in which a single I-strip is applied along the muscle fibres from insertion to origin with low tension. A trial directly comparing these two techniques found no significant difference between them, whereas a sham-controlled trial found that the space correction technique was not superior to sham at 72 hours. Studies using the inhibition technique have reported significant improvements in pressure pain threshold. Because the inhibition technique is mechanistically aimed at reducing muscle tone and is supported by stronger evidence, it was selected for this trial.

In addition, outcome measures in previous studies have been largely subjective. Pressure algometry provides a quantitative measure of the mechanical sensitivity of the trigger point, while B-mode ultrasonography allows measurement of muscle thickness and ultrasound elastography allows objective assessment of tissue stiffness. Strain elastography with calculation of the strain ratio has shown good reliability in patients with upper trapezius myofascial pain syndrome and can differentiate active trigger points, latent trigger points and control sites.

To the best of our knowledge, no sham-controlled randomized trial has evaluated kinesio taping of upper trapezius myofascial trigger points using pressure pain threshold as the primary outcome together with muscle thickness and strain elastography as objective secondary outcomes. A sham-controlled design was chosen because sham taping alone may produce a substantial placebo response, and only a sham comparator can isolate the true therapeutic effect.

In the intervention group, a single I-shaped kinesio tape strip will be applied from insertion to origin along the upper trapezius with 15-25% tension while the muscle is held in a stretched position. In the sham group, an identical tape of the same brand, colour and size will be applied to the same region without therapeutic tension and with the neck in a neutral position, so that the skin convolutions responsible for the therapeutic effect are not produced. Both groups will receive four applications over two weeks (twice weekly); at each session the existing tape is removed and a new tape applied, so the tape remains on the skin continuously throughout the treatment period.