Differences on lower trapezius pressure pain threshold, muscle strength and muscle thickness in individuals with chronic neck pain and active or latent myofascial triggers points.

Background: Myofascial trigger points (MTrPs) in the lower trapezius have been recognized as an important source of neck pain. This study aims to compare the lower trapezius muscle strength, pressure pain threshold (PPT) and muscle thickness at rest and contraction between participants and painful vs. no-painful side with active and latent MTrPs; and to examine the associations among these variables with pain intensity, duration and disability in patients with neck pain.

Methods: A cross-sectional study was carried out in 64 people with neck pain with active or latent MTrPs (34 Active MTrPs group and 30 Latent MTrPs groups). Muscle strength, pressure pain threshold and muscle thickness at rest and contraction of the lower trapezius was recorded.

Results: No significant differences were found in descriptive data, dominant side, or side of neck pain. However, the Active MTrPs Group had lower pain pressure thresholds (PPT) on the neck pain side compared to the Latent MTrPs Group, indicating greater sensitivity. Muscle thickness and strength showed minor differences between groups. Pain intensity correlated moderately with pain duration and strongly with neck pain disability.

Conclusions: The results of the present study showed differences in PPT on the lower trapezius muscle in active and latent MTrP in neck side pain compared to non-neck side pain. In addition, lower trapezius strength reported differences between the neck side pain compared to non-neck side pain in both active and latent MTrP. Lower trapezius muscle strength showed significant moderate association with muscle thickness at contraction.