Myofascial pain syndromes are prevalent in the commnnity with Chiropractors often managing these conditions in their practices. Myofascial trigger points are the hallmark clinical sign of myofascial pain syndromes and often develop as a secondary condition to other musculoskeletal injuries. Myofascial trigger points can be associated with vertebral subluxation, both of which can contribute to somatic dysfunction.

This study is designed to investigate the effect of latent myofascial trigger points (LTP’s) on the temporal sequence of muscle recruitment in the shoulder girdle during elevation of the arm in the scapular plane. Latent trigger points are asymptomatic, except when being palpated directly, although they can reduce the range of motion of the muscle in which they are located. It has been shown that glenohumeral joint pain is associated with increased variability in the temporal sequence of muscle recruitment of the scapular rotator muscles during elevation of the arm in the scapular plane. However, it is not known whether such altered muscle recruitment patterns cause, or are the result of joint dysfunction.

The aims of this study are as follows:

1. To use electromyography to establish the temporal sequence of muscle recruitment of key shoulder girdle muscles during elevation of the arm in the scapular plane, in normal subjects.

2. To establish the prevalence ofLTP’s in the scapular rotator muscles in asymptomatic subjects.

3. To use electromyography to compare the shoulder girdle muscle recruitment pattern of normal subjects to that of asymptomatic subjects with LTP’s in the scapular rotator muscles, during elevation of the arm in the scapular plane.

4. To investigate what effect removing the LTP’s from the scapular rotator muscles has on the muscle recruitment pattern of key shoulder girdle muscles during elevation of the arm in the scapular plane.

This project has direct clinical relevance as it contributes to an understanding of the anatomical and biomechanical mechanisms underlying chiropractic care. Any differences found in the sequence of muscle recruitment between groups will be present in an asymptomatic environment and so will not be affected by the presence of pain. IfLTP’s in the scapular rotator muscles increases the variability of the muscle recruitment pattern employed to elevate the arm in the plane of the scapula, it may be appropriate for Chiropractors to focus on the removal of LTP’s around the scapula in order to decrease the incidence of recurrent shoulder pain.

Grant Value: $18,184
Chief Investigator: Dr Karen Lucas – RMIT
Status: Complete

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