The association between nocturnal trapezius muscle activity and shoulder and neck pain

Abstract

The study investigated the possible association between nocturnal trapezius muscle activity and shoulder and neck pain. Sixty female subjects participated in the study, 33 were classified as pain-afflicted on the basis of shoulder and neck pain reports for the previous 6 months. Electromyographic (EMG) activity was monitored bilaterally from the trapezius in all recordings. EMG recording of the deltoid, biceps, and hand flexors was included for 26 subjects (17 with pain) to provide a comparative basis for evaluation of the trapezius recordings. There was considerable variation in the amount of muscle activity between subjects; however, some subjects presented a continuous, low-level activity pattern throughout the presumed sleep period. Subjects classified as pain-afflicted had significantly higher activity level and longer duration of trapezius EMG activity than the pain-free subjects. The deltoid had significantly more activity than the trapezius, while the biceps and the hand flexors presented similar activity level and duration as the trapezius. Nocturnal trapezius activity was not associated with pain exacerbation the same night. We suggest nocturnal trapezius muscle activity is a pointer to physiological mechanisms that contribute to some forms of shoulder and neck pain, such as trapezius myalgia, but nocturnal muscle activity may not be casually implicated in the pain-induction process.

Repetitive and Monotonous Work Among Women: Psychophysiological and Subjective Stress Reactions, Muscle Activity and Neck and Shoulder Pain

“…Then, the muscle activity was unchanged in the pain-afflicted workers, but was significantly reduced in pain-free workers (Holte & Westgaard, 2002). This apparent inability to relax the trapezius muscle during leisure time among pain-afflicted workers was also found during sleep in a separate analysis (Mork & Westgaard, 2004). Moreover, a study concerning myofeedback training in individuals with work-related myalgia in the neck and shoulders showed that a reduction in pain was not related to a decreased muscle activity level, however, it was related to an increased ability to relax the muscles (VollenbroekHutten, Hermans, Voerman, Sandsjö & Kadefors, 2006).…”

“…For example, it was recently shown that women with neck and shoulder pain had higher trapezius muscle activity and a more sustained activity pattern during sleep than did pain-free women (Mork & Westgaard, 2004). A speculation made by Mork and Westgaard (2004) is that these findings are related to an increased autonomic arousal during sleep in those with pain. This is interesting, since during sleep individuals are not under immediate psychological stress or aware of stressors in their life, thus suggesting a more complex role of the autonomic nervous system in relation to muscle pain than merely being triggered in a stressful situation when awake.…”

“…This is interesting, since during sleep individuals are not under immediate psychological stress or aware of stressors in their life, thus suggesting a more complex role of the autonomic nervous system in relation to muscle pain than merely being triggered in a stressful situation when awake. The study by Mork and Westgaard (2004) showed no associations between trapezius muscle activity during sleep and perceived pain intensity the same day or exacerbation of pain during the night. In addition, activity in the deltoid muscle (covering the outer part of the shoulder) during sleep was higher than in the trapezius, in both pain-free and pain-afflicted women, although this region is often unaffected by pain.…”

“…Hypothetically, other parallel physiological mechanisms may account for the genesis of muscle pain, whereas low level muscle activity merely is a pointer to these mechanisms (Mork & Westgaard, 2004;. For example, it was recently shown that women with neck and shoulder pain had higher trapezius muscle activity and a more sustained activity pattern during sleep than did pain-free women (Mork & Westgaard, 2004).…”

A Comparative Study in Cervical Muscle Activities during Various Resting Postures Using Electromyography

“…Hansson et al [6] investigated the root mean square (RMS) of EMG data to present the distribution of various activity levels of neck muscles while at rest. Furthermore, some studies have investigated the relationship between nocturnal trapezius muscle relaxation and neck or shoulder pain for both healthy and unhealthy subjects [18][19][20][21][22] . The provided literature review in this field shows a knowledge gap on effects of resting postures and pillow height on people's neck muscles activities and fatigue, and their resting quality.…”