EMG Activity, Muscle Tone, Elasticity and Stiffness of the Upper Trapezius Before, During and After Dry Needling

Brief Summary

Detailed Description

Neck-shoulder pain is a frequent problem in office workers . These complaints are often related to myofascial problems of neck and shoulder muscles in which the upper trapezius is frequently involved. Trapezius myalgia (TM) is characterized by pain, palpable stiffness and tenderness of the upper part of the trapezius muscle. Several studies show that myofascial trigger points (MTrP) have an important role in the development and maintenance of myofascial pain. Trigger points are defined as hyperirritable nodules in a contracture of skeletal muscle fibers. The pathophysiology of MTrPs is still unclear but several hypothesis exist. The most plausible explanation is that, due to sustained postures or repetitive low-level tasks, a sustained irritation of motor end plates with an excessive release of acetylcholine arises. This may lead to a persistent sarcomere contraction, leading to an impaired blood circulation, a reduced oxygenation and energy depletion, sensitizing nociceptors and causing pain. Dry needling (DN) is a myofascial treatment technique, in which a thin, solid filiform needle is inserted directly into the MTrP. During dry needling, local twitch responses (LTR) can be elicited. These are involuntary contractions of muscle fibers, leading to muscle relaxation, an increase in blood flow, recovery of the muscle metabolism and thus a reduction of pain and stiffness. In this experimental study, 25 female office workers with trapezius myalgia are recruited from several work places with predominantly computer based tasks. These subjects have to perform at least 20 hours a week of computer work and this since at least one year. Subjects are included based on online questionnaires, a clinical examination of neck an shoulder and the presence of MTRP 2 in the upper trapezius. All participants will receive information and have to sign an informed consent form. Participants will be subjected to baseline assessment which involves measuring resting surface EMG activity, muscle tone, stiffness, elasticity and pain. Then, subjects have to perform a computer task during 20 minutes while surface EMG activity will be measured every 5 minutes. After this computer task, all measurements will be repeated. After a resting period of 10 minutes, baseline measurements are repeated, followed by a computer task of 20 minutes and repetition of the same assessment. After this computer task, a single dry needling session of MTrP 2 of the upper trapezius will be performed bilaterally. During this treatment, surface EMG activity will be measured to captivate the EMG activity during local twitch responses. This is followed by repeating the same measurements 1 and 10 minutes after dry needling.

Primary Outcomes

Secondary Outcomes

• Changes in surface resting EMG activity of the upper trapezius after rest as assessed by the EMG DTS device(Immediately after a typing task of 20 minutes, immediately after a resting pause of 10 minutes)
• Changes in muscle tone, stiffness and elasticity of the upper trapezius after dry needling as assessed by the MyotonPRO ®(Immediately after a typing task of 20 minutes, one minute after dry needling, 10 minutes after dry needling)
• Changes in muscle tone, stiffness and elasticity of the upper trapezius after rest as assessed by the MyotonPRO ®(Immediately after a typing task of 20 minutes, immediately after 10 minutes of rest)
• Changes in muscle tone, stiffness and elasticity of the upper trapezius after a typing task, compared to baseline, as assessed by the MyotonPRO ®(Before and immediately after a typing task of 20 minutes)
• Changes in pain score after a typing task of 20 minutes as assessed by the numeric rating scale(Immediately before and after a typing task of 20 minutes)
• Changes in surface resting EMG activity of the upper trapezius during a fatiguing typing task of 20 minutes as assessed by the EMG DTS device(During the typing task, every five minutes EMG activity will be measured for 30 seconds)
• Differences in active muscle tension of the upper trapezius (ratio between resting EMG activity in upright and lying position) between the (dominant) painful and heterolateral side, as assessed by the EMG DTS device(At baseline)
• Changes in pain score after rest as assessed by the numeric rating scale(Immediately after a typing task of 20 minutes, immediately after 10 minutes of rest)
• Differences in muscle fatigue of the upper trapezius (ratio between resting EMG activity before and after a typing task of 20 minutes) between the (dominant) painful and heterolateral side, as assessed by the EMG DTS device(Before and after a typing task of 20 minutes)
• Differences in muscle tone, stiffness and elasticity of the upper trapezius between the (dominant) painful and heterolateral side, as assessed by the MyotonPRO ®(At baseline)
• Changes in pain score after dry needling as assessed by the numeric rating scale(Immediately after a typing task of 20 minutes, one minute after dry needling, 10 minutes after dry needling)
• Differences in pain score at baseline between the (dominant) painful side and heterolateral side(At baseline)