Clinical Outcomes, Viscoelastic Properties and Central Pain Mechanisms After Eccentric Training in Neck/Shoulder Pain

A custom-built dynamic shoulder dynamometer (Aalborg University, Aalborg, Denmark) will be used. Participants will be seated with back support and no feet support. The maximal voluntary contraction (MVC) of the painful side will be assessed. Sessions will start with a 5-min warm-up. After that, participants will sit in the dynamometer, and the range of shoulder elevation (highest and lowest vertical position) will be measured for the affected side. During training, subjects will have to counteract a dynamometer vertical force from the highest to the lowest shoulder position at a force equal to 60% (training sessions 1-3), 70% (training sessions 4-6), and 80% (training sessions 7-10) of the MVC recorded during baseline. Three bouts of 10 repetitions (sessions 1-3), 8 repetitions (sessions 4-6) and 6 repetitions (sessions 7-10) will be performed, with a 3-second rest between contractions and a 2-minute break between bouts.