## Materials and Methods  
### Study Design and Subjects  
This study was conducted over three separate days that were interspaced with at least three days with no exercises. On the first day participants were familiarized with the elastic band training exercises and practiced the proper technique under supervision. On the second day, individual loadings were determined for each training exercise during low intensity, high repetition sets (20 RM), and during high intensity, moderate repetition sets (12 RM). All of the exercises were performed while using concentric and eeccentric muscle contractions in a controlled manner, with slow to moderate lifting velocity corresponding to the execution in earlier intervention studies [16]. Subsequently, the actual duration of concentric and eccentric phases were measured and shown to have an equal duaration each of minimum three seconds. The length and color code of elastic bands were adjusted to reduce or increase the resistance to match 12 RM and 20 RM for each participant. The task was repeated until the participant was exhausted and/or not able to continue the exercise according to the basics of procedures in the literature to define the individual 12 RM and 20 RM loads for each exercise [15]. The participant was deemed not able to continue the exercise if making compensating adjustment in body posture or not obeying contraction time and range of movement. The exercise was repeated until the loading corresponding to 20 RM and 12 RM was determined. On the third day, the determined loadings for each participant were applied and all EMG measurements were performed, while the participant performed all exercises at the intensity of 20 RM sets, followed by 12 RM sets. The order of exercises was randomized and each exercise was separated by 3-minutes rest intervals to avoid a gradient of fatigue through the test protocol. At the end, isometric maximal voluntary contractions (MVC) were performed for the normalization of the EMG data. For each targeted muscle, three MVCs with a duration of 5 s and 1 minute rest between consecutive trials were performed to induce the maximal muscle activity in a seated position and according to standardized procedures described in details in a recent study [23]. In short, maximal activity in mUTR was obtained during resisted bilateral shoulder elevation, with resistance being placed above the acromions. Maximal activity for mUNE was obtained during a resisted cervical extension and for mSCM during a resisted cervical flexion with resistance being placed on the external occipital protuberance and above the eyebrows, respectively.  
The subjects participating were a group of 11 healthy males (age \(25.9\pm 1.4\) years, height 183.6 \(\pm\) 5.0 cm, body mass 82.1 \(\pm\) 6.0 kg, BMI \(24.3\pm 1.4\)), with no pain in neck or shoulders (VAS = 0). The inclusion of only males was justified by the aviation personell--who used these exercises in a previous RCT study--all being males [8]. All of the subjects were informed regarding the benefits and risks of the investigation prior to signing the institutionally approved consent document to participate in the study. The local Ethics Committee of Southern Denmark (S-20120121) approved the procedures in the study.