*2.3. Data Collection: Maximal Voluntary Contraction (MVC) Measurement*

To normalize the EMG data, *MVC* was measured according to the guidelines of the SENIAM protocol [11,21]. All *MVC* measurements were performed while sitting on a dentist's chair and supporting the lower back on the backrest. When measuring the *MVC* of the arm muscles, the forearm was supported on a desk and the elbow was bent at 90◦ . The EDC was measured by providing the maximum resistance force when opening the back of the hand and fingers, and the FDS measured the force to maximally close the fingers and palms using a grip force meter. The SCM was measured while providing the maximum resistance to the left and right rotations of the head with both arms lowered. The shoulder muscle (T) was measured by providing the maximum resistance force when trying to lift the shoulder upward. Each muscle was assessed three times at 5 s intervals, and the highest value was defined as the *MVC*.
