The subject performed these contractions while seated, with the forearm supported on a table surface individually adjusted to elbow height. For the trapezius muscles a submaximal reference voluntary electrical activity (RVE) was used for normalisation. The RVE was determined as the mean activity recorded while the subject was seated and abducting both arms to 90° (in the frontal plane) while holding a 1 kg dumbbell fully pronated in each hand for 15 s