Deeney C, et al. - The effects of quantitative levels of cognitive loading were investigated on the conduction velocity changes and isometric endurance times for the upper trapezius. In comparison with the performance of an equivalent exertion with the low cognitive load, performing a high-difficulty cognitive task while simultaneously performing increasingly higher levels of static isometric shoulder abduction exertions, fatigued the trapezius muscle quicker. This was particularly relevant to workplaces with increasing levels of automation that required high levels of decision making and computer use.