Could task performance be constrained by our ability to fully engage necessary neural processing through effort of will? The StartReact phenomenon suggests that this might be the case, as voluntary reaction times are substantially reduced by loud sounds. Here, we show that loud auditory stimulation can also be associated with an improvement in the force and speed of force development when 18 healthy subjects are repeatedly asked to make a maximal grip as fast and as strongly as possible. Peak grip force was increased by 7.2 ± 1.4% (SEM) (P < 0.0001), and the rate of force development was increased by 17.6 ± 2.0% (P < 0.00001), when imperative visual cues were accompanied by a loud auditory stimulus rather than delivered alone. This implies that loud auditory stimuli may allow motor pathways to be optimised beyond what can be achieved by effort of will alone.