Research ReportFinger tremor can be voluntarily reduced during a tracking task

Introduction. It is a well-known fact that physiological tremor has a deleterious effect on small and precise movements. We recently showed that the amplitude of postural physiological tremor can be voluntarily reduced. Whether this is also applicable to tremor during small movements has not been explored. Objective. This study aims to characterize tremor during movement, assess whether it is possible to reduce tremor amplitude during voluntary movements, and quantify any changes in accuracy that may result from this modulation. Methods. Finger tremor was measured in 12 healthy volunteers using a laser displacement sensor and recorded during (A) a postural physiological tremor condition, (B) a slow target tracking task, and (C) the same tracking task while trying to reduce tremor amplitude. Results. The tremor characteristics such as distribution of power within the power spectrum remained similar during movement when compared to the static postural condition. Tremor amplitude was significantly reduced when participants attempted to do so. However, this reduction was accompanied with a systematic increase in error. Finally, mean error was significantly higher when the target line moved at higher velocity. Discussion. Our results demonstrate that tremor remains present during movement and that its amplitude can be voluntarily modulated. However, attempting to voluntarily reduce the amplitude of that tremor during movement is not an efficient way to improve tracking performance.

Research Highlights►Tremor is present during movement, and its amplitude can be voluntarily modulated. ►Tremor modulation during movement is systematically accompanied by increased error. ►Movement error is significantly higher when target moves at higher velocity.