Muscle activation characteristics associated with differences in physiological tremor amplitude between the dominant and non-dominant hand

The aim of this study was to assess differences in physiological tremor amplitude of the hand between the dominant and non-dominant side of right-handed individuals. Mechanical loading of the hand and frequency analysis were used in an attempt to identify the physiological mechanisms involved in observed differences. Seventeen healthy right-handed adults participated in a single session where physiological tremor of the outstretched left and right hands was recorded under different loading conditions (0 g up to 5614 g). Physiological tremor amplitude was quantified through accelerometry and electromyographic (EMG) signals of wrist extensor and flexor muscles were also recorded. The main findings were: ∼30% greater amplitude of fluctuations in acceleration for the non-dominant compared with the dominant hand, no difference in the frequency content of acceleration or demodulated EMG signals between dominant and non-dominant sides across all loads, and condition-dependent associations between the amplitude of fluctuations in acceleration and EMG amplitude and frequency content. These associations suggest a potential role of central modulation of neural activity to explain dominance-related differences in physiological tremor amplitude of the hand.