Comparable neural and behavioural performance in dominant and non-dominant hands during grasping tasks

Hand dominance has long been associated with differences in neural control and motor performance, with the dominant hand typically exhibiting better coordination in reaching tasks. However, the extent to which this dominance influences performance in finger force control remains unclear. This study aimed to examine the behavioural and neural features of the dominant and non-dominant hands during grasping and lifting tasks in healthy young adults, focusing on the synergy index, EEG band power, and EEG-EMG coherence as key measures. Twenty right-handed adults participated in this study. Participants engaged in an experimental task where they grasped a handle for the initial 5 s, followed by lifting and holding it for an additional 5 s. There were two task conditions: fixed (thumb platform secured) and free (thumb platform movable). It was hypothesized that the dominant hand would exhibit greater finger force coordination and enhanced neural features, including higher EEG band power and increased EEG-EMG coherence, compared to the non-dominant hand. Contrary to the hypothesis, we found statistical equivalence in the synergy index, EEG band power, and EEG-EMG coherence between the dominant and non-dominant hands across both fixed and free task conditions. These findings suggest that both hands can achieve similar levels of performance in tasks emphasizing steady-state force maintenance, despite the typical advantages of the dominant hand in other motor tasks. However, a significant difference was observed between task conditions, with the fixed condition showing higher values than the free condition in both behavioural (synergy index-η² = 0.81, p < 0.0001,) and neural (EEG band power η² = 0.37, p < 0.05 and EEG-EMG coherence-η² = 0.49, p < 0.0001) features. These differences were likely due to changes in friction, yet the adjustments remained consistent between the dominant and non-dominant hands.