Effects of transcranial direct current stimulation during short–term immobilization on motor learning and hand dexterity in healthy adults

Short-term immobilization (STI) alters cortical excitability and impairs motor performance. However, its impact on motor learning and hand dexterity remains unclear. Transcranial direct current stimulation (tDCS) has shown promise for enhancing motor learning and hand dexterity, but whether it can mitigate the adverse effects of immobilization is still uncertain. This study aimed to investigate the effects of STI on motor learning and hand dexterity, and to determine whether anodal tDCS can alleviate the detrimental impact of STI. Sixty healthy adults were randomly assigned to one of three groups: (1) Control (CON), who received neither STI nor tDCS; (2) STI + tDCS; and (3) STI + sham tDCS (tDCS sham ). The right hand was immobilized for 16 h. A single 20-min anodal tDCS session was applied over the left primary motor cortex (M1) before the end of STI. General motor performance can be defined as the overall capacity to execute movement tasks, encompassing both speed and accuracy aspects of motor output. The Sequence Reaction Time Task (SRTT) was used to assess motor learning and general motor performance, and the Purdue Pegboard task (PPT) was used to assess hand dexterity. The PPT consists of the right-hand test and the assemble test (which required the cooperation of both hands). Assessments were conducted at T 0 (before the intervention) and T 1 (immediately after the intervention). STI reduced hand dexterity, but it did not significantly impair general motor performance and selective motor sequence learning. Regarding PPT at T 1 , the STI + tDCS sham group showed lower right-hand ( p = 0.011) and assemble ( p = 0.034) task scores compared to the CON group. Notably, the results also indicate that tDCS alleviated the effects of STI on hand dexterity and improved general motor performance and motor learning. At T 1 , the STI + tDCS group showed significantly higher motor learning ( p = 0.014), right hand ( p = 0.039) and assemble ( p = 0.032) task scores of PPT compared to the STI + tDCS sham group. This study demonstrates that short-term limb immobilization impairs hand dexterity, but does not significantly affect general motor performance and motor learning. Applying anodal tDCS during immobilization limited the decline in performance and even enhanced motor learning. These findings suggest that tDCS may serve as an effective early intervention to preserve motor function and hand dexterity during limb immobilization. Clinical Trial Registration No NCT07089056. Registered on 08 July, 2025.