Short-Term Training Improves the Sense of Force in a Hand Muscle

The sense of force can be defined as the awareness of the force produced by the neuromuscular system. Compared with other modalities, sense of force has been less studied, and whether it can be trained remains an open question. This study investigated whether short-term training can improve force sense and whether such gain is force-level specific and transferable to the contralateral untrained limb. The sense of force was assessed in thirteen healthy adults with a force-reproduction task performed with the first dorsal interosseous muscle at 5% and 20% of their maximal force (MVC). The study design involved a 3-week control period followed by a 3-week training program (nine sessions) consisting of performing force-matching tasks at submaximal intensities (from 2.5 to 22.5% MVC). Absolute error (AE) and signed error (SE) were assessed before and after the two periods (control and training). No change was observed after the control period, regardless of the contraction intensity and hand. In contrast, training significantly reduced AE [before: 36 (16)%; after: 19 (14)%, p = 0.002] and SE [before: 35 (20)%; after: 13 (19)%, p = 0.022] at 5% MVC in the trained hand, with a trend for improvement in AE at 20% MVC. No change was observed in the contralateral hand, regardless of the contraction intensity. This study is the first to show that the sense of force is trainable, with improvements mainly confined to low-force conditions and specific to the trained effector. These findings open promising avenues for future research into its application in rehabilitation settings.