Bimanual force coordination using the vector coding approach: Quantifying coordination quantity and quality

This study aimed to investigate bimanual force coordination in 36 healthy young adults employing a vector coding method. The participants performed bimanual force control at two targeted force levels (i.e., 10 % and 40 % of maximum voluntary contraction [MVC]) and the Purdue Pegboard Test. Force accuracy was used to assess bimanual force control performance. Vector coding analysis was conducted to estimate the quantity and quality of bimanual force coordination. Further, the correlation between bimanual force coordination and bimanual dexterity was investigated. Lower force accuracy was observed at 40 % of MVC. The coordination quantity analysis revealed that left- and right-hand phases were more frequently observed at 10 % of MVC, whereas the greatest quantity of in-phase coordination was observed at 40 % of MVC. Notably, anti-phase coordination demonstrated higher quality in error correction despite its lower quantity. Moreover, a greater quantity of anti-phase coordination at 40 % of MVC was associated with superior bimanual dexterity. These results indicated that quantifying the quantity and quality of coordination using the vector coding method provides a novel framework for identifying specific motor control strategies during bimanual tasks.