Characterizing the balance-dexterity task as a concurrent bipedal task to investigate trunk control during dynamic...

Area of Science:

• Biomechanics
• Motor Control
• Human Movement Science

Background:

• Dynamic balance relies on integrated lower-extremity and trunk control.
• Existing tasks often isolate single aspects of balance or dexterity.
• A need exists for tasks evaluating concurrent bipedal and trunk responses during dynamic balance.

Purpose of the Study:

• To characterize the novel Balance-Dexterity Task for investigating concurrent bipedal lower-extremity control and trunk stability during dynamic balance.
• To assess the task's ability to measure both limb-specific balance and dexterous force control.
• To evaluate trunk control during the task using kinematic and electromyographic measures.

Main Methods:

• Nineteen non-disabled participants performed the Balance-Dexterity Task, involving single-limb stance and contralateral limb force compression.
• Performance measures included limb balance, force control variability, and trunk kinematics (center of pressure, trunk coupling).
• Electromyography was used to assess trunk muscle activity.

Main Results:

• Participants achieved target forces between 100-139 N (14.4-23.0% body weight).
• Greater variability in force control was associated with increased center of pressure (COP) resultant velocity (R=0.598, p=0.007).
• Trunk coupling (R² of thorax/pelvis angles) varied independently of balance or force control measures.

Conclusions:

• The Balance-Dexterity Task effectively measures concurrent bipedal coordination and trunk control during dynamic balance.
• Force control variability is linked to postural sway, indicating its relevance in dynamic balance.
• Trunk coupling appears to be controlled independently of lower-extremity balance and dexterity demands in this task.