The dominant limb preferentially stabilizes posture in a bimanual task with physical coupling

Area of Science:

• Neuroscience
• Biomechanics
• Human motor control

Background:

• The dynamic dominance theory suggests the nondominant hand is specialized for postural stability.
• Previous research tested this theory using unimanual tasks or bimanual tasks with differing hand functions.

Purpose of the Study:

• To test the dynamic dominance hypothesis in a bimanual task where both hands perform the same function.
• To investigate hand specialization for stabilization during object manipulation.

Main Methods:

• Utilized a dual-wrist robotic interface to physically couple subjects' wrists.
• Examined wrist flexor and extensor muscle activity in left- and right-handed individuals holding a virtual object.
• Assessed the influence of hand strength and the Edinburgh inventory on stabilization strategies.

Main Results:

• Subjects showed a preference for cocontracting the dominant hand for stabilization during both holding and transport.
• This dominant hand preference for stabilization contradicts the dynamic dominance hypothesis.
• Dominant hand strength partially explained this preference, but handedness (Edinburgh inventory) was a better predictor of cocontraction differences.

Conclusions:

• The dominant limb preferentially utilizes cocontraction to stabilize bimanually held objects.
• Findings challenge the established view that the nondominant limb is specialized for stabilization.
• Handedness and limb strength play crucial roles in bimanual stabilization strategies.