Effort matching between arms depends on relative limb geometry and personal control

Area of Science:

• Neuroscience
• Motor Control
• Human Physiology

Background:

• Proprioception is the sense of limb position, movement, and motor effort.
• Historically, effort sense is linked to central motor commands for voluntary actions.

Purpose of the Study:

• Investigate how limb geometry and personal control affect the sense of effort.
• Determine if limb position differences influence perceived effort matching between arms.

Main Methods:

• Subjects exerted torques to match opposing limb torques applied by an exoskeleton.
• Experiments varied limb positions (15° and 30° differences) and personal control (self-selection).

Main Results:

• Matching torque was greater with congruent limb positions compared to incongruent ones.
• Subjects overestimated reference arm torque, especially with larger angular differences.
• Self-selecting reference torque significantly reduced perceived effort overestimation.

Conclusions:

• Perceived effort is influenced by limb geometry and the degree of personal control over motor output.
• Loss of personal control during actions increases perceived effort.