Head stabilization during various locomotor tasks in humans. I. Normal subjects

Area of Science:

• Biomechanics
• Human Locomotion
• Postural Control

Background:

• Head stabilization is vital for maintaining balance and visual-motor coordination during movement.
• Understanding head kinematics during locomotion informs the study of postural control systems.

Purpose of the Study:

• To analyze head kinematics, specifically vertical translation and sagittal rotation, during various locomotor tasks.
• To investigate the stabilization of the Frankfort plane (F-P) relative to the earth's horizontal during locomotion.
• To explore the role of head stabilization in postural control and inertial guidance.

Main Methods:

• Ten subjects performed four locomotor tasks: free walking, walking in place, running in place, and hopping.
• A 3D video system reconstructed body motion, focusing on head translation and rotation.
• The Frankfort plane (F-P), approximating the horizontal semi-circular canals, was analyzed for displacement and rotation.

Main Results:

• Head translation amplitude ranged from 1-25 cm and velocities from 0.15-1.8 m/s across tasks.
• The Frankfort plane (F-P) demonstrated significant stabilization around the earth horizontal, with maximum rotation under 20 degrees.
• Head angular velocities were below 140 degrees/s, and predominant frequencies for translation and rotation were 0.4-3.5 Hz.
• Head stabilization compensates for head translation, forming a basis for inertial guidance.

Conclusions:

• The head exhibits significant stabilization during diverse locomotor activities, maintaining the Frankfort plane near horizontal.
• Head stabilization is an integral component of the human postural control system.
• This stabilization mechanism provides a foundation for effective inertial guidance during locomotion.