Changes in trunk displacement and ground reaction force during right-left hand-behind-back movement

Area of Science:

• Biomechanics
• Human Movement Analysis

Background:

• Hand-behind-back (HBB) movements are common in daily activities and physical therapy.
• Understanding the biomechanics of HBB movements is crucial for injury prevention and rehabilitation.

Purpose of the Study:

• To compare trunk displacement and ground reaction forces during HBB movements using the right and left hands.
• To identify potential asymmetries in HBB movement biomechanics.

Main Methods:

• Twenty healthy right-handed men performed HBB movements while standing.
• Three-dimensional motion capture and force plates were used to measure trunk displacement and ground reaction forces.
• Data were analyzed to compare right and left hand HBB movements.

Main Results:

• Anterior trunk displacement was observed as the thumb reached the pelvis during HBB movements.
• Ground reaction forces on the HBB side increased initially and then decreased as the hand reached the thoracic spine.
• No significant differences in trunk displacement or ground reaction forces were found between right and left hand HBB movements.

Conclusions:

• HBB movements elicit anterior trunk displacement and changes in ground reaction forces bilaterally.
• The biomechanics of HBB movements appear symmetrical between the right and left hands in healthy individuals.
• Clinical assessments of HBB movements should consider trunk displacement and lower extremity loading, particularly on the side of the movement.