Asymmetrical load-carrying while stepping down a curb in young adults

Area of Science:

• Biomechanics
• Human Movement Science
• Ergonomics

Background:

• Asymmetrical load-carrying alters joint forces and body stability, especially on uneven terrain like curbs.
• Carrying a bag can restrict arm movement, potentially affecting upper limb interlimb coordination and balance.
• Previous research on wrist-worn loads showed no coordination changes, but bag dynamics might induce greater compensatory movements.

Purpose of the Study:

• To investigate how asymmetric load-carrying with different bag types affects upper limb coordination.
• To examine walking adaptations during curb negotiation while carrying a load with dominant and non-dominant hands.
• To determine if upper limb coordination changes impact curb negotiation performance in young adults.

Main Methods:

• Seventeen young adults performed a curb negotiation task carrying a bag equivalent to 7% of their body mass.
• Experimental conditions included walking without a bag and carrying a bag (with/without strap) using either the dominant or non-dominant hand.
• Kinematic data were analyzed to assess upper limb interlimb coordination and foot-curb interaction.

Main Results:

• Load carriage significantly reduced the anti-phase movement pattern of the upper limbs.
• The shoulder on the side carrying the load exhibited increased phase synchronization, indicating reduced movement.
• Despite altered upper limb coordination, key foot-curb negotiation parameters remained unaffected.

Conclusions:

• Mild asymmetric load carriage, particularly with a bag, influences upper limb interlimb coordination.
• Young adults effectively compensated for load-induced disturbances, maintaining stable curb negotiation.
• The study highlights the body's adaptability in managing asymmetric loads during challenging locomotion tasks.