Is There an Optimal Recovery Step Landing Zone Against Slip-Induced Backward Falls During Walking?

Area of Science:

• Biomechanics
• Gerontology
• Motor Control

Background:

• Recovery stepping is crucial for fall prevention after slips.
• The impact of recovery foot placement on fall likelihood is not well understood.

Purpose of the Study:

• To determine if an optimal recovery landing zone exists for older adults to increase recovery likelihood after a slip.
• To investigate the relationship between recovery step placement and stability/limb support.

Main Methods:

• 195 older adults experienced unannounced forward slips on a 7-m walkway.
• Analysis of center of mass (COM) stability, vertical limb support, and recovery limb joint moments.
• Quantification of relative recovery step placement (distance between foot and COM).

Main Results:

• A longer relative recovery step placement improved stability but reduced limb support, and vice versa.
• Relative recovery step placement predicted recovery likelihood with 67.3% accuracy.
• Recovery rates exceeded 50% when the foot-COM distance was less than 0.3 foot lengths.

Conclusions:

• Recovery step placement significantly influences the success of recovery after a forward slip.
• An optimal range for recovery foot placement likely exists to balance stability and limb support.
• Specific joint moment deficits were associated with both posterior and anterior recovery stepping patterns.