A pelvis-oriented margin of stability is robust against deviations in walking direction.

Area of Science:

• Biomechanics
• Human locomotion
• Gait analysis

Background:

• The Margin of Stability (MOS) is crucial for assessing walking stability, typically measured against a linear path.
• Distinguishing lateral and anteroposterior MOS becomes difficult during irregular directional changes in daily activities.
• Existing methods may not accurately reflect stability during complex, non-linear movements.

Purpose of the Study:

• To evaluate an anatomically oriented MOS calculation using pelvic orientation to define directional stability.
• To test the hypothesis that a pelvis-oriented MOS measure exhibits less variability than a global MOS measure during curved walking.
• To determine the robustness of pelvis-oriented MOS during deviations from a straight walking path.

Main Methods:

• Recruited 16 participants to walk on straight and curved paths at preferred and fast speeds.
• Calculated anterior MOS at mid-swing and posterior/lateral MOS at foot strike using both global and pelvis-oriented models.
• Employed repeated measures factorial ANOVAs to analyze the effects of model, limb, and speed on MOS values.

Main Results:

• The pelvis-oriented MOS demonstrated reduced variability during curved walking, indicating greater robustness to deviations.
• Compared to the global model, the pelvis-oriented MOS showed less lateral and more anterior stability during straight walking.
• These stability differences were amplified at faster walking speeds.

Conclusions:

• The pelvis-oriented MOS is a more robust measure of stability during unpredictable or curved walking paths.
• This method provides valuable insights into gait dynamics when the intended path of progression is unclear.
• The findings suggest clinical utility for assessing stability in real-world, dynamic environments.