Increasing step width reduces the requirements for subtalar joint moments and powers

Area of Science:

• Biomechanics
• Human Locomotion
• Musculoskeletal Health

Background:

• The subtalar joint (STJ) is crucial for energy absorption and frontal plane stability during walking.
• Observational studies suggest a link between step width and STJ supination moments.

Purpose of the Study:

• To test if increasing step width reduces STJ moments, energy absorption, and power generation.
• To investigate if increased step width shifts energy absorption to proximal joints like the hip.

Main Methods:

• Twelve participants walked on an instrumented treadmill at various fixed step widths (0.1-0.4 leg length).
• Subtalar joint moments, work, and proximal joint mechanics were analyzed at different step widths.

Main Results:

• Wider step widths significantly reduced peak STJ moments during initial contact and propulsion.
• A 43% reduction in STJ energy absorption (negative work) and 30% decrease in positive work were observed with increased step width.
• Increased energy absorption was noted at the hip and knee during initial contact.

Conclusions:

• Increasing step width decreases subtalar joint loading, suggesting a potential benefit for preventing and treating STJ injuries.
• The increased mechanical cost at the hip and knee due to wider steps is considered minor and acceptable for rehabilitation.