Mind your step: metabolic energy cost while walking an enforced gait pattern

Area of Science:

• Biomechanics
• Human locomotion
• Energy expenditure

Background:

• The total energy cost of walking comprises components from the walking movement itself and balance control.
• Differentiating these components is crucial for understanding locomotion efficiency.

Purpose of the Study:

• To investigate the energy cost of walking by enforcing a step pattern, thereby perturbing balance while preserving the walking movement.
• To differentiate the energetic contributions of walking mechanics and balance control.

Main Methods:

• Nine healthy subjects walked on an instrumented treadmill under three conditions: unconstrained walking, following a periodic step pattern, and following a variable step pattern.
• Metabolic energy cost was measured, and center of pressure (CoP) profiles were analyzed to assess task performance and balance control strategies.

Main Results:

• Metabolic energy cost was significantly higher in the periodic (8%) and variable (13%) enforced step trials compared to unconstrained walking.
• Increased variation in CoP trajectories during single limb support indicated a more active ankle strategy in enforced trials.
• Higher metabolic costs may stem from increased preparatory muscle activation and enhanced ankle strategy for lateral balance.

Conclusions:

• Metabolic energy cost of walking is significantly influenced by balance control strategies, even when global gait characteristics remain unchanged.
• Enforcing step patterns increases energy expenditure, highlighting the role of active balance control in walking efficiency.
• The study provides insights into how altered control strategies impact the energetic demands of human locomotion.