Perturbation-based estimation of within-stride cycle metabolic cost

Area of Science:

• Biomechanics
• Human Movement Analysis
• Metabolic Physiology

Background:

• Metabolic cost is a critical factor in human movement.
• Current methods for measuring metabolic cost provide only average values per movement cycle.
• This limits the understanding of energy expenditure during specific phases of locomotion, such as walking.

Purpose of the Study:

• To develop and validate a novel method for estimating the within-stride metabolic cost of walking.
• To differentiate the energy expenditure across different phases of the walking cycle.
• To identify the most metabolically costly phases during walking.

Main Methods:

• Utilized measurements from varying force perturbations during walking.
• Developed a novel method to estimate the metabolic cost within individual strides.
• Compared the accuracy of this perturbation-based method against previous model-based estimations.

Main Results:

• The perturbation-based method demonstrated higher consistency in reproducing time series data (r = 0.55 and 0.80) compared to prior models (r = 0.29).
• Revealed that the metabolic cost of the push-off phase is significantly lower (10%) than predicted by positive mechanical work (~70%).
• Identified specific phases of the walking cycle that contribute most to overall metabolic cost.

Conclusions:

• The developed perturbation-based method accurately estimates within-stride metabolic cost during walking.
• This approach provides a more granular understanding of energy expenditure during locomotion.
• Findings offer new targets for optimizing assistive devices and informing rehabilitation strategies for walking.