Energetic cost of walking with increased step variability.

Area of Science:

• Biomechanics
• Human locomotion
• Metabolic energy expenditure

Background:

• Human walking involves natural step-by-step variations due to sensorimotor control and perturbations.
• These gait variations may increase energy expenditure by deviating from economical gait and requiring active stabilization.
• Understanding the link between gait variability and energy cost is crucial for studying conditions affecting walking.

Purpose of the Study:

• To investigate the impact of artificially increased step variability on the metabolic energy expenditure during human walking.
• To determine if visual perturbations in a virtual reality environment can effectively induce gait variability and measure its energetic consequences.

Main Methods:

• Healthy young adults (N=11) walked on a treadmill within a virtual reality environment.
• Visual perturbations (fore-aft and medio-lateral) were applied to a virtual hallway to induce step variability.
• Net metabolic rate was measured using indirect calorimetry to assess energy expenditure.

Main Results:

• Medio-lateral visual perturbations significantly increased step width variability (65%) and net metabolic rate (5.9%).
• Perturbations generally increased variability in step width and length, altering mean step dimensions.
• Measures of gait variability and step dimensions correlated significantly with each other and with metabolic rate.

Conclusions:

• Artificially increasing step variability, particularly width, elevates the metabolic cost of walking.
• These findings support the hypothesis that imperfect sensorimotor control contributes to increased energy expenditure during walking.
• The results have implications for understanding the metabolic burden in aging populations and individuals with gait disorders.