Development of a Cadence-based Metabolic Equation for Walking

Area of Science:

• Exercise Physiology
• Biomechanics

Background:

• Assessing walking intensity is crucial for exercise prescription and public health.
• Current methods like the American College of Sports Medicine (ACSM) metabolic equation rely on speed and grade, which are less practical for overground ambulation.
• There is a need for more accessible and accurate methods to quantify walking intensity during free-living activities.

Purpose of the Study:

• To develop and validate cadence-based metabolic equations (CME) for predicting walking intensity.
• To compare the predictive accuracy of these new CME against the established ACSM metabolic equation.

Main Methods:

• Two hundred thirty-five adults walked on a treadmill at various speeds (0.22–2.24 m/s).
• Oxygen uptake (intensity) was measured via indirect calorimetry, and cadence (steps/min) was recorded.
• Simple and full CME were developed using regression analysis, and predictive accuracy was assessed using k-fold cross-validation.

Main Results:

• The simple CME predicted intensity with minimal bias (~0.5 METs) at normal walking speeds.
• Both CME demonstrated significantly greater accuracy (23–35%) and lower bias (0.6–0.8 METs) compared to the ACSM equation.
• The full CME, incorporating age, leg length, and BMI, offered marginal improvements but could account for outliers.

Conclusions:

• Cadence-based metabolic equations provide a more accurate and practical method for assessing walking intensity, especially during overground ambulation.
• These CME offer a valuable tool for free-living physical activity monitoring and exercise science research.
• The developed CME are a significant advancement over speed-based equations for real-world walking intensity quantification.