Predicting walking METs and energy expenditure from speed or accelerometry.

Area of Science:

• Exercise Physiology
• Biomechanical Engineering
• Wearable Technology

Background:

• Accurate estimation of energy expenditure (METs) and exercise intensity is crucial for health and fitness monitoring.
• Wearable sensors like accelerometers offer potential for objective physical activity assessment.
• Previous research has explored various methods for predicting walking energy expenditure.

Purpose of the Study:

• To compare the predictive accuracy of walking speed versus hip-worn accelerometer data (CSAhip) for estimating METs and energy expenditure during level walking.
• To cross-validate existing prediction equations for METs and energy expenditure.
• To measure self-paced walking speed, intensity, and energy expenditure in middle-aged adults.

Main Methods:

• Seventy-two adults aged 35-45 years performed self-paced walking on a level surface.
• Oxygen consumption was measured using the Douglas bag technique.
• Walking speed, hip-worn accelerometer data (CSAhip), heart rate, and perceived exertion were recorded.

Main Results:

• Walking speed explained 10% more variance in walking METs compared to CSAhip.
• Speed and body mass explained 8% more variance in energy expenditure than CSAhip and mass.
• Previously published equations predicted METs within +/- 0.7 METs and energy expenditure within +/- 1.0 kcal/min.
• Women walked faster (5.5 km/h) and at higher intensity (4.1 METs) than men (5.2 km/h, 3.8 METs).

Conclusions:

• Walking speed is a more accurate predictor of METs and energy expenditure during level terrain walking than hip-worn accelerometer data (CSAhip).
• Existing prediction equations demonstrate reasonable accuracy for estimating walking intensity and energy expenditure.
• Gender differences exist in self-paced walking speed and intensity in middle-aged adults.