A new device to estimate VO2 during incline walking by accelerometry and barometry

Area of Science:

• Exercise Physiology
• Biomedical Engineering
• Wearable Technology

Background:

• Accelerometry is commonly used to estimate oxygen consumption (VO2) during physical activity.
• However, accelerometry alone can be biased during incline walking.
• Altitude changes, measured by barometry, may improve VO2 estimation.

Purpose of the Study:

• To investigate if adding barometric altitude change data improves VO2 estimation by accelerometry during incline walking.
• To develop and validate a regression equation for VO2 estimation using accelerometry and barometry.

Main Methods:

• 42 healthy adults (mean age 63 yrs) underwent graded treadmill walking with varying inclines (-15% to +15%) and speeds.
• Oxygen consumption (VO2) was measured via respiratory gas analysis.
• A portable device with a triaxial accelerometer and barometer measured accelerations and altitude changes.
• A regression equation was derived to estimate VO2 from vector magnitude (VM), vertical upward speed (Hu), and vertical downward speed (Hd).

Main Results:

• A regression equation (VO2 = 0.044 VM + 1.365 Hu + 0.553 Hd) showed high correlation (r=0.93) with measured VO2.
• Estimated VO2 closely matched measured VO2 (y=0.97x, r=0.88) with minimal bias (-0.20 +/- 3.47 mL x kg(-1) x min(-1)).
• Validation on an outdoor hill confirmed the equation's precision.

Conclusions:

• A device combining accelerometry and barometry can precisely estimate oxygen consumption (VO2) during walking on various inclines.
• This integrated approach offers a more accurate method for assessing energy expenditure during dynamic activities.