Predicting Walking METs and Energy Expenditure from Speed or Accelerometry

Purpose a) Compare the predictive potential of speed and CSA(hip) (Computer Science Applications accelerometer positioned on the hip) for level terrain walking METs (1 MET = VO₂ of 3.5 mL·kg^-1·min^-1) and energy expenditure (kcal·min^-1); b) cross-validate previously published CSA(hip)- and speed-based MET and energy expenditure prediction equations; c) measure self-paced walking speed, exercise intensity (METs) and energy expenditure in the middle aged population.

Methods Seventy-two 35- to 45-yr-old volunteers walked around a level, paved quadrangle at what they perceived to be a moderate pace. Oxygen consumption was measured using the criterion Douglas bag technique. Speed, CSA(hip), heart rate, and Borg rating of perceived exertion were also monitored.

Results Speed explained 10% more variance of walking METs than CSA(hip). Speed and mass explained 8% more variance of walking energy expenditure (kcal·min) than CSA(hip) and mass. The best previously published regression equations predict our walking METs and energy expenditures within 95% prediction limits of +/- 0.7 METs and +/- 1.0 kcal·min^-1, respectively. Women paced themselves at a significantly higher mean speed (5.5 km·h^-1) and intensity (4.1 METs) than their male counterparts (5.2 km·h^-1 and 3.8 METs). Both genders expended approximately 0.75 kcal·kg^-1 for every kilometer of level terrain walked.

Conclusion Speed-based MET and energy expenditure predictions during level terrain walking were more accurate than those utilizing CSA(hip).

Link to Abstract: http://www.ncbi.nlm.nih.gov/pubmed/16015141