Predicting walking METs and energy expenditure from speed or accelerometry

Purpose: a) Compare the predictive potential of speed and CSAP (Computer Science Applications accelerometer positioned on the hip) for level terrain walking METs (1 MET = (V) over dot O-2 of 3.5 mL center dot kg(-1)center dot min(-1)) and energy expenditure (kcal center dot 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 center dot min(-1)) 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 (8) and +/- 1.0 kcal center dot min(-1) (23), respectively. Women paced themselves at a significantly higher mean speed (5.5 km center dot h(-1)) and intensity (4.1 METs) than their male counterparts (5.2 km center dot h(-1) and 3.8 METs). Both genders expended similar to 0.75 kcal center dot 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).