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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #312468
Title: Predicting metabolic rate across walking speed: One fit for all body sizes?

Author
item WEYAND, PETER - Southern Methodist University
item SMITH, BETHANY - Children'S Nutrition Research Center (CNRC)
item SCHULTZ, NICOLE - Southern Methodist University
item LUDLOW, LINDSAY - Southern Methodist University
item PUYAU, MAURICE - Children'S Nutrition Research Center (CNRC)
item BUTTE, NANCY - Children'S Nutrition Research Center (CNRC)

Submitted to: Journal of Applied Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/2013
Publication Date: 8/8/2013
Citation: Weyand, P.G., Smith, B.R., Schultz, N.S., Ludlow, L.W., Puyau, M.R., Butte, N.F. 2013. Predicting metabolic rate across walking speed: One fit for all body sizes? Journal of Applied Physiology. 115:1332-1342.

Interpretive Summary: We developed a "one-size-fits-all" model that can tell us the energy (or calories) a human would need while walking based on the person's height, weight, and walking speed. Our three-part model proposes that the energy spent per kilogram per step at equivalent walking speeds is the same irrespective of the person's height. We measured the amount of oxygen or energy used by 78 people across a range of body weights and heights while walking on a treadmill at varying speeds. We tested the body size independence of our model by looking at best-fit formulas in 4 different groups based on height: short, moderately short, moderately tall, and tall. The average walking energy expenditure predicted in these four groups agreed closely with each other at four different speeds. We found that our model was able to accurately predict the walking energy expenditure of the validation group. We now know that the energy used in human walking can be predicted accurately based on the person's height, weight, and walking speed.

Technical Abstract: We formulated a "one-size-fits-all" model that predicts the energy requirements of level human walking from height, weight, and walking speed. Our three-component model theorizes that the energy expended per kilogram per stride is independent of stature at mechanically equivalent walking speeds. We measured steady-state rates of oxygen uptake of 78 subjects who spanned a nearly two fold range of statures (1.07-2.11 m) and seven fold range of body masses (16-112 kg) at treadmill speeds from 0.4 to 1.9 m/s. We tested the size independence of the model by deriving best-fit equations in the form of the model on four stature groups (n = 15): short, moderately short, moderately tall, and tall. The mean walking metabolic rates predicted by these four independently derived equations for the same set of reference subjects (n = 16; stature range: 1.30-1.90 m) agreed with one another to within an average of 5.2 +/- 3.7% at the four intermediate speeds in our protocol. We next evaluated the model's gross predictive accuracy by dividing our 78 subjects into 39 stature-matched pairs of experimental and validation group subjects. The model best-fit equation derived on the experimental group subjects predicted the walking metabolic rates of the validation group subjects to within an average of 8.1 +/- 6.7% (R(2) = 0.90; standard error of estimate = 1.34 ml O2/kg(-1)/min(-1)). The predictive error of the American College of Sports Medicine equation (18.0 +/- 13.1%), which does not include stature as a predictor, was more than twice as large for the same subject group. We conclude that the energy cost of level human walking can be accurately predicted from height, weight, and walking speed.