Accession Number : ADA618979
Title : Estimating Instantaneous Energetic Cost During Gait Adaptation
Descriptive Note : Research rept.
Corporate Author : SIMON FRASER UNIV BURNABY (BRITISH COLUMBIA)
Personal Author(s) : Selinger, Jessica C ; Donelan, J M
Report Date : 31 Aug 2014
Pagination or Media Count : 31
Abstract : Respiratory measures of oxygen and carbon dioxide are routinely used to estimate the body s steady-state metabolic energy use. However, slow mitochondrial dynamics, long transit times, complex respiratory control mechanisms, and high breath-by-breath variability obscure the relationship between the body's instantaneous energy demands (instantaneous energetic cost) and that measured from respiratory gases (measured energetic cost). The purpose of this study was to expand on traditional methods of assessing metabolic cost by estimating instantaneous energetic cost during gait adaptation and other non-steady state conditions. To accomplish this goal, we first imposed known changes in energy use (input), while measuring the breath-by-breath response (output). We used these input/output relationships to model the body as a dynamic system that maps instantaneous to measured energetic cost. We found that a first-order linear differential equation well approximates transient energetic cost responses during gait. Across all subjects, model fits were parameterized by an average time constant (tau) of 42 +/- 12 s with an average R(2) of 0.94 +/- 0.05 (mean +/- SD). Armed with this input/output model, we next tested whether we could use it to reliably estimate instantaneous energetic cost from breath-by-breath measures under conditions that simulated dynamically changing gait. A comparison of the imposed energetic cost profiles and our estimated instantaneous cost demonstrated a close correspondence, supporting the use our methodology to study the role of energetics during locomotor adaptation and learning.
Descriptors : *ADAPTATION(PHYSIOLOGY) , *BIOINSTRUMENTATION , *ENERGY CONSUMPTION , *EXPERIMENTAL DESIGN , BIOCHEMICAL OXYGEN DEMAND , EXERCISE(PHYSIOLOGY) , METABOLISM , RESPIRATION , WALKING
Subject Categories : Biochemistry
Anatomy and Physiology
Medicine and Medical Research
Biomedical Instrumentation and Bioengineering
Distribution Statement : APPROVED FOR PUBLIC RELEASE