Document Detail


Can energetic expenditure be minimized by performing activity intermittently?
MedLine Citation:
PMID:  11171310     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Previous research has shown that the energetic expense per unit distance traveled for one bout of short-duration activity is much greater than the energetic expense associated with long-duration activity. However, animals are often seen moving intermittently, with these behaviors characterized by brief bouts of activity interspersed with brief pauses. We hypothesized that, when multiple bouts of brief activity are performed intermittently, the energetic cost per unit distance is less than when only one short bout is performed. Mice were run 1, 2, 3, 5, 9 or 13 times for 15 s at their maximal speed within a 375 s period while enclosed in an open-flow respirometry system on a treadmill. The mice were also run continuously for 375 s. Following the last sprint and the continuous run, the mice remained in the respirometry chamber until their vO2 reached resting levels. Excess exercise oxygen consumption (EEOC), the excess volume of oxygen consumed during the exercise period, increased from 0.03+/-0.01 to 0.40+/-0.02 ml O2g(-)(1) (mean +/- s.e.m., N=9) with activity frequency. However, the excess post-exercise oxygen consumption (EPOC), or volume of oxygen consumed during the recovery period, was independent of activity frequency (range 0.91-1.16 ml O2g(-)(1)) and accounted for more than 80 % of the total metabolic cost when activity was performed intermittently. Lactate concentration was measured at rest, immediately after running and immediately after recovering from running 1, 5 and 13 times within the 375 s period. After running, [lactate] was significantly higher than resting values, but following recovery, [lactate] had reached resting values. The net cost of activity, C(act), calculated by summing EEOC and EPOC and then dividing by the distance run, decreased significantly from 132+/-38 to 6+/-1 ml O2g(-)(1 )km(-)(1) as activity frequency increased. When these values for C(act) were compared with the cost of running continuously for the same amount of time, the values were identical. Therefore, we conclude that animals can minimize energetic expenditure by performing brief behaviors more frequently, just as they can minimize these costs if they increase the duration of continuous behaviors.
Authors:
E B Edwards; T T Gleeson
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  204     ISSN:  0022-0949     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2001 Feb 
Date Detail:
Created Date:  2001-02-22     Completed Date:  2001-06-28     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  599-605     Citation Subset:  IM    
Affiliation:
Department of Environmental, Population and Organismic Biology, University of Colorado, Boulder, CO 80309-0334, USA. bakerej@ucsu.colorado.edu
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MeSH Terms
Descriptor/Qualifier:
Animals
Energy Metabolism / physiology
Locomotion / physiology*
Mice
Physical Conditioning, Animal

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