Document Detail

Contributions of working muscle to whole body lipid metabolism are altered by exercise intensity and training.
MedLine Citation:
PMID:  16896167     Owner:  NLM     Status:  MEDLINE    
To evaluate the contribution of working muscle to whole body lipid oxidation, we examined the effects of exercise intensity and endurance training (9 wk, 5 days/wk, 1 h, 75% Vo(2 peak)) on whole body and leg free fatty acid (FFA) kinetics in eight male subjects (26 +/- 1 yr, means +/- SE). Two pretraining trials [45 and 65% Vo(2 max) (45UT, 65UT)] and two posttraining trials [65% of pretraining Vo(2 peak) (ABT), and 65% of posttraining Vo(2 peak) (RLT)] were performed using [1-(13)C]palmitate infusion and femoral arteriovenous sampling. Training increased Vo(2 peak) by 15% (45.2 +/- 1.2 to 52.0 +/- 1.8, P < 0.05). Muscle FFA fractional extraction was lower during exercise (EX) compared with rest regardless of workload or training status ( approximately 20 vs. 48%, P < 0.05). Two-leg net FFA balance increased from net release at rest ( approximately -36 micromol/min) to net uptake during EX for 45UT (179 +/- 75), ABT (236 +/- 63), and RLT (136 +/- 110) (P < 0.05), but not 65UT (51 +/- 127). Leg FFA tracer measured uptake was higher during EX than rest for all trials and greater during posttraining in RLT (716 +/- 173 micromol/min) compared with pretraining (45UT 450 +/- 80, 65UT 461 +/- 72, P < 0.05). Leg muscle lipid oxidation increased with training in ABT (730 +/- 163 micromol/min) vs. 65UT (187 +/- 94, P < 0.05). Leg muscle lipid oxidation represented approximately 62 and 30% of whole body lipid oxidation at lower and higher relative intensities, respectively. In summary, training can increase working muscle tracer measured FFA uptake and lipid oxidation for a given power output, but both before and after training the association between whole body and leg lipid metabolism is reduced as exercise intensity increases.
Anne L Friedlander; Kevin A Jacobs; Jill A Fattor; Michael A Horning; Todd A Hagobian; Timothy A Bauer; Eugene E Wolfel; George A Brooks
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Publication Detail:
Type:  Journal Article; Randomized Controlled Trial; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2006-08-08
Journal Detail:
Title:  American journal of physiology. Endocrinology and metabolism     Volume:  292     ISSN:  0193-1849     ISO Abbreviation:  Am. J. Physiol. Endocrinol. Metab.     Publication Date:  2007 Jan 
Date Detail:
Created Date:  2007-01-04     Completed Date:  2007-02-16     Revised Date:  2007-12-03    
Medline Journal Info:
Nlm Unique ID:  100901226     Medline TA:  Am J Physiol Endocrinol Metab     Country:  United States    
Other Details:
Languages:  eng     Pagination:  E107-16     Citation Subset:  IM    
Dept. of Integrative Biology, 3060 Valley Life Science Bldg., Univ. of California Berkeley, Berkeley, CA 94720-3140, USA.
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MeSH Terms
Energy Metabolism
Exercise / physiology*
Fatty Acids, Nonesterified / analysis
Leg / blood supply
Lipid Metabolism / physiology*
Lipid Peroxidation
Muscle, Skeletal / metabolism,  physiology*
Physical Endurance / physiology*
Regional Blood Flow
Whole-Body Counting
Grant Support
Reg. No./Substance:
0/Fatty Acids, Nonesterified

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