Relationship between leucine oxidation and oxygen consumption during steady-state exercise.
OBJECTIVE
The purpose of this study was to assess the relationship between whole-body leucine oxidation and oxygen consumption during steady-state exercise. Our hypothesis was that leucine oxidation will be responsive to increased whole-body energy needs.


METHODS
Sixteen healthy individuals (7 women and 9 men) were infused with a stable isotope of leucine and, for comparison purposes, lysine during 60 min of moderate-intensity exercise.


RESULTS
Leucine oxidation was increased (P < 0.05) and nonoxidative leucine disposal was decreased (P < 0.05), whereas leucine and lysine rate of appearance remained unchanged (P = NS) during exercise. Linear regression analysis indicated a modest relationship between leucine oxidation and steady-state oxygen consumption (R = 0.69; P < 0.003) during steady-state exercise. The coefficient of determination (R(2) = 0.49) indicates that approximately half of the variance in whole-body leucine oxidation during exercise can be explained by whole-body oxygen consumption.


CONCLUSIONS
In a statistically appropriate sample size of humans whose dietary intake was controlled, the whole-body rate of leucine oxidation during exercise was only partially influenced by energy demands.
Lamont
L S
LS
Exercise Science Program, the University of Rhode Island, Kingston, RI 02881, USA. lla4983u@postoffice.uri.edu
McCullough
A J
AJ
Kalhan
S C
SC
D000328:Adult; D004032:Diet; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007930:Leucine / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D010101:Oxygen Consumption
D007930:Leucine