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Enhanced protein breakdown after eccentric exercise in young and older men.

Publication ,  Journal Article
Fielding, RA; Meredith, CN; O'Reilly, KP; Frontera, WR; Cannon, JG; Evans, WJ
Published in: J Appl Physiol (1985)
August 1991

The effects of eccentric exercise on whole body protein metabolism were compared in five young untrained [age 24 +/- 1 yr, maximal O2 uptake (VO2max) = 49 +/- 6 ml.kg-1.min-1] and five older untrained men (age 61 +/- 1 yr, VO2max = 34 +/- 2 ml.kg-1.min-1). They performed 45 min of eccentric exercise on a cycle ergometer at a power output equivalent to 80% VO2max (182 +/- 18 W). Beginning 5 days before exercise and continuing for at least 10 days after exercise, they consumed a eucaloric diet providing 1.5 g.kg-1.day-1 of protein. Leucine metabolism in the fed state was measured before, immediately after, and 10 days after exercise, with intravenous L-[1-13C]leucine as a tracer (0.115 mumol.kg-1.min-1). Leucine flux increased 9% immediately after exercise (P less than 0.011) and remained elevated 10 days later, with no effect of age. Leucine oxidation increased 19% immediately after exercise and remained 15% above baseline 10 days after exercise (P less than 0.0001), with no effect of age. In the young men, urinary excretion of 3-methylhistidine per gram of creatinine did not increase until 10 days postexercise (P less than 0.05), but in the older men, it increased 5 days after exercise and remained high through 10 days postexercise (P less than 0.05), averaging 37% higher than in the young men. These data suggest that eccentric exercise produces a similar increase in whole body protein breakdown in older and young men, but myofibrillar proteolysis may contribute more to whole body protein breakdown in the older group.

Duke Scholars

Published In

J Appl Physiol (1985)

DOI

ISSN

8750-7587

Publication Date

August 1991

Volume

71

Issue

2

Start / End Page

674 / 679

Location

United States

Related Subject Headings

  • Proteins
  • Physiology
  • Oxygen Consumption
  • Nitrogen
  • Middle Aged
  • Methylhistidines
  • Male
  • Leucine
  • Kinetics
  • Humans
 

Citation

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ICMJE
MLA
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Fielding, R. A., Meredith, C. N., O’Reilly, K. P., Frontera, W. R., Cannon, J. G., & Evans, W. J. (1991). Enhanced protein breakdown after eccentric exercise in young and older men. J Appl Physiol (1985), 71(2), 674–679. https://doi.org/10.1152/jappl.1991.71.2.674
Fielding, R. A., C. N. Meredith, K. P. O’Reilly, W. R. Frontera, J. G. Cannon, and W. J. Evans. “Enhanced protein breakdown after eccentric exercise in young and older men.J Appl Physiol (1985) 71, no. 2 (August 1991): 674–79. https://doi.org/10.1152/jappl.1991.71.2.674.
Fielding RA, Meredith CN, O’Reilly KP, Frontera WR, Cannon JG, Evans WJ. Enhanced protein breakdown after eccentric exercise in young and older men. J Appl Physiol (1985). 1991 Aug;71(2):674–9.
Fielding, R. A., et al. “Enhanced protein breakdown after eccentric exercise in young and older men.J Appl Physiol (1985), vol. 71, no. 2, Aug. 1991, pp. 674–79. Pubmed, doi:10.1152/jappl.1991.71.2.674.
Fielding RA, Meredith CN, O’Reilly KP, Frontera WR, Cannon JG, Evans WJ. Enhanced protein breakdown after eccentric exercise in young and older men. J Appl Physiol (1985). 1991 Aug;71(2):674–679.

Published In

J Appl Physiol (1985)

DOI

ISSN

8750-7587

Publication Date

August 1991

Volume

71

Issue

2

Start / End Page

674 / 679

Location

United States

Related Subject Headings

  • Proteins
  • Physiology
  • Oxygen Consumption
  • Nitrogen
  • Middle Aged
  • Methylhistidines
  • Male
  • Leucine
  • Kinetics
  • Humans