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Original articles  BIOCHEMISTRY 

The Journal of Sports Medicine and Physical Fitness 2003 June;43(2):236-42

Copyright © 2009 EDIZIONI MINERVA MEDICA

lingua: Inglese

Variation in plasma amino acid concentrations during a cycling competition

Medelli J. 1, Lounana J. 1, Hill D. 2

1 Biology and Sports Medicine Unit, CHU-Hôpital-Nord, Amiens, France 2 Department of Kinesiology, Health Promotion, and Recreation University of North Texas, Denton, Texas USA


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Aim. The vari­a­tions in ­plasma con­cen­tra­tions of 24 amino acids (AAs) ­were meas­ured, ­taking ­into ­account mod­ifi­ca­tions in ­plasma ­volume, in 7 ­male sub­jects, pro­fes­sional ­cyclists, ­during the ­first 2 ­stages (EI and EII) of the com­pe­ti­tion “4 ­Days of Dun­kirk 1999”.
­Methods. ­Blood sam­ples ­were ­taken ­before the ­start and at the end of ­each ­stage. At the end of EI a sig­nif­i­cant reduc­tion (p<0.02) in α-ami­no­bu­tyric ­acid was ­observed (-38%) and a sig­nif­i­cant ­increase (Wil­coxon 0.01­Results. The ­recovery ­period was char­ac­ter­ised by ­increases in pre­vi­ously ­reduced AAs and ­vice ­versa.
Con­clu­sion. ­These ­results ­show ­that cel­lular use of ­plasma AAs in the endu­rance ­cyclist ­could ­differ ­between the ­first ­hours of com­pe­ti­tion and the sub­se­quent ­stages, pos­sibly in rela­tion to the ­gradual ­increase in ­stress ­level as the ­stages ­progress; ­they ­also sug­gest ­that appro­priate con­sid­er­a­tion ­should be ­given to the ­quality of pro­tein ­inputs in the nutri­tion of ­cyclists ­involved in a ­high-­level ­stage com­pe­ti­tion.

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