Home > Riviste > The Journal of Sports Medicine and Physical Fitness > Fascicoli precedenti > The Journal of Sports Medicine and Physical Fitness 2002 September;42(3) > The Journal of Sports Medicine and Physical Fitness 2002 September;42(3):320-9

ULTIMO FASCICOLO
 

JOURNAL TOOLS

eTOC
Per abbonarsi PROMO
Sottometti un articolo
Segnala alla tua biblioteca
 

ARTICLE TOOLS

Estratti
Permessi

 

Original articles  BODY COMPOSITION, SPORT NUTRITION AND SUPPLEMENTATION 

The Journal of Sports Medicine and Physical Fitness 2002 September;42(3):320-9

Copyright © 2009 EDIZIONI MINERVA MEDICA

lingua: Inglese

Pre-exercise oral creatine ingestion does not improve prolonged intermittent sprint exercise in humans

Preen D., Dawson B., Goodman C., Lawrence S. *, Beilby J. **, Ching S. **

From the Department of Human Movement and Exercise Science, The University of Western Australia, Crawley, Australia *Western Australian Institute of Sport, Challenge Stadium Mt Claremont, Australia **The Western Australian Centre for Pathology and Medical Research, QEII Medical Centre, Nedlands, Australia


PDF


Back­ground. ­This inves­ti­ga­tion deter­mined ­whether pre-exer­cise ­oral Cr inges­tion ­could ­enhance pro­longed inter­mit­tent ­sprint exer­cise per­for­mance.
­Methods. Experi­mental ­design: a ran­dom­ised, ­double-­blind cross­over ­design was ­employed. Set­ting: ­testing was per­formed at the ­Western Aus­tra­lian Insti­tute of ­Sport and par­tic­i­pants ­were mon­i­tored and ­treated by ­both sci­en­tific and med­ical per­sonnel. Par­tic­i­pants: ­eight ­active, but not ­well-­trained ­males ­with a back­ground in mul­tiple-­sprint ­based ­sports ­acted as sub­jects for ­this inves­ti­ga­tion. Inter­ven­tions: sub­jects ­ingested ­either 15 g Cr.H2O or pla­cebo 120 min and 60 min ­prior to the ­start of an 80-min max­imal ­sprint ­cycling ­task (10 ­sets of mul­tiple 6-sec ­sprints ­with var­ying ­active recov­eries). Sub­jects ­were ­retested 14 ­days ­later, ­being ­required to ­ingest the alter­nate sup­ple­ment and ­repeat the exer­cise ­test. Meas­ures: per­for­mance var­i­ables (­work ­done and ­peak ­power) ­were ­obtained ­throughout the exer­cise chal­lenge. ­Muscle biop­sies (­vastus lat­er­alis) ­were ­taken preexer­cise as ­well as imme­di­ately and 3 min ­post-exer­cise in ­order to deter­mine con­cen­tra­tions of ATP, PCr, Cr, La- and gly­cogen. ­Venous ­blood was ­drawn ­prior to and on ­four occa­sions ­during the exer­cise ­test, and ana­lysed for Cr, NH3+, La- and pH.
­Results. ­Serum Cr con­cen­tra­tions ­were ­raised to a ­peak of 2348±223 ­µmol·l-1 ­prior to the com­mence­ment of exer­cise ­after Cr inges­tion. ­There ­were no sig­nif­i­cant ­changes in any ­cycling per­for­mance param­e­ters fol­lowing Cr inges­tion, ­although ­blood La- was sig­nif­i­cantly ­lower (p<0.05) ­than pla­cebo at all ­time ­points ­during exer­cise, and ­plasma NH3+ accu­mu­la­tion was ­also sig­nif­i­cantly ­reduced (p<0.05) in the Cr con­di­tion, but ­only in the ­second ­half of the 80-min exer­cise ­test. ­Muscle ATP and TCr ­levels as ­well as post­ex­er­cise PCr replen­ish­ment ­were unaf­fected fol­lowing Cr admin­is­tra­tion.
Con­clu­sions. The ­data sug­gest ­that ­although the pre-exer­cise inges­tion of a ­large Cr ­dose was ­shown to ­have ­some ­impact on ­blood ­borne metab­olites, it ­does not ­improve max­imal pro­longed inter­mit­tent ­sprint exer­cise per­for­mance, pos­sibly due to an insuf­fi­cient ­time ­allowed for ­uptake of ­serum Cr by skel­etal ­muscle to ­occur. There­fore, ­this ­form of ­loading ­does not pro­vide an alter­na­tive ­method of Cr sup­ple­men­ta­tion to the tra­di­tional ­five-day sup­ple­men­ta­tion ­regimes estab­lished by pre­vious ­research.

inizio pagina