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The Journal of Sports Medicine and Physical Fitness 2000 September;40(3):240-6


language: English

Effects of branched-chain amino acid supplementation on serum creatine kinase and lactate dehydrogenase after prolonged exercise

Coombes J. S., McNaughton L. R.

Centre for Human Movement, University of Tasmania, Launceston, Australia


Background. The aim of ­this ­study was to exam­ine the ­effects of ­branched-­chain ami­no ­acid (­BCAA) sup­ple­men­ta­tion on ser­um indi­ca­tors of mus­cle dam­age ­after pro­longed exer­cise. We hypoth­e­sized ­that ­BCAA sup­ple­men­ta­tion ­would ­reduce the ser­um activ­ities of intra­mus­cu­lar ­enzymes asso­ciat­ed ­with mus­cle dam­age.
Methods. To ­test ­this hypoth­e­sis, six­teen ­male sub­jects ­were ­assigned to one of two ­groups: the sup­ple­men­tal ­group (con­sum­ing 12 g·d-1 ­BCAA for 14 d in addi­tion to ­their nor­mal ­diet) or the con­trol ­group (nor­mal ­diet ­only). Baseline ser­um crea­tine ­kinase (CK) and lac­tate dehy­drog­e­nase (LDH), ­shown to be accu­rate indi­ca­tors of mus­cle dam­age, ­were deter­mined dur­ing the ­week ­before the exer­cise ­test. The exer­cise ­test was admin­is­tered on day sev­en and ­required the sub­jects to ­cycle for 120 min on an ergom­e­ter at approx­i­mate­ly 70% .VO2max. Blood sam­ples ­were tak­en ­prior to and imme­di­ate­ly fol­low­ing exer­cise and at 1 hr, 2 hrs, 3 hrs, 4 hrs, 1 d, 3 d, 5 d and 7 d ­postexer­cise. All sub­jects ­were ­required ­have ­their ­diets ana­lyzed dai­ly dur­ing the 14 d.
Results. Dietary anal­y­ses indi­cat­ed ­that all sub­jects con­sumed the rec­om­mend­ed dai­ly ­intake of ­BCAA (0.64 g.kg-1) in ­their nor­mal ­diets. Baseline ser­um val­ues for CK and LDH ­were not dif­fer­ent ­between ­groups in the 7 d ­prior to the ­test (p>0.05). However ­there ­were sig­nif­i­cant increas­es (p<0.05) ­between the pre-exer­cise and ­postexer­cise val­ues for LDH and CK ­until 5 d ­postexer­cise ­test. Importantly, the ­BCAA sup­ple­men­ta­tion sig­nif­i­cant­ly ­reduced ­this ­change in LDH ­from 2hrs to 5 d post­test, and CK ­from 4 hrs to 5 d post-­test (p<0.05).
Conclusions. These ­results indi­cate ­that sup­ple­men­tary ­BCAA ­decreased ser­um con­cen­tra­tions of the intra­mus­cu­lar ­enzymes CK and LDH fol­low­ing pro­longed exer­cise, ­even ­when the rec­om­mend­ed ­intake of ­BCAA was ­being con­sumed. This obser­va­tion sug­gests ­that ­BCAA sup­ple­men­ta­tion may ­reduce the mus­cle dam­age asso­ciat­ed ­with endu­rance exer­cise.

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