Ingestão de carboidratos e proteína em cápsulas durante o exercício no calor: efeitos sobre o desempenho físico de atletas no estado alimentado

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

It has been suggested that exercise performance in the heat might be limited by central mechanisms. One of the proposed mechanisms associates increased central serotonergic activity to the onset of fatigue. Different nutritional strategies have been used in an attempt to decrease central serotonergic activity thus improving performance. The purpose of the present study was to verify whether carbohydrates (CHO) or protein (PTN) would improve performance in the heat (31ºC e 50% RH) when subjects were previously fed. Ten well-trained male subjects (26 ± 1 anos; 64.45 ± 2.42 kg; 1,7 ± 0,3 m; 5.38 ± 0.52 % body fat; peak power output 323 ± 13 W; heart rate maxima 190 ± 2 bpm VO2max.70.7 ± 2.8 mLO2.kg-1.min-1) volunteered to took part in the study. The participants performed 60-km self-paced bicycle rides, interspersed with 1-km all-out sprints at the 14th, 29th, 44nd and 60th km, in an environmental chamber. They were subjected randomly to three different treatments, during which they ingested: only water (H2O); water + capsules containing whey-protein isolate (PTNc, 3,9%); water + capsules containing carbohydrates (CHOc, 6%). The last two treatments were run on a double-blinded protocol. Administration of the treatments occurred at the 5th, 15th, 30 th, 45 th and 55 th km. Blood samples were collected through a catheter from a superficial forearm vein at the pre-exercise period and at the 9th, 24th, 39th, 54th and 60th km. The data were analyzed using a Latin Square Design and a General Linear Model, followed by Tukey LSD test when appropriate. No differences in performance times for both 60 km and 1 km sprints were observed between the three treatments. Free fatty acids, tryptophan (TRP), urea, prolactin, rate of perceived exertion, heart rate, core temperature and lactate analyzed over time were also similar during all treatments. Plasma glucose and serum insulin were higher in CHOc. Plasma branched chain amino acids (BCAA) were higher in PTNc. The TRP/BCAA ratio was reduced in PTNc. The ingestion of carbohydrates or protein in capsules did not improve exercise performance in the heat, despite changes in some of the peripheral factors proposed in Central Fatigue Hypothesis.

ASSUNTO(S)

carboidratos teses educação física teses fadiga teses calor teses suplementação alimentar decs aptidão fisica teses exercícios físicos teses

ACESSO AO ARTIGO

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