Effect of carbohydrate availability on time to exhaustion in exercise performed at two different intensities
Braz. j. med. biol. res
; 42(5): 404-412, May 2009. ilus, tab
Artigo
em Inglês
| LILACS
| ID: lil-511332
Biblioteca responsável:
BR1.1
ABSTRACT
This study examined the effects of pre-exercise carbohydrate availability on the time to exhaustion for moderate and heavy exercise. Seven men participated in a randomized order in two diet and exercise regimens each lasting 3 days with a 1-week interval for washout. The tests were performed at 50 percent of the difference between the first (LT1) and second (LT2) lactate breakpoint for moderate exercise (below LT2) and at 25 percent of the difference between the maximal load and LT2 for heavy exercise (above LT2) until exhaustion. Forty-eight hours before each experimental session, subjects performed a 90-min cycling exercise followed by 5-min rest periods and a subsequent 1-min cycling bout at 125 percent VO2max/1-min rest periods until exhaustion to deplete muscle glycogen. A diet providing 10 percent (CHOlow) or 65 percent (CHOmod) energy as carbohydrates was consumed for 2 days until the day of the experimental test. In the exercise below LT2, time to exhaustion did not differ between the CHOmod and the CHOlow diets (57.22 ± 24.24 vs 57.16 ± 25.24 min). In the exercise above LT2, time to exhaustion decreased significantly from 23.16 ± 8.76 min on the CHOmod diet to 18.30 ± 5.86 min on the CHOlow diet (P < 0.05). The rate of carbohydrate oxidation, respiratory exchange ratio and blood lactate concentration were reduced for CHOlow only during exercise above LT2. These results suggest that muscle glycogen depletion followed by a period of a low carbohydrate diet impairs high-intensity exercise performance.
Texto completo:
Disponível
Coleções:
Bases de dados internacionais
Base de dados:
LILACS
Assunto principal:
Resistência Física
/
Carboidratos da Dieta
/
Metabolismo Energético
/
Metabolismo dos Carboidratos
/
Esforço Físico
Tipo de estudo:
Ensaio clínico controlado
Limite:
Adulto
/
Humanos
/
Masculino
Idioma:
Inglês
Revista:
Braz. j. med. biol. res
Assunto da revista:
Biologia
/
Medicina
Ano de publicação:
2009
Tipo de documento:
Artigo
País de afiliação:
Brasil
Instituição/País de afiliação:
Universidade Estadual de Londrina/BR
/
Universidade Federal de Alagoas/BR
/
Universidade Federal de Lavras/BR
/
Universidade do Estado de Santa Catarina/BR