Effect of endurance training on hepatic glycogenolysis and gluconeogenesis during prolonged exercise in men.
Am J Physiol
; 268(3 Pt 1): E375-83, 1995 Mar.
Article
em En
| MEDLINE
| ID: mdl-7900783
ABSTRACT
In humans, endurance training markedly reduces the rate of hepatic glucose production during exercise. To determine whether this is due to a reduction in glycogenolysis, in gluconeogenesis, or in both processes, six men were studied at rest and during 2 h of cycle ergometer exercise at 60% pretraining peak O2 consumption (VO2peak), both before and after completion of a strenuous endurance training program (cycling at 75-100% VO2peak for 45-90 min/day, 6 days/wk for 12 wk). The overall rate of glucose appearance (Ra) was determined using a primed continuous infusion of [6,6-2H]glucose, whereas the rate of gluconeogenesis (Rgng) was estimated from the incorporation of 13C into glucose (via pyruvate carboxylase) from simultaneously infused [13C]bicarbonate. Training did not affect glucose kinetics at rest but reduced the average Ra during exercise by 42% [from 36.8 +/- 3.8 to 21.5 +/- 3.6 (SE) mumol.min-1.kg-1; P < 0.001]. This decrease appeared to be mostly due to a reduction in hepatic glycogenolysis. However, the estimated Rgng during exercise also decreased significantly (P < 0.001) with training, falling from 7.5 +/- 1.6 mumol.min-1.kg-1 (23 +/- 3% of total Ra) before training to 3.1 +/- 0.6 mumol.min-1.kg-1 (14 +/- 3% of total Ra) after training. These training-induced adaptations in hepatic glucose metabolism were associated with an attenuated hormonal response to exercise (i.e., higher insulin and lower glucagon, norepinephrine, and epinephrine concentrations) as well as a reduced availability of gluconeogenic precursors (i.e., lower lactate and glycerol concentrations). We conclude that endurance training reduces both hepatic glycogenolysis and gluconeogenesis during prolonged exercise in men.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Resistência Física
/
Gluconeogênese
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Glicogênio
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Fígado
Limite:
Adult
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Humans
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Male
Idioma:
En
Revista:
Am J Physiol
Ano de publicação:
1995
Tipo de documento:
Article
País de publicação:
EEUU
/
ESTADOS UNIDOS
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ESTADOS UNIDOS DA AMERICA
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EUA
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UNITED STATES
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UNITED STATES OF AMERICA
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US
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USA