TY - JOUR

T1 - Effect of antioxidant supplementation on insulin sensitivity in response to endurance exercise training

AU - Yfanti, Christina

AU - Nielsen, Anders R

AU - Åkerström, Thorbjörn

AU - Nielsen, Søren

AU - Rose, Adam John

AU - Richter, Erik A.

AU - Lykkesfeldt, Jens

AU - Fischer, Christian P

AU - Pedersen, Bente Klarlund

N1 - CURIS 2011 5200 024

PY - 2011

Y1 - 2011

N2 - While production of reactive oxygen and nitrogen species (RONS) is associated with some of the beneficial adaptations to regular physical exercise, it is not established whether RONS play a role in the improved insulin-stimulated glucose uptake in skeletal muscle obtained by endurance training. To assess the effect of antioxidant supplementation during endurance training on insulin-stimulated glucose uptake, twenty-one young healthy (age 29±1 y; BMI 25±3 Kg m(-2)) men were randomly assigned into either an antioxidant (AO; 500 mg vitamin C and 400 IU vitamin E (a-tocopherol) daily) or a placebo (PL) group that both underwent a supervised intense endurance-training program, 5 times per week for 12 weeks. A 3-hour euglycemic-hyperinsulinemic clamp, a maximal oxygen consumption (VO(2max)) and maximal power output (P(max)) test, and body composition measurements (fat mass, fat-free mass) were performed before and after the training. Muscle biopsies were obtained for determination of the concentration and activity of proteins regulating glucose metabolism. Although plasma levels of vitamin C (P <0.05) and a-tocopherol (P <0.05) increased markedly in the AO group, insulin-stimulated glucose uptake increased similarly in both the AO (17.2%, P <0.05) and the PL (18.9%, P <0.05) group in response to training. VO(2max) and P(max) also increased similarly in both groups (time effect: P <0.0001 for both) as well as protein content of GLUT4, hexokinase 2 and total Akt (time effect: P = 0.05 for all). Our results indicate that administration of antioxidants during strenuous endurance training has no effect on the training-induced increase in insulin sensitivity, in healthy individuals.

AB - While production of reactive oxygen and nitrogen species (RONS) is associated with some of the beneficial adaptations to regular physical exercise, it is not established whether RONS play a role in the improved insulin-stimulated glucose uptake in skeletal muscle obtained by endurance training. To assess the effect of antioxidant supplementation during endurance training on insulin-stimulated glucose uptake, twenty-one young healthy (age 29±1 y; BMI 25±3 Kg m(-2)) men were randomly assigned into either an antioxidant (AO; 500 mg vitamin C and 400 IU vitamin E (a-tocopherol) daily) or a placebo (PL) group that both underwent a supervised intense endurance-training program, 5 times per week for 12 weeks. A 3-hour euglycemic-hyperinsulinemic clamp, a maximal oxygen consumption (VO(2max)) and maximal power output (P(max)) test, and body composition measurements (fat mass, fat-free mass) were performed before and after the training. Muscle biopsies were obtained for determination of the concentration and activity of proteins regulating glucose metabolism. Although plasma levels of vitamin C (P <0.05) and a-tocopherol (P <0.05) increased markedly in the AO group, insulin-stimulated glucose uptake increased similarly in both the AO (17.2%, P <0.05) and the PL (18.9%, P <0.05) group in response to training. VO(2max) and P(max) also increased similarly in both groups (time effect: P <0.0001 for both) as well as protein content of GLUT4, hexokinase 2 and total Akt (time effect: P = 0.05 for all). Our results indicate that administration of antioxidants during strenuous endurance training has no effect on the training-induced increase in insulin sensitivity, in healthy individuals.

U2 - 10.1152/ajpendo.00207.2010

DO - 10.1152/ajpendo.00207.2010

M3 - Journal article

C2 - 21325105

VL - 300

SP - E761-E770

JO - American Journal of Physiology - Endocrinology and Metabolism

JF - American Journal of Physiology - Endocrinology and Metabolism

SN - 0193-1849

IS - 5

ER -