1. Effect of a 2-h hyperglycemic-hyperinsulinemic glucose clamp to promote glucose storage on endurance exercise performance.
- Author
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MacLaren, D. P. M., Mohebbi, H., Nirmalan, M. A., Keegan, M. A., Best, C. T., Perera, D., Harvie, M. N., Campbell, I. T., and Nirmalan, M
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ENDURANCE sports , *GLUCOSE , *HYPERGLYCEMIA , *OXYGEN consumption , *PHYSIOLOGICAL transport of carbon dioxide , *CYCLING , *PHYSIOLOGY , *GLUCOSE metabolism , *ATHLETIC ability , *BIOCHEMISTRY , *BIOLOGICAL transport , *BLOOD sugar , *COMPARATIVE studies , *EXERCISE , *HYPERINSULINISM , *INSULIN , *PHENOMENOLOGY , *RESEARCH methodology , *MEDICAL cooperation , *PHYSICAL fitness , *RESEARCH , *TIME , *EVALUATION research , *GLUCOSE clamp technique - Abstract
Carbohydrate stores within muscle are considered essential as a fuel for prolonged endurance exercise, and regimes for enhancing such stores have proved successful in aiding performance. This study explored the effects of a hyperglycaemic-hyperinsulinemic clamp performed 18 h previously on subsequent prolonged endurance performance in cycling. Seven male subjects, accustomed to prolonged endurance cycling, performed 90 min of cycling at ~65% VO(2max) followed by a 16-km time trial 18 h after a 2-h hyperglycemic-hyperinsulinemic clamp (HCC). Hyperglycemia (10 mM) with insulin infused at 300 mU/m(2)/min over a 2-h period resulted in a total glucose uptake of 275 g (assessed by the area under the curve) of which glucose storage accounted for about 73% (i.e. 198 g). Patterns of substrate oxidation during 90-min exercise at 65% VO(2max) were not altered by HCC. Blood glucose and plasma insulin concentrations were higher during exercise after HCC compared with control (p < 0.05) while plasma NEFA was similar. Exercise performance was improved by 49 s and power output was 10-11% higher during the time trial (p < 0.05) after HCC. These data suggest that carbohydrate loading 18 h previously by means of a 2-h HCC improves cycling performance by 3.3% without any change in pattern of substrate oxidation. [ABSTRACT FROM AUTHOR]
- Published
- 2011
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