Citation

Roberts JD, Tarpey MD, Kass LS, Tarpey RJ, Roberts MG. J. Int. Soc. Sports Nutr. 2014; 11(1): 8.

Copyright

(Copyright © 2014, International Society of Sports Nutrition)

DOI

10.1186/1550-2783-11-8

PMID

24589205

Abstract

BACKGROUND: Whilst exogenous carbohydrate oxidation (CHOEXO) is influenced by mono- and disaccharide combinations, debate exists whether such beverages enhance fluid delivery and exercise performance. Therefore, this study aimed to ascertain CHOEXO, fluid delivery and performance times of a commercially available maltodextrin/ fructose beverage in comparison to an isocaloric maltodextrin beverage and placebo. METHODS: Fourteen club level cyclists (age: 31.79 +/- 10.02 years; height: 1.79 +/- 0.06 m; weight: 73.69 +/- 9.24 kg; VO2max: 60.38 +/- 9.36 mL . kg.-1 min-1) performed three trials involving 2.5 hours continuous exercise at 50% maximum power output (Wmax: 176.71 +/- 25.92 W) followed by a 60 km cycling performance test. Throughout each trial, athletes were randomly assigned, in a double-blind manner, either: (1) 1.1 g . min-1 maltodextrin + 0.6 g . min-1 fructose (MD + F), (2) 1.7 g . min-1 of maltodextrin (MD) or (3) flavoured water (P). In addition, the test beverage at 60 minutes contained 5.0 g of deuterium oxide (2H2O) to assess quantification of fluid delivery. Expired air samples were analysed for CHOEXO according to the 13C/12C ratio method using gas chromatography continuous flow isotope ratio mass spectrometry. RESULTS: Peak CHOEXO was significantly greater in the final 30 minutes of submaximal exercise with MD + F and MD compared to P (1.45 +/- 0.09 g . min-1, 1.07 +/- 0.03 g . min-1and 0.00 +/- 0.01 g . min-1 respectively, P < 0.0001), and significantly greater for MD + F compared to MD (P = 0.005). The overall appearance of 2H2O in plasma was significantly greater in both P and MD + F compared to MD (100.27 +/- 3.57 ppm, 92.57 +/- 2.94 ppm and 78.18 +/- 4.07 ppm respectively, P < 0.003). There was no significant difference in fluid delivery between P and MD + F (P = 0.078). Performance times significantly improved with MD + F compared with both MD (by 7 min 22 s +/- 1 min 56 s, or 7.2%) and P (by 6 min 35 s +/- 2 min 33 s, or 6.5%, P < 0.05) over 60 km. CONCLUSIONS: A commercially available maltodextrin-fructose beverage improves CHOEXO and fluid delivery, which may benefit individuals during sustained moderate intensity exercise. The greater CHOEXO observed when consuming a maltodextrin-fructose beverage may support improved performance times.

Language: en