Assessing a commercially available sports drink on exogenous carbohydrate oxidation, fluid delivery and sustained exercise performance

Abstract

BackgroundWhilst 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.MethodsFourteen 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.ResultsPeak 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.ConclusionsA 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.

Multiple Transportable Carbohydrates During Exercise

“…Three additional studies found performance improvements as large as 7-8% for TT completion with glucose-fructose feedings relative to glucose-only feedings (11,50,63). Multiple transportable carbohydrates reduced GI complaints in several studies, including stomach fullness (31,39,50), nausea (40,50,62), abdominal cramps (40,53,62), and the urge to defecate (50). Two studies support the notion that fluid delivery is more rapid with glucose-fructose mixtures (30,50), whereas another suggests that decreases in plasma volume may be minimized (55).…”

“…The largest effect on performance was from the study by Stannard et al (59), in which 1.0 g$min 21 of galactose led to ;15% slower time trial (TT) completion compared with glucose-galactose and glucosefructose mixtures. Three additional studies found performance improvements as large as 7-8% for TT completion with glucose-fructose feedings relative to glucose-only feedings (11,50,63). Multiple transportable carbohydrates reduced GI complaints in several studies, including stomach fullness (31,39,50), nausea (40,50,62), abdominal cramps (40,53,62), and the urge to defecate (50).…”

“…Consequently, increased absorption of carbohydrate molecules with MTC ingestion would be advantageous in terms of fluid delivery to the circulation. In support of this hypothesis, several studies have shown that markers of fluid delivery are improved with glucose-fructose co-ingestion compared with an equivalent concentration of glucose (30,50). Jeukendrup and Moseley (30) used several methods to compare fluid dynamics with the ingestion of a glucose-only solution or a 2:1 glucose-fructose solution (1.5 g$min 21 ).…”

The effect of dilution on the erosive potential of maltodextrin-containing sports drinks

“…Based on these factors, sports drinks have specially-formulated solutions designed to hydrate the body and enhance performance by providing energy supplementation 2,3 .…”

“…It should be considered that these drinks have usually a low pH and variable titratable acidity and both of which are relevant to their potential to cause dental erosion [3][4][5] .…”