title: The ingestion of protein with a maltodextrin and fructose beverage on substrate utilisation and exercise performance.
abstract: The study investigated the ingestion of maltodextrin, fructose, and protein on exogenous carbohydrate oxidation (CHOEXO) and exercise performance. Seven trained cyclists and (or) triathletes (maximal oxygen consumption, 59.20 ± 9.00 mL · kg(-1) · min(-1)) performed 3 exercise trials that consisted of 150 min of cycling at 50% maximal power output (160 ± 11 W), followed by a 60-km time trial. One of 3 beverages were randomly assigned during each trial and consumed at 15-min intervals: (i) 0.84 g · min(-1) maltodextrin + 0.52 g · min(-1) fructose + 0.34 g · min(-1) protein (MD+F+P); (ii) 1.10 g · min(-1) maltodextrin + 0.60 g · min(-1) fructose (MD+F); or (iii) 1.70 g · min(-1) maltodextrin (MD). CHO(EXO) and fuel utilisation were assessed via measurement of expired air (13)C content and indirect calorimetry, respectively. Mean total CHO oxidation (CHOTOT) rates were 2.35 ± 0.18, 2.76 ± 0.08, and 2.61 ± 0.17 g · min(-1) with MD, MD+F, and MD+F+P, respectively, although not significantly different. Peak CHO(EXO) rates with MD+F were significantly greater by 41.4% (p = 0.001) and 45.4% (p = 0.0001) compared with MD+F+P and MD, respectively (1.57 ± 0.22 g · min(-1), 1.11 ± 0.08 g · min(-1), and 1.08 ± 0.11 g · min(-1), respectively). Performance times were 2.2% and 5.0% faster with MD+F compared with MD+F+P and MD, respectively; however, they were not statistically significant. Ingestion of an MD-fructose-protein commercial sports beverage significantly reduced peak and mean CHO(EXO) rates compared with MD+F, but did not significantly influence CHOTOT. The addition of protein to an MD+F beverage did not enhance performance times.
authors.affiliation: School of Life Sciences, Division of Sport, Health, and Exercise, University of Hertfordshire, College Lane, Hatfield, Hertfordshire, UK. mike.d.tarpey@gmail.com
authors.forename: Michael D
authors.initials: MD
authors.lastname: Tarpey
authors.forename: Justin D
authors.initials: JD
authors.lastname: Roberts
authors.forename: Lindsy S
authors.initials: LS
authors.lastname: Kass
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Tarpey
authors.forename: Michael G
authors.initials: MG
authors.lastname: Roberts
mesh_terms: D001628:Beverages; D001786:Blood Glucose / Q000378:metabolism; D004040:Dietary Carbohydrates / Q000378:metabolism; D015444:Exercise; D005632:Fructose; D006801:Humans
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D005632:Fructose