title: The effect of a low carbohydrate beverage with added protein on cycling endurance performance in trained athletes.
abstract: Ingesting carbohydrate plus protein during prolonged variable intensity exercise has demonstrated improved aerobic endurance performance beyond that of a carbohydrate supplement alone. The purpose of the present study was to determine if a supplement containing a mixture of different carbohydrates (glucose, maltodextrin, and fructose) and a moderate amount of protein given during endurance exercise would increase time to exhaustion (TTE), despite containing 50% less total carbohydrate than a carbohydrate-only supplement. We also sought post priori to determine if there was a difference in effect based on percentage of ventilatory threshold (VT) at which the subjects cycled to exhaustion. Fifteen trained male and female cyclists exercised on 2 separate occasions at intensities alternating between 45 and 70% VO2max for 3 hours, after which the workload increased to ∼74-85% VO2max until exhaustion. Supplements (275 mL) were provided every 20 minutes during exercise, and these consisted of a 3% carbohydrate/1.2% protein supplement (MCP) and a 6% carbohydrate supplement (CHO). For the combined group (n = 15), TTE in MCP did not differ from CHO (31.06 ± 5.76 vs. 26.03 ± 4.27 minutes, respectively, p = 0.064). However, for subjects cycling at or below VT (n = 8), TTE in MCP was significantly greater than for CHO (45.64 ± 7.38 vs. 35.47 ± 5.94 minutes, respectively, p = 0.006). There were no significant differences in TTE for the above VT group (n = 7). Our results suggest that, compared to a traditional 6% CHO supplement, a mixture of carbohydrates plus a moderate amount of protein can improve aerobic endurance at exercise intensities near the VT, despite containing lower total carbohydrate and caloric content.
authors: Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, Texas, USA.
authors: Lisa
authors: L
authors: Ferguson-Stegall
authors: Erin L
authors: EL
authors: McCleave
authors: Zhenping
authors: Z
authors: Ding
authors: Lynne M
authors: LM
authors: Kammer
authors: Bei
authors: B
authors: Wang
authors: Phillip G
authors: PG
authors: Doerner
authors: Yang
authors: Y
authors: Liu
authors: John L
authors: JL
authors: Ivy
mesh_terms: D000328:Adult; D056352:Athletes; D054874:Athletic Performance; D001628:Beverages; D001642:Bicycling; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004044:Dietary Proteins / Q000008:administration & dosage; D019587:Dietary Supplements; D005260:Female; D005632:Fructose / Q000008:administration & dosage; D005947:Glucose / Q000008:administration & dosage; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects; D010807:Physical Endurance / Q000187:drug effects*; D011134:Polysaccharides / Q000008:administration & dosage
chemical_list: D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D011134:Polysaccharides; D005632:Fructose; C008315:maltodextrin; D005947:Glucose