title: A low carbohydrate-protein supplement improves endurance performance in female athletes.
abstract: The purpose of this study was to investigate if a low mixed carbohydrate (CHO) plus moderate protein (PRO) supplement, provided during endurance exercise, would improve time to exhaustion (TTE) in comparison to a traditional 6% CHO supplement. Fourteen (n = 14) trained female cyclists and triathletes cycled on 2 separate occasions for 3 hours at intensities varying between 45 and 70% VO2max, followed by a ride to exhaustion at an intensity approximating the individual's ventilatory threshold average 75.06% VO2max. Supplements (275 mL) were provided every 20 minutes during exercise and were composed of a CHO mixture (1% each of dextrose, fructose, and maltodextrin) + 1.2% PRO (CHO + PRO) or 6% dextrose only (CHO). The TTE was significantly greater with CHO + PRO in comparison to with CHO (49.94 ± 7.01 vs. 42.36 ± 6.21 minutes, respectively, p < 0.05). Blood glucose was significantly lower during the CHO + PRO trial (4.07 ± 0.12 mmol · L(-1)) compared to during the CHO trial (4.47 ± 0.12 mmol · L(-1)), with treatment × time interactions occurring from 118 minutes of exercise until exhaustion (p < 0.05). Results from the present study suggest that the addition of a moderate amount of PRO to a low mixed CHO supplement improves endurance performance in women above that of a traditional 6% CHO supplement. Improvement in performance occurred despite CHO + PRO containing a lower CHO and caloric content. It is likely that the greater performance seen with CHO + PRO was a result of the CHO-PRO combination and the use of a mixture of CHO sources.
authors.affiliation: Exercise Physiology and Metabolism Laboratory, Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, Texas, USA.
authors.forename: Erin L
authors.initials: EL
authors.lastname: McCleave
authors.forename: Lisa
authors.initials: L
authors.lastname: Ferguson-Stegall
authors.forename: Zhenping
authors.initials: Z
authors.lastname: Ding
authors.forename: Phillip G
authors.initials: PG
authors.lastname: Doerner
authors.forename: Bei
authors.initials: B
authors.lastname: Wang
authors.forename: Lynne M
authors.initials: LM
authors.lastname: Kammer
authors.forename: John L
authors.initials: JL
authors.lastname: Ivy
mesh_terms: D000328:Adult; D056352:Athletes; D054874:Athletic Performance; D001786:Blood Glucose / Q000187:drug effects / Q000502:physiology; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004044:Dietary Proteins / Q000008:administration & dosage*; D019587:Dietary Supplements; D005080:Exercise Test; D005221:Fatigue / Q000503:physiopathology; D005260:Female; D006801:Humans; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D010807:Physical Endurance / Q000187:drug effects
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004044:Dietary Proteins