title: Added protein maintains efficacy of a low-carbohydrate sports drink.
abstract: The purpose of the present study was to investigate the aerobic capacity characteristics of an isocaloric carbohydrate (CHO) plus protein (PRO) drink and a low-calorie CHO plus PRO drink against a traditional 6% CHO sports beverage. Twelve male and female trained cyclists exercised on 4 separate occasions at intensities that varied between 55 and 75% V(O2)max for 2.5 hours and then at 80% V(O2)max until fatigued. Supplements (255.4 +/- 9.1 mL) were provided every 20 minutes and consisted of a 4.5% carbohydrate plus 1.15% protein complex (CHO/PRO H), a 3% carbohydrate plus 0.75% protein complex (CHO/PRO L), a 6% carbohydrate supplement (CHO), or a placebo (PLA). Time to fatigue at 80% V(O2)max was significantly longer (p < 0.05) during the CHO (26.9 +/- 6.1 minutes, mean +/- SE), the CHO/PRO H (30.5 +/- 5.9 minutes), and the CHO/PRO L (28.9 +/- 6.5 minutes) trials compared with the PLA trial (14.7 +/- 3.4 minutes), with no significant differences among the CHO, CHO/PRO H, and CHO/PRO L treatments. In general, blood glucose, plasma insulin, and carbohydrate oxidation were elevated above PLA during the CHO, CHO/PRO H, and CHO/PRO L trials, whereas plasma free fatty acids, rating of perceived exertion, and fat oxidation values were lower during the CHO, CHO/PRO H, and CHO/PRO L trials compared with the PLA trial. Only minor differences in blood parameters occurred among the CHO, CHO/PRO H, and CHO/PRO L treatments. In summary, partially substituting PRO for CHO in a sports drink did not enhance aerobic capacity, but substitution was able to occur without loss of efficacy. Thus, adding PRO to a low-calorie CHO sports drink may be an effective strategy to enhance aerobic capacity while limiting carbohydrate and caloric consumption.
authors.affiliation: Department of Kinesiology and Health Education, The University of Texas at Austin Exercise Physiology and Metabolism Laboratory, Austin, Texas, USA.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Martínez-Lagunas
authors.forename: Zhenping
authors.initials: Z
authors.lastname: Ding
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Bernard
authors.forename: Bei
authors.initials: B
authors.lastname: Wang
authors.forename: John L
authors.initials: JL
authors.lastname: Ivy
mesh_terms: D000328:Adult; D056352:Athletes; D001628:Beverages; D001642:Bicycling / Q000502:physiology; D001786:Blood Glucose / Q000032:analysis; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000494:pharmacology*; D004044:Dietary Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D015444:Exercise / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D018763:Muscle Fatigue / Q000187:drug effects / Q000502:physiology; D010101:Oxygen Consumption / Q000187:drug effects; D005082:Physical Exertion / Q000187:drug effects / Q000502:physiology; D012119:Respiration / Q000187:drug effects; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D005230:Fatty Acids, Nonesterified; D007328:Insulin