Added Protein Maintains Efficacy of a Low-Carbohydrate Sports Drink

• Published in: Journal of strength and conditioning research 2010-01, Vol.24 (1), p.48-59
• Main Authors: Martínez-Lagunas, Vanessa, Ding, Zhenping, Bernard, Jeffrey R, Wang, Bei, Ivy, John L
• Format: Article
• Language: English
• Subjects: Adult; Athletes; Beverages; Bicycling - physiology; Blood Glucose - analysis; Data collection; Diet; Dietary Carbohydrates - administration & dosage; Dietary Carbohydrates - pharmacology; Dietary Proteins - administration & dosage; Dietary Proteins - pharmacology; Exercise - physiology; Fatty Acids, Nonesterified - blood; Female; Heart Rate - drug effects; Humans; Insulin - blood; Male; Muscle Fatigue - drug effects; Muscle Fatigue - physiology; Oxygen Consumption - drug effects; Physical Exertion - drug effects; Physical Exertion - physiology; Physical fitness; Respiration - drug effects; Studies; Young Adult
• ISSN: 1064-8011; 1533-4287
• DOI: 10.1519/JSC.0b013e3181c32e20

Martínez-Lagunas, V, Ding, Z, Bernard, JR, Wang, B, and Ivy, JL. Added protein maintains efficacy of a low-carbohydrate sports drink. J Strength Cond Res 24(1)48-59, 2010-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% o2max for 2.5 hours and then at 80% o2max 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% o2max 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.