The effect of a low carbohydrate beverage with added protein on cycling endurance performance in trained athletes

J Strength Cond Res. 2010 Oct;24(10):2577-86. doi: 10.1519/JSC.0b013e3181ecccca.

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.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Athletes*
  • Athletic Performance*
  • Beverages*
  • Bicycling*
  • Dietary Carbohydrates / administration & dosage*
  • Dietary Proteins / administration & dosage
  • Dietary Supplements
  • Female
  • Fructose / administration & dosage
  • Glucose / administration & dosage
  • Humans
  • Male
  • Oxygen Consumption / drug effects
  • Physical Endurance / drug effects*
  • Polysaccharides / administration & dosage

Substances

  • Dietary Carbohydrates
  • Dietary Proteins
  • Polysaccharides
  • Fructose
  • maltodextrin
  • Glucose