A whey-supplemented, high-protein diet versus a high-carbohydrate diet: effects on endurance cycling performance

Int J Sport Nutr Exerc Metab. 2006 Feb;16(1):65-77. doi: 10.1123/ijsnem.16.1.65.

Abstract

This study compared a training diet recommended for endurance athletes (H-CHO) with an isoenergetic high protein (whey supplemented), moderate carbohydrate (H-Pro) diet on endurance cycling performance. Over two separate 7-d periods subjects (n = 7) ingested either H-CHO (7.9 +/- 1.9 g x kg(-1) x d(-1) carbohydrate; 1.2 +/- 0.3 g x kg(-1) x d(-1) fat; 1.3 +/- 0.4 g x kg(-1) x d(-1) protein) or H-Pro (4.9 +/- 1.8 g x kg(-1) x d(-1); 1.3 +/- 0.3 g x kg(-1) x d(-1); 3.3 +/- 0.4 g x kg(-1) x d(-1)) diet in a randomized, balanced order. On day 8 subjects cycled (self-paced) for a body weight dependent (60 kJ/bm) amount of work. No differences occurred between energy intake (P = 0.422) or fat intake (P = 0.390) during the two dietary conditions. Performance was significantly (P = 0.010) impaired following H-Pro (153 +/- 36) compared with H-CHO (127 +/- 34 min). No differences between treatments were observed for physiological measures taken during the performance trials. These results indicate an ergolytic effect of a 7-d high protein diet on self-paced endurance cycling performance.

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Bicycling / physiology*
  • Blood Glucose / analysis
  • Diet*
  • Dietary Carbohydrates / administration & dosage*
  • Dietary Carbohydrates / adverse effects
  • Dietary Proteins / administration & dosage*
  • Dietary Proteins / adverse effects
  • Dietary Supplements*
  • Energy Intake / physiology
  • Energy Metabolism / physiology
  • Exercise Test / methods
  • Humans
  • Milk Proteins / administration & dosage*
  • Milk Proteins / adverse effects
  • Physical Endurance / drug effects*
  • Physical Endurance / physiology
  • Respiratory Function Tests / methods
  • Time Factors
  • Whey Proteins

Substances

  • Blood Glucose
  • Dietary Carbohydrates
  • Dietary Proteins
  • Milk Proteins
  • Whey Proteins