title: The effect of galactose supplementation on endurance cycling performance.
abstract: OBJECTIVE
  This study tested the hypothesis that supplementation with galactose before and during endurance exercise would spare carbohydrate (CHO), optimize fat utilization and improve performance compared with a typical sports drink formulation.
  
  
  METHODS
  Nine well-trained cyclists undertook three trials, each consisting of 120 min at 65 VO(2max) followed immediately by a set work, self-paced time trial (TT). Three treatments, allocated as a randomized balanced design, consisted of the following: (a) 8% (w/w) solution of galactose (Gal); (b) 8% solution of 50% galactose/50% glucose (Gluc/Gal); and (c) 8% solution of 80% glucose/20% fructose (Gluc/Fru). These were consumed as 0.67 g CHO per kg body wt 45-min pre-exercise; 1.0 g CHO per kg body wt per h for the first 120 min of exercise; 0.33 g CHO per kg body wt during the TT. Blood samples were collected before and during exercise; respiratory gas samples were collected only during fixed workload exercise.
  
  
  RESULTS
  Mean TT power output was significantly less in Gal compared with Gluc/Gal (P=0.030). Blood glucose and insulin concentrations were lower, and free fatty acids higher in Gal compared with Gluc/Gal and Gluc/Fru. Respiratory exchange ratio was not significantly different between trials.
  
  
  CONCLUSIONS
  Ingestion of an 8% galactose-only solution (12.5 ml per kg body wt per h) is detrimental to endurance performance compared with equivalent volumes of iso-osmotic solutions containing 50% galactose/50% glucose or 80% glucose/20% fructose. This may reflect the inability of the liver to convert galactose into glucose at a rate required to support strenuous exercise intensity.
authors.affiliation: Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand. S.Stannard@massey.ac.nz
authors.forename: S R
authors.initials: SR
authors.lastname: Stannard
authors.forename: E J
authors.initials: EJ
authors.lastname: Hawke
authors.forename: N
authors.initials: N
authors.lastname: Schnell
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D001628:Beverages; D001642:Bicycling / Q000502:physiology*; D001786:Blood Glucose / Q000378:metabolism; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005632:Fructose / Q000494:pharmacology; D005690:Galactose / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology; D006601:Hexoses / Q000494:pharmacology*; D006801:Humans; D007328:Insulin / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000502:physiology
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D005230:Fatty Acids, Nonesterified; D006601:Hexoses; D007328:Insulin; D005632:Fructose; D019344:Lactic Acid; D005947:Glucose; D005690:Galactose