title: Does a pre-exercise carbohydrate feeding improve a 20-km cross-country ski performance?
abstract: OBJECTIVE
  Carbohydrates are known to improve exercise performance, but their effects on actual competitions are not studied in detail. Aim of the present work was to evaluate the effects of maltodextrins ingestion on a simulated cross-country ski competition.
  
  
  METHODS
  Ten athletes (15-24 years) repeated twice, in random order, a 20-km time-trial; 45 min prior to the start, they consumed 508+/-64 mL of a beverage containing either 0.7 g x kg(-1) body mass of maltodextrins or carbohydrate free placebo.
  
  
  RESULTS
  Blood glucose, lactate and rate of perceived exertion (RPE) were measured periodically; heart rate was acquired continuously. Maltodextrins ingestion did not affect the increase in lactate and RPE at the end of the trial (5.2+/-3.7 mmol x L(-1) and 17.5+/-2.2), nor heart rate, which was constant throughout the exercises (177.1+/-4.3 bpm). The environmental conditions changed statistically in the second experimental session (-10.2+/-1.8 degrees C vs -0.8+/-0.5 degrees C for snow temperature, P<0.05), giving rise to shorter performance times of all the athletes (67.9+/-5.9 min vs 63.5+/-5.8 min, P<0.005). Within each session, the average performance time of the athletes receiving maltodextrins was shorter, even if not significantly. However, the difference in performance time of the group fed with the maltodextrins the 2nd day, was statistically higher (6.1+/-1.7 min vs 3.4+/-1.5 min, P<0.03). The effects of maltodextrins ingestion were disentangled mathematically, leading to an estimated gain in performance time of 2%.
  
  
  CONCLUSIONS
  In spite of the different environmental conditions during the 2 experimental sessions, the illustrated results suggest an improvement of total performance time following the maltodextrins feeding.
authors.affiliation: Department of Biomedical Sciences and Technologies, University of Udine, Udine, Italy. MFrancescato@mail.dstb.uniud.it
authors.forename: M P
authors.initials: MP
authors.lastname: Francescato
authors.forename: I
authors.initials: I
authors.lastname: Puntel
mesh_terms: D000293:Adolescent; D000328:Adult; D001628:Beverages; D001786:Blood Glucose / Q000032:analysis; D003080:Cold Temperature; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006813:Humidity; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008320:Maltose / Q000008:administration & dosage*; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology; D010919:Placebos; D011134:Polysaccharides / Q000008:administration & dosage*; D011597:Psychomotor Performance / Q000502:physiology*; D012865:Skiing / Q000502:physiology*; D012914:Snow; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D010919:Placebos; D011134:Polysaccharides; D019344:Lactic Acid; D008320:Maltose; C008315:maltodextrin