title: Improved gross efficiency during long duration submaximal cycling following a short-term high carbohydrate diet.
abstract: To assess the effect of dietary manipulation on gross efficiency (GE), 15 trained male cyclists completed 3×2 h tests at submaximal exercise intensity (60% Maximal Minute Power). Using a randomized, crossover design participants consumed an isoenergetic diet (~4 000 kcal.day-1) in the 3 days preceding each test, that was either high in carbohydrate (HighCHO, [70% of the total energy derived from carbohydrate, 20% fat, 10% protein]), low in carbohydrate (LowCHO, [70% fat, 20% carbohydrate, 10% protein]) or contained a moderate amount of carbohydrate (ModCHO, [45% carbohydrate, 45% fat, 10% protein]). GE along with blood lactate and glucose were assessed every 30 min, and heart rate was measured at 5 s intervals throughout. Mean GE was significantly greater following the HighCHO than the ModCHO diet (HighCHO=20.4%±0.1%, ModCHO=19.6±0.2%; P<0.001). Additionally, HighCHO GE was significantly greater after 25 min (P=0.015) and 85 min (P=0.021) than in the LowCHO condition. Heart rate responses in the HighCHO condition were significantly lower than during the LowCHO tests (P=0.005). Diet had no effect on blood glucose or lactate (P>0.05). This study suggests that before the measurement of gross efficiency, participants' diet should be controlled and monitored to ensure the validity of the results obtained.
authors.affiliation: Sports Science, Tourism & Leisure, Canterbury Christ Church University, Canterbury, United Kingdom.
authors.forename: M
authors.initials: M
authors.lastname: Cole
authors.affiliation: Sports Science, Tourism & Leisure, Canterbury Christ Church University, Canterbury, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Coleman
authors.affiliation: Centre for Sport Studies, University of Kent, Chatham, United Kingdom.
authors.forename: J
authors.initials: J
authors.lastname: Hopker
authors.affiliation: Sports Science, Tourism & Leisure, Canterbury Christ Church University, Canterbury, United Kingdom.
authors.forename: J
authors.initials: J
authors.lastname: Wiles
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology*; D001786:Blood Glucose / Q000378:metabolism; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D004526:Efficiency / Q000502:physiology*; D004734:Energy Metabolism; D006339:Heart Rate; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010807:Physical Endurance / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D019344:Lactic Acid