title: Adding polylactate to a glucose polymer solution does not improve endurance.
abstract: Polylactate (PL), a semi-soluble amino acid/lactate salt, is a newly developed carbohydrate supplement purported to increase endurance. Our purpose was to determine if the addition of PL to a glucose polymer solution (GP) extends exercise time relative to a pure GP solution. In a double blind and random crossover design, 5 subjects exercised twice to exhaustion at 70% of VO2max. During the trials, they consumed GP or a GP/PL mixture at the rate of 0.3 g carbohydrate per kg of body wt in a 7% solution every 20 min until exhaustion. The GP/PL mixture contained 6.25 g GP to 0.75 g PL per 100 ml of water. Mixture composition was critical because PL, as supplied by the manufacturer and under our experimental conditions, produced severe gastro-intestinal efflux in concentrations > or = 2.5%; PL was tolerable in concentrations < or = 0.75%. At 20 min intervals, we measured VO2, respiratory exchange ratio, heart rate, and perceived exertion. At 30 min intervals, we measured serum glucose, insulin, free fatty acids, and glycerol as well as whole blood lactate and pH. We found that the addition of PL to a GP solution had no measurable physiological or performance effects.
authors.affiliation: Department of Zoology, University of Tennessee, Knoxville 37996.
authors.forename: T
authors.initials: T
authors.lastname: Swensen
authors.forename: G
authors.initials: G
authors.lastname: Crater
authors.forename: D R
authors.initials: DR
authors.lastname: Bassett
authors.forename: E T
authors.initials: ET
authors.lastname: Howley
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D004064:Digestive System / Q000187:drug effects; D004311:Double-Blind Method; D005080:Exercise Test; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology*; D005990:Glycerol / Q000097:blood; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007328:Insulin / Q000097:blood; D007773:Lactates / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000494:pharmacology*; D019344:Lactic Acid; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010465:Perception; D010807:Physical Endurance / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology; D010865:Pilot Projects; D011091:Polyesters; D011108:Polymers / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D012119:Respiration / Q000502:physiology; D012996:Solutions; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D007773:Lactates; D011091:Polyesters; D011108:Polymers; D012996:Solutions; D019344:Lactic Acid; C033616:poly(lactide); D005947:Glucose; D005990:Glycerol