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.

The Effects of Two Different Doses of Calcium Lactate on Blood pH, Bicarbonate, and Repeated High-Intensity Exercise Performance

“…In fact, the oral ingestion of lactate (in the form of polylactate, sodium lactate or calcium lactate) has been studied since 1991, when Fahey and colleagues concluded that lactate may be used as an energy substrate to help maintain blood glucose during endurance exercise. Although one study has shown a remarkable 25% improvement in endurance exercise performance following lactate supplementation (Azevedo et al, 2007), most studies have failed to show any benefit (Bryner et al, 1998;Northgraves et al, 2013;Preveler & Palmer, 2012;Swensen et al, 1994).…”

Effects of Ingestion of Bicarbonate, Citrate, Lactate, and Chloride on Sprint Running

“…A number of researchers have investigated the influence of polylactate ingestion on endurance performance (2,3,19,22), since Brooks (1) found that lactate can serve as an energy source for exercising muscles. In the study of Fahey et al (3), the ingestion of 80% polylactate and 20% sodium lactate as a 7% solution in water increased blood pH and bicarbonate compared to ingestion of a glucose polymer drink.…”

Lactate, Fructose and Glucose Oxidation Profiles in Sports Drinks and the Effect on Exercise Performance

“…Prior to the present research, two other studies sought to determine the efficacy of lactate as a sports drink component [5], [16]. Neither study utilized tracers to quantify metabolite fractional oxidation rates as was done in the present investigation.…”

“…To date, however, the efficacy of adding lactate to these drinks has been sparsely assessed [5], [15], [16]. Lactate was once considered a metabolic waste but is now recognized as an important energy substrate in the body.…”