The effect of polylactate on endurance performance

Author

Thomas C. Swensen

Date of Award

12-1992

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Life Sciences

Major Professor

Roland Bagby

Committee Members

Edward T. Howley, David R. Bassett. James, M. Liles

Abstract

The purpose of this work was to examine the effect of polylactate (PL) on endurance performance. PL is a semi-soluble amino acid/lactate salt, and it is purported to enhance performance when ingested during endurance exercise. We decided to test PL's effect on endurance performance as a component of a glucose polymer (GP) solution, the ergogenic standard, after we found from a series of pilot studies that PL, as provided by the manufacturer and under our experimental conditions, was toxic in solution concentrations ≥ 2.5% but tolerable in concentrations ≤.75%. The test solution contained .75 g PL to 6.25 g GP per 100 ml of water - a mixture that has 50% more PL per serving than the commercially available PL product as mixed according to directions. In a double blind and random crossover design, 5 subjects performed 2 exercise trials to exhaustion at 70% of VO_{2 max}. During the trials, the subjects consumed either glucose polymers or a PL/GP mixture at the rate of .3 g carbohydrate per kg body wt in a 7% solution every 20 min until exhaustion. At 20 min intervals, VO₂, respiratory exchange ratio, heart rate, and perceived exertion were measured. At 30 min intervals, 10 ml of blood were drawn from an indwelling venous catheter for subsequent determination of serum glucose, insulin, free fatty acids, and glycerol as well as whole blood lactate and pH. We found that mean time to exhaustion was similar for both trials (214.6±.17 min in the GP trial and 214.4 ±.22 min in the PL trial); all the other variables were also similar between the trials. We concluded that PL had no effect on endurance performance beyond that produced solely by a GP drink and, given PL's toxicity in concentrations ≥ 2.5% under our experimental conditions, we question its use as a component of a sport drink.

Recommended Citation

Swensen, Thomas C., "The effect of polylactate on endurance performance. " PhD diss., University of Tennessee, 1992.
https://trace.tennessee.edu/utk_graddiss/11006