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Kateri M. Roessler 2004

Kateri M. Roessler: Natural Science major

Effects of Exercise and Hydration Status on Urinary Caffeine Concentrations

Current work was primarily performed on male subjects in controlled laboratory settings. Recently world class athletes, including runners Letitia Vreisde and Inger Miller, had gold medals taken away after drug tests showed urinary caffeine levels exceeding the legal limit.

This study focused on healthy female college cross country runners and examined hydration status in addition to exercise. Urinary caffeine concentrations were assessed after ingesting 5 mg caffeine per kilogram body weight both with exercise (and subsequent mild hydration change) and without exercise.

In both trials subjects ingested 1 L of caffeinated sports drink. Drinks were prepared so each subject received 5 milligrams caffeine per kilogram body weight. In the exercise trial subjects ran outside under normal training conditions for 60 minutes, one hour after ingestion. Urinary caffeine concentrations were assessed using Liquid Chromatography Mass Spectroscopy.

Research Advisor: Amy Olson


Caffeine is an effective ergogenic (performance enhancing) aid at doses of 3-5 milligrams caffeine per kilogram body weight (roughly the amount in 2-3 cups of coffee). However, the NCAA imposes a legal limit for urinary caffeine concentration at 15 micrograms per milliliter. The amount of oral caffeine that results in exceeding this limit and the effects of exercise and hydration on caffeine excretion is unclear.