The Effect of ad libitum Ingestion of a Caffeinated Carbohydrate-Electrolyte Solution on Urinary Caffeine Concentration After 4 Hours of Endurance Exercise

Abstract

The purpose of the present study was to examine the effect of ad libitum ingestion of a carbohydrate-electrolyte solution (CES) with 150 mg × L^-1 caffeine (CAF) on urinary CAF concentration after 4 h of endurance exercise. Fifty-eight healthy and well-trained male subjects ingested ad libitum a 7 % CES with 150 mg × L^-1 CAF during 4 h cycling at 50 % of maximal work capacity. Total fluid consumption (mean ± SE) was 2799 ± 72 mL and CAF intake was 420 ± 11 mg (5.7 ± 0.2 mg × kg^-1 body weight). The post-exercise urinary CAF concentration (4.53 ± 0.25 µg × mL^-1) was below the doping level of the International Olympic Committee (12 µg × mL^-1) in all subjects (range 1.20 - 10.84 µg × mL^-1). A highly positive correlation was observed between CAF intake and post-exercise urinary CAF concentration (r = 0.68, p < 0.001). It is concluded that ad libitum ingestion of a CES with 150 mg × L^-1 CAF during 4 h cycling resulted in post-exercise urinary concentration below the doping level in all subjects.

Key words

Caffeine - carbohydrate-electrolyte solution - endurance - doping

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