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This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Date of Award

Spring 2010

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Department of Kinesiology

Advisor(s)

Nicholas D. Luden

Michael J. Saunders

Christopher Joseph Womack

Abstract

Purpose: The purpose of this study was to determine the independent and combined effects of carbohydrate and caffeine ingestion on performance and physiological parameters during high-intensity aerobic cycling (~60 minutes). Methods: Ten cyclists (28 ± 3 yr, 73.2 ± 1.9 kg) performed 20 minutes of steady-state cycling (60% Wmax) followed by a simulated 20-km time trial (TT) under the following four treatment conditions: placebo (PLA), carbohydrate (CHO), caffeine (CAF), and a combination of CHO and CAF (CHO-CAF). One hour prior to exercise subjects ingested a placebo/caffeine capsule. Beverages (250 ml) were consumed immediately prior to the 20-min steady-state, immediately prior to the 20-km TT, and at the 20-min mark during the time trial. Subjects completed the treatment trials in a semi-randomized, double-blind, placebo fashion and trials were separated by ≥ 5 days. Results: CHO-CAF improved 20-km TT performance by 3.4% (93 sec) compared to PLA (p ≤ 0.05), whereas no differences were detected among CHO, CAF, and PLA. Similarly, CHO-CAF improved mean power output by 5% during the 20-km TT compared to the PLA trial. RER was elevated under all treatment conditions compared to PLA. Further, blood glucose was elevated in CHO-CAF compared to PLA post steady-state and post TT. Treatment conditions did not differentially impact VE, VO2, pre-exercise MVC, post-exercise MVC, RPE, and blood lactate. Conclusions: CAF and CHO improve 20-km time trial performance when taken together but not when taken independently. This appears to be possibly facilitated by peripheral (MVC) and metabolic modifications (RER + blood glucose). Regardless of the mechanism, these data suggest that cyclists should ingest CHO and CAF together to improve high-intensity time trial performance, while in the fed state.

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