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

Preferred Name

Annette Lemanski

Date of Award

Spring 2017

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Department of Kinesiology

Advisor(s)

Nicholas D. Luden

Michael J. Saunders

Christopher Joseph Womack

David L. Wenos

Abstract

PURPOSE: There is evidence that female sex hormones impact caffeine metabolism, with decreased CYP1A2 activity and diminished caffeine clearance in women with higher estrogen levels. Therefore, the objectives of this project were to determine the effects of oral contraceptives and menstrual cycle on the benefits of caffeine supplementation for cycling performance. METHODS: Sixteen recreationally trained female cyclists, oral contraceptive steroid (OCS) users (n=8, age = 21.4 ± 1.4 years, height = 168.4 ± 3.6 cm, weight = 63.6 ± 7.2kg, VO2max = 48.0 ± 4.0 ml/kg/min), and non-users (n=8, age = 20.9 ± 2.1 years, height = 161.0 ± 7.7 cm, weight = 59.5 ± 9.2 kg, VO2max = 50.9 ± 7.8 ml/kg/min), completed four separate computer-simulated 3-km cycling time trials (TT). Subjects ingested either 6mg/kg of caffeine or a placebo capsule one hour prior to each trial. Magnitude based inferences were used to evaluate treatment differences. RESULTS: Caffeine enhanced 3-km TT performance (compared to placebo) in early and late phases of the menstrual cycle for OCS users ‘possibly’ and ‘very likely’ by 1.6 ± 2.1%, 2.7 ± 1.4% and non-users ‘likely’ by 2.6 ± 2.3%, 2.1 ± 2.2% respectively. All other comparisons for OCS users and non-users were ‘unclear’. CONCLUSIONS: Caffeine supplementation improved 3-km TT finishing time and average power output in follicular and luteal phases of the menstrual cycle, with unclear differences between the phases for both OCS users and non-users. This indicates that menstrual status is not a significant source of variability on the ergogenic effect of caffeine supplementation on cycling performance.

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