Assessment of the performance-enhancing effect of caffeine in the menstrual cycle phases in women athletes of cycling

Assessment of the ergogenic effect of caffeine consumption in different phases of the menstrual cycle in cycling athletes: a randomized crossover clinical trial

Status

Recruiting

Phases

Unknown

Study type

Interventional

Source

REBEC

Registry ID

RBR-76js9yv

Enrollment

Registered

2026-05-22

Start date

2025-05-01

Completion date

Unknown

Last updated

2026-06-01

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Follicular phase

Interventions

This is a randomized, placebo-controlled, crossover, double-blind clinical trial. A total of 22 female cycling or triathlon athletes will be randomly allocated using the Latin Square design. Both the

Eligibility

Sex/Gender

Female

Age

18 Years to 40 Years

Inclusion criteria

Inclusion criteria: Women; age between 18 and 40 years; stable body weight over the last three months; regular consumers of coffee/caffeine; at least 1 year of experience of regular training, maintaining a total of more than 100 km of cycling training per week; having a regular menstrual cycle with a variance of no more than 3 days; without using contraceptives in the last 3 months

Exclusion criteria

Exclusion criteria: Any type of injury in the last 6 months; smokers; with alcohol consumption of more than 7 units/week; who have a previous history of lung or cardiovascular diseases; allergy/intolerance to caffeine; who have any type of menstrual dysfunction (polycystic ovary syndrome, amenorrhea, oligomenorrhea, dysmenorrhea or premenstrual dysphoric syndrome); are pregnant and using hormonal contraceptives

Design outcomes

Primary

Measure	Time frame
It is expected to find a lesser time to complete a 20-km cycling time trial with the caffeine intake in comparison to the placebo, measured on the clock	—

Secondary

Measure	Time frame
It is expected to find a higher mean power in the 20-km cycling time trial with the caffeine intake in comparison to the placebo, evaluated by the output of the bicycle roller Wahoo;It is expected to find a higher heart rate in the 20-km cycling time trial with the caffeine intake in comparison to the placebo, evaluated by heart rate monitors, model Polar H10;It is expected to find a lesser perceived exertion in a 20-km cycling time trial with the caffeine intake in comparison to the placebo, evaluated by 20 points Borg Scale;It is expected to find a higher blood lactate in the 20-km cycling time trial with the caffeine intake in comparison to the placebo, verified by finger prick lactometer	—

Measure

Time frame

It is expected to find a higher mean power in the 20-km cycling time trial with the caffeine intake in comparison to the placebo, evaluated by the output of the bicycle roller Wahoo;It is expected to find a higher heart rate in the 20-km cycling time trial with the caffeine intake in comparison to the placebo, evaluated by heart rate monitors, model Polar H10;It is expected to find a lesser perceived exertion in a 20-km cycling time trial with the caffeine intake in comparison to the placebo, evaluated by 20 points Borg Scale;It is expected to find a higher blood lactate in the 20-km cycling time trial with the caffeine intake in comparison to the placebo, verified by finger prick lactometer

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Countries

Contacts

Public ContactGloria Bittencourt

Universidade de Brasília

gloria.bittencourtsr@gmail.com+55(61)99689-0209

Outcome results

None listed

Source: REBEC (via WHO ICTRP) · Data processed: Jun 11, 2026