The Repeatability of the Effect of Caffeine Supplementation on Submaximal Physiological Responses and Cycling Time Trial Performance

Recently, Grgic (2018) discussed the concept of responders and non-responders to caffeine supplementation highlighting the importance of the repeatability of results. However, the number of studies that have investigated this idea by repeating the same time-trial performance test multiple times with the same caffeine dose is sparse (Astorino et al., 2012; Del Coso et al., 2019). Furthermore, studies have shown that differences in the CYP1A2 genotype may account for some of the variation in time-trial performance (Guest et al., 2018). Thus, the current study aims to identify whether the effects of moderate caffeine supplementation (5 mg/kg) on time-trial performance are repeatable to aid the identification of responders and non-responders. Additionally, the study aims to determine if the CYP1A2 genotype may explain any of the variability in time-trial performance in trained male cyclists.

Not Yet Recruiting

Trial opening soon.

Get Notified

Key information

Conditions

Caffeine

Age range

18 year–35 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

To be considered for inclusion in the study, participants must be regular cyclists, between 18 and 35 years of age, capable of completing a 20 km cycling time trial at a minimum speed of 30 km/h (arbitrary inclusion criteria to ensure a sufficient standard of athlete).

Exclusion criteria

Treatment and study plan

Caffeine

Dietary Supplement

5 mg/kg of caffeine in pill form

Placebo

Dietary Supplement

5 mg/kg dose of maltodextrin in pill form

Primary outcomes

Blood lactate concentration

Time frame: From baseline to completion, up to 31 days

Description: Change from baseline in blood lactate concentration measured at rest and at six different exercise intensities (55, 60, 65, 70, 75, and 80% percent of maximal oxygen uptake) on an electromagnetically-braked cycle ergometer
Heart rate

Time frame: From baseline to completion, up to 31 days

Change from baseline in heart rate measured at rest and at seven different exercise intensities (55, 60, 65, 70, 75, and 80% percent of maximal oxygen uptake) on an electromagnetically-braked cycle ergometer.
Oxygen uptake

Time frame: From baseline to completion, up to 31 days

Change from baseline in oxygen uptake measured at rest and at seven different exercise intensities (55, 60, 65, 70, 75, and 80% percent of maximal oxygen uptake) on an electromagnetically-braked cycle ergometer
Perceived exertion

Time frame: From baseline to completion, up to 31 days

Change from baseline in rating of perceived exertion measured (using the 6-20 Borg scale) at seven different exercise intensities (55, 60, 65, 70, 75, and 80% percent of maximal oxygen uptake) on an electromagnetically-braked cycle ergometer
Time trial completion time

Time frame: From baseline to completion, up to 31 days

Change from baseline in time to complete a time trial at a target amount of work on an electromagnetically-braked cycle ergometer calculated from the power output at maximal oxygen uptake and designed to last approximately 25 minutes.

Sponsors and collaborators

Lead sponsor

St. Mary's University, Twickenham

Other

Registry information

Important dates

Study start: 2025
Primary completion: 2025
Study completion: 2025
First posted: Apr 20, 2025
Registry last updated: Apr 20, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Published trials that share one or more normalized conditions with this study.

Not Yet Recruiting